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LTC2919 Precision Triple/Dual Input UV, OV and Negative Voltage Monitor FEATURES

DESCRIPTIO

Two Low Voltage Adjustable Inputs (0.5V) Accurate UVLO Provides a Third Monitor Input Open-Drain RST, OUT1 and OUT2 Outputs Pin Selectable Input Polarity Allows Negative, UV and OV Monitoring Guaranteed Threshold Accuracy: 1.5% 6.5V Shunt Regulator for High Voltage Operation Low 50A Quiescent Current Buffered 1V Reference for Negative Supply Offset Input Glitch Rejection Adjustable Reset Timeout Period Selectable Internal Timeout Saves Components Outputs Guaranteed Low With VCC = 0.5V Space Saving 10-Lead 3mm x 2mm DFN and MSOP Packages
The LTC(R)2919 is a triple/dual input monitor intended for a variety of system monitoring applications. Polarity selection and a buffered reference output allow the LTC2919 to monitor positive and negative supplies for undervoltage (UV) and overvoltage (OV) conditions. The two adjustable inputs have a nominal 0.5V threshold, featuring tight 1.5% threshold accuracy over the entire operating temperature range. Glitch filtering ensures outputs operate reliably without false triggering. An accurate threshold at the VCC pin provides a third input supply monitor for a 2.5V, 3.3V or 5V supply. Two independent output pins indicate the status of each adjustable input. A third common output provides a configurable reset timeout that may be set by an accurate internal 200ms timer, programmed with an external capacitor, or disabled for a fast response. A three-state input pin sets the input polarity of each adjustable input without requiring any external components. The LTC2919 provides a highly versatile, precise, spaceconscious, micropower solution for supply monitoring.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6949965, 7292076.
APPLICATIO S

Desktop and Notebook Computers Network Servers Core, I/O Monitor Automotive
TYPICAL APPLICATIO
3.3V UV/OV (Window) Monitor Application with 200ms Internal Timeout (3.3V Logic Out) SEL Pin Connection for Input Polarity Combinations
453k ADJ1 10.7k REF ADJ2 76.8k SEL GND
2919 TA01a
3.3V VCC LTC2919-2.5 OUT1 OUT2 RST TMR UV OV 10k 10k 10k FAULT 0.1F
POLARITY ADJ1 ADJ2 SEL PIN VCC OPEN GND
+ + -
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+ - -
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LTC2919 ABSOLUTE AXI U RATI GS
Terminal Voltages VCC (Note 3)............................................. -0.3V to 6V OUT1, OUT2, RST ................................. -0.3V to 7.5V ADJ1, ADJ2 .......................................... -0.3V to 7.5V TMR, SEL..................................-0.3V to (VCC + 0.3V) Terminal Currents ICC (Note 3)......................................................10mA IREF ....................................................................1mA
PIN CONFIGURATION
TOP VIEW SEL 1 VCC 2 OUT1 3 OUT2 4 RST 5 11 10 ADJ1 9 8 7 6 ADJ2 TMR REF GND SEL VCC OUT1 OUT2 RST 1 2 3 4 5 TOP VIEW 10 9 8 7 6 ADJ1 ADJ2 TMR REF GND
DDB PACKAGE 10-LEAD (3mm x 2mm) PLASTIC DFN TJMAX = 150C, JA = 76C/W EXPOSED PAD (PIN 11) MAY BE LEFT OPEN OR TIED TO GND
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2919CDDB-2.5#PBF LTC2919CDDB-2.5#TRPBF LDGT 10-Lead (3mm x 2mm) Plastic DFN 0C to 70C LTC2919IDDB-2.5#PBF LTC2919IDDB-2.5#TRPBF LDGT 10-Lead (3mm x 2mm) Plastic DFN -40C to 85C LTC2919HDDB-2.5#PBF LTC2919HDDB-2.5#TRPBF LDGT 10-Lead (3mm x 2mm) Plastic DFN -40C to 125C LTC2919CDDB-3.3#PBF LTC2919CDDB-3.3#TRPBF LDMW 10-Lead (3mm x 2mm) Plastic DFN 0C to 70C LTC2919IDDB-3.3#PBF LTC2919IDDB-3.3#TRPBF LDMW 10-Lead (3mm x 2mm) Plastic DFN -40C to 85C LTC2919HDDB-3.3#PBF LTC2919HDDB-3.3#TRPBF LDMW 10-Lead (3mm x 2mm) Plastic DFN -40C to 125C LTC2919CDDB-5#PBF LTC2919CDDB-5#TRPBF LDMX 10-Lead (3mm x 2mm) Plastic DFN 0C to 70C LTC2919IDDB-5#PBF LTC2919IDDB-5#TRPBF LDMX 10-Lead (3mm x 2mm) Plastic DFN -40C to 85C LTC2919HDDB-5#PBF LTC2919HDDB-5#TRPBF LDMX 10-Lead (3mm x 2mm) Plastic DFN -40C to 125C LTC2919CMS-2.5#PBF LTC2919CMS-2.5#TRPBF LTDGS 10-Lead Plastic MSOP 0C to 70C LTC2919IMS-2.5#PBF LTC2919IMS-2.5#TRPBF LTDGS 10-Lead Plastic MSOP -40C to 85C LTC2919HMS-2.5#PBF LTC2919HMS-2.5#TRPBF LTDGS 10-Lead Plastic MSOP -40C to 125C LTC2919CMS-3.3#PBF LTC2919CMS-3.3#TRPBF LTDMT 10-Lead Plastic MSOP 0C to 70C LTC2919IMS-3.3#PBF LTC2919IMS-3.3#TRPBF LTDMT 10-Lead Plastic MSOP -40C to 85C LTC2919HMS-3.3#PBF LTC2919HMS-3.3#TRPBF LTDMT 10-Lead Plastic MSOP -40C to 125C LTC2919CMS-5#PBF LTC2919CMS-5#TRPBF LTDMV 10-Lead Plastic MSOP 0C to 70C LTC2919IMS-5#PBF LTC2919IMS-5#TRPBF LTDMV 10-Lead Plastic MSOP -40C to 85C LTC2919HMS-5#PBF LTC2919HMS-5#TRPBF LTDMV 10-Lead Plastic MSOP -40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *Temperature grades are identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
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(Notes 1, 2)
Operating Temperature Range LTC2919C ................................................ 0C to 70C LTC2919I..............................................- 40C to 85C LTC2919H .......................................... -40C to 125C Maximum Junction Temperature........................... 150C Storage Temperature Range...................- 65C to 150C Lead Temperature (Soldering, 10 sec) MSOP-10 .......................................................... 300C
MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 150C, JA = 120C/W
LTC2919 ELECTRICAL CHARACTERISTICS
SYMBOL VCC(MIN) VCC(SHUNT) ICC VRT VRT IADJ VCC(UVLO) PARAMETER Operating Supply Voltage VCC Shunt Regulation Voltage VCC Input Current ADJ Input Threshold
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 2.5V (LTC2919-2.5), VCC = 3.3V (LTC2919-3.3), VCC = 5V (LTC2919-5), ADJ1 = ADJ2 = 0.55V, SEL = floating, unless otherwise noted. (Note 2)
CONDITIONS RST, OUT1, OUT2 in Correct State ICC = 1mA, IREF = 0 2.175V < VCC < 6V (C-Grade, I-Grade) 2.175V < VCC < 6V (H-Grade)

MIN 0.5 6.0
TYP 6.5 50 50
MAX 7.1 220 280 505.0 507.5 10.0 15 40 2.250 2.970 4.500 2.0 1.010 1.015 -2.9 2.9 27 280 VCC - 0.10 160 0.40 160 800 800 0.15 0.15 0.30 1 5 0.4 VCC
UNITS V V A A mV mV mV nA nA V V V % V V A A ms ms V mV V mV s s V V V A A V V V
495.0 492.5 1.5
500 500 3.5 0 0
ADJ Hysteresis (Note 4) ADJ Input Current VCC -10% UVLO Threshold
TMR = VCC VADJ = 0.55V (C-Grade, I-Grade) VADJ = 0.55V (H-Grade) LTC2919-2.5 LTC2919-3.3 LTC2919-5 TMR = VCC VCC > 2.175V, IREF = 1mA

2.175 2.871 4.350 0.3 0.990 0.985 -1.5 1.5 15 140 VCC - 0.40 40 0.10 40 50 50 0 0 0
2.213 2.921 4.425 0.7 1.000 1.000 -2.2 2.2 20 200 VCC - 0.20 100 0.20 100 150 150 0.01 0.01 0.10 0 0
VCC(UVLO) VREF ITMR(UP) ITMR(DOWN) tRST(EXT) tRST(INT) VTMR(DIS) VTMR(DIS) VTMR(INT) VTMR(INT) tPROP tUV VOL
UVLO Hysteresis (Note 4) Buffered Reference Voltage TMR Pull-Up Current TMR Pull-Down Current Reset Timeout Period, External Reset Timeout Period, Internal Timer Disable Voltage Timer Disable Hysteresis Timer Internal Mode Voltage Timer Internal Mode Hysteresis ADJx Comparator Propagation Delay to OUTX VCC Undervoltage Detect to RST Output Voltage Low
VTMR = 1V VTMR = 1V CTMR = 2.2nF VTMR = 0V VTMR Rising VTMR Falling VTMR Falling VTMR Rising ADJx Driven Beyond Threshold (VRTX) by 5mV VCC Less Than UVLO Threshold (VCC(UVLO)) by 1% VCC = 0.5V, I = 5A VCC = 1V, I = 100A VCC = 3V, I = 2500A Output = VCC (C-Grade, I-Grade) Output = VCC (H-Grade)

IOH
Output Voltage High Leakage
Three-State Input SEL VIL VIH VZ Low Level Input Voltage High Level Input Voltage Pin Voltage when Left in Open State ISEL = 0A

0 1.4 0.8 0.9
1.0
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LTC2919 ELECTRICAL CHARACTERISTICS
SYMBOL ISEL(Z) ISEL PARAMETER Allowable Leakage When Open SEL Input Current SEL = VCC or SEL = GND
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 2.5V (LTC2919-2.5), VCC = 3.3V (LTC2919-3.3), VCC = 5V (LTC2919-5), ADJ1 = ADJ2 = 0.55V, SEL = floating, unless otherwise noted. (Note 2)
CONDITIONS

MIN
TYP 17
MAX 5 25
UNITS A A
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All currents into pins are positive; all voltages are referenced to GND unless otherwise noted. Note 3: VCC maximum pin voltage is limited by input current. Since the VCC pin has an internal 6.5V shunt regulator, a low impedance supply
which exceeds 6V may exceed the rated terminal current. Operation from higher voltage supplies requires a series dropping resistor. See Applications Information. Note 4: Threshold voltages have no hysteresis unless the part is in comparator mode. Hysteresis is one-sided, affecting only invalid-to-valid transitions. See Applications Information.
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25C unless otherwise noted.
THRESHOLD VOLTAGE VARIATION (% OF 25C VALUE)
ADJ Threshold Voltage vs Temperature
508 THRESHOLD VOLTAGE, VRT (mV) 506 504 502 500 498 496 494 492 -50 -25 0 25 50 75 100 125 150 TEMPERATURE (C)
2919 G01
0.5 0 -0.5 -1.0 -1.5 -50 -25
REF VOLTAGE, VREF (V)
REF Output Load Regulation
0.6 0.4 0.2 0.0 TA = 125C -0.2 -0.4 -0.6 -1 -0.5 0 0.5 LOAD CURRENT (mA) 1
2919 G04
REF VOLTAGE VARIATION (% OF 2.5V SUPPLY AND 25C VALUE)
REF VOLTAGE, VARIATION (%OF NO LOAD AND 25C VALUE)
TA = 150C
TA = 150C
QUIESCENT SUPPLY CURRENT, ICC (A)
VCC = 2.5V
TA = 25C
TA = -40C
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VCC UVLO Threshold Variation vs Temperature
1.5 1.0 1.015 1.010 1.005 1.000
REF Output Voltage vs Temperature
IREF = 0A
0.995 0.990
0
25 50 75 100 125 150 TEMPERATURE (C)
2919 G02
0.985 -50 -25
0
25 50 75 100 125 150 TEMPERATURE (C)
2919 G03
REF Output Line Regulation
0.6 0.4 0.2 0.0 TA = 125C -0.2 -0.4 -0.6 2 3 4 5 SUPPLY VOLTAGE (V) 6
2919 G05
Quiescent Supply Current vs Temperature
90 80 70 60 50 VCC = 2.5V 40 30 20 -50 -25 VCC = 5V VCC = 3.3V ADJ1 = 0.55V ADJ2 = 0.45V SEL = OPEN
IREF = 0A
TA = 25C
TA = -40C
0
25 50 75 100 125 150 TEMPERATURE (C)
2919 G06
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LTC2919 TYPICAL PERFOR A CE CHARACTERISTICS
Propagation Delay vs Overdrive
700 600 PROPAGATION DELAY (s) 500 400 300 200 100 0 0.1 1 10 100 GLITCH PERCENTAGE PAST THRESHOLD (%)
2919 G07
RESET TIMEOUT PERIOD, tRST (ms)
RESET TIMEOUT PERIOD, tRST (ms)
Shunt Regulation Voltage vs Temperature
SHUNT REGULATION VOLTAGE, VCC(SHUNT) (V) SHUNT REGULATOR VOLTAGE, VCC(SHUNT) (V) 7.0 7.6
6.8 ICC = 10mA 6.6 ICC = 1mA 6.4 ICC = 100A 6.2
OUTPUT VOLTAGE (V)
6.0 -50 -25
0
25 50 75 100 125 150 TEMPERATURE (C)
2919 G10
OUT1, OUT2, RST Output Voltage vs VCC
0.4 OUTPUT PULL-DOWN CURRENT (mA) 6
OUTPUT PULL-DOWN CURRENT (mA)
OUTPUT VOLTAGE (V)
0.3 VCC 0.2 WITH 10k PULL-UP 0.1 WITH 100k PULL-UP 0 0 0.1 0.2 0.3 0.4 0.5 0.6 SUPPLY VOLTAGE, VCC (V) 0.7 0.8
UW
2919 G13
TA = 25C unless otherwise noted. Reset Timeout Period vs Temperature
260 240 220 200 EXTERNAL, CTMR = 22nF 180 160 140 -50 -25 INTERNAL
Reset Timeout Period vs Capacitance
10000
1000
100
10
1 0.1
1 10 100 TMR PIN CAPACITANCE, CTMR (nF)
1000
2919 G08
0
25 50 75 100 125 150 TEMPERATURE (C)
2919 G09
Shunt Regulation Voltage vs Supply Current
TA = 25C 5
OUT1, OUT2, RST Output Voltage vs VCC
ADJ1 = 0.55V ADJ2 = 0.45V 4 SEL = OPEN 10k PULL-UP R TO VCC 3
7.2
6.8
2 LTC2919-2.5 1 LTC2919-3.3 LTC2919-5
6.4
6.0 0.01
0 0.1 1 10 SUPPLY CURRENT, ICC (mA) 100
2919 G11
0
1
3 4 2 SUPPLY VOLTAGE, VCC (V)
5
2919 G12
OUT1, OUT2, RST Pull-Down Current vs VCC
ADJ1 = 0.45V ADJ2 = 0.55V 5 SEL = OPEN 4 OUTPUT AT 150mV 3 2 1 0 0 1 2 3 4 SUPPLY VOLTAGE, VCC (V) 5
2919 G14
OUT1, OUT2, RST Pull-Down Current vs VCC
1
OUTPUT AT 150mV 0.1
OUTPUT AT 50mV 0.01
0.001
OUTPUT AT 50mV
0.0001 0 0.2 0.4 0.6 0.8 SUPPLY VOLTAGE, VCC (V) 1
2919 G15
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LTC2919 TYPICAL PERFOR A CE CHARACTERISTICS
OUT1, OUT2, RST VOL vs Output Sink Current
1.0 VCC = 3V NO PULL-UP R 0.8 OUTPUT, VOL (V) TA = 150C -14 ISEL (A) TA = 125C -16 -18 -20 -22 -50 -25 ISEL (A) 0.6 TA = 25C 18 16 14 12 10 -50 -25 -10 -12
0.4 TA = -40C 0.2
0
0
5
15 20 25 10 OUTPUT SINK CURRENT (mA)
PI FU CTIO S (MSOP/DFN Package)
SEL (Pin 1): Input Polarity Select Three-State Input. Connect to VCC, GND or leave unconnected in open state to select one of three possible input polarity combinations (refer to Table 1). VCC (Pin 2): Power Supply. Bypass this pin to ground with a 0.1F (or greater) capacitor. Operates as a direct supply input for voltages up to 6V. Operates as a shunt regulator for supply voltages greater than 6V and should have a resistor between this pin and the supply to limit VCC input current to no greater than 10mA. When used without a current-limiting resistor, pin voltage must not exceed 6V. UVLO options allow VCC to be used as an accurate third fixed -10% UV supply monitor. OUT1 (Pin 3): Open-Drain Logic Output 1. Asserts low when positive polarity ADJ1 voltage is below threshold or negative polarity ADJ1 voltage is above threshold. Requires an external pull-up resistor and may be pulled above VCC. OUT2 (Pin 4): Open-Drain Logic Output 2. Asserts low when positive polarity ADJ2 voltage is below threshold or negative polarity ADJ2 voltage is above threshold. Requires an external pull-up resistor and may be pulled above VCC. RST (Pin 5): Open-Drain Inverted Reset Logic Output. Asserts low when any positive polarity input voltage is below threshold or any negative polarity input voltage is above threshold or VCC is below UVLO threshold. Held low for a timeout period after all voltage inputs are valid. Requires an external pull-up resistor and may be pulled above VCC. GND (Pin 6): Device Ground. REF (Pin 7): Buffered Reference Output. 1V nominal reference used for the offset of negative-monitoring applications. The buffered reference can source and sink up to 1mA. The reference can drive a capacitive load of up to 1000pF Larger capacitance may degrade transient . performance. This pin does not require a bypass capacitor, nor is one recommended. Leave open if unused. TMR (Pin 8): Reset Timeout Control. Attach an external capacitor (CTMR) to GND to set a reset timeout period of 9ms/nF A low leakage ceramic capacitor is recom. mended for timer accuracy. Capacitors larger than 1F (9 second timeout) are not recommended. See Applications Information for further details. Leaving this pin open generates a minimum timeout of approximately 400s. A 2.2nF capacitor will generate a 20ms timeout. Tying this pin to ground will enable the internal 200ms timeout. Tying this pin to VCC will disable the reset timer and put the part in comparator mode. Signals from the comparator outputs will then go directly to RST. ADJ2 (Pin 9): Adjustable Voltage Input 2. Input to voltage monitor comparator 2 (0.5V nominal threshold). The polarity of the input is selected by the state of the SEL pin (refer to Table 1). Tie to GND if unused (with SEL = GND or Open).
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2919 G16
TA = 25C unless otherwise noted. ISEL vs Temperature
22 20 SEL = VCC
ISEL vs Temperature
SEL = GND
30
0
25 50 75 100 125 150 TEMPERATURE (C)
2919 G17
0
25 50 75 100 125 150 TEMPERATURE (C)
2919 G18
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LTC2919 PI FU CTIO S (MSOP/DFN Package)
ADJ1 (Pin 10): Adjustable Voltage Input 1. Input to voltage monitor comparator 1 (0.5V nominal threshold). The polarity of the input is selected by the state of the SEL pin (refer to Table 1). Tie to REF if unused (with SEL = VCC or Open). Exposed Pad (Pin 11, DFN Only): The Exposed Pad may be left unconnected. For better thermal contact, tie to a PCB trace. This trace must be grounded or unconnected.
BLOCK DIAGRA
TI I G DIAGRA S
Positive Polarity Input Timing
VADJ VRT tPROP RST tPROP OUT 1V 1V tPROP VRT + VRT tRST
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SEL THREE-STATE DECODE CONTROL 2 CONTROL 1
VCC VCC 6.5V OUT1
ADJ1
+ -
TMR
VCC ADJUSTABLE PULSE GENERATOR EN
THREE-STATE DECODE RST
+ -
ADJ2
200ms PULSE GENERATOR
GND
+ - + -
500mV
OUT2
+
REF
+ - -
1.000V
SEL GND OPEN VCC
CONTROL 1 H L L
CONTROL 2 H H L
CONTROL = H = NEGATIVE POLARITY CONTROL = L = POSITIVE POLARITY
2919 BD
Negative Polarity Input Timing
VADJ
VRT tPROP
VRT - VRT tRST
RST tPROP OUT
1V tPROP 1V
UVLO Timing
VCC VCC(UVLO) tUV RST 1V tPROP OUT 1V
VCC(UVLO) + VCC(UVLO) tRST
NOTES: 1. VRT AND VCC(UVLO) = 0, except in Comparator Mode 2. IN COMPARATOR MODE, tRST = tPROP.
tPROP
2919 TD
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LTC2919 APPLICATIO S I FOR ATIO
The LTC2919 is a low power, high accuracy triple/dual supply monitor with two adjustable inputs and an accurate UVLO that can monitor a third supply. Reset timeout may be selected with an external capacitor, set to an internally generated 200ms, or disabled entirely. The three-state polarity select pin (SEL) chooses one of three possible polarity combinations for the adjustable input thresholds, as described in Table 1. An individual output is released when its corresponding ADJ input is valid (above threshold if configured for positive polarity, below threshold if configured for negative polarity). Both input voltages (VADJ1 and VADJ2) must be valid and VCC above the UVLO threshold for longer than the reset timeout period before RST is released. The LTC2919 asserts the reset output during power-up, power-down and brownout conditions on any of the voltage inputs. Power-Up The LTC2919 uses proprietary low voltage drive circuitry for the RST, OUT1 and OUT2 pins which holds them low with VCC as low as 200mV. This helps prevent indeterminate voltages from appearing on the outputs during power-up. In applications where the low voltage pull-down capability is important, the supply to which the external pull-up resistor connects should be the same supply which powers the part. Using the same supply for both ensures that RST, OUT1 and OUT2 never float above 200mV during power-up, as the pull-down ability of the pin will then increase as the required pull-down current to maintain a logic low increases. Once VCC passes the UVLO threshold, polarity selection and timer initialization will occur. If the monitored ADJ input is valid, the corresponding OUT will be released. When both ADJ1 and ADJ2 are valid, the appropriate timeout delay will begin, after which RST will be released. Power-Down On power-down, once VCC drops below the UVLO threshold or either VADJ becomes invalid, RST asserts logic low. VCC of at least 0.5V guarantees a logic low of 0.15V at RST.
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Shunt Regulator The LTC2919 contains an internal 6.5V shunt regulator on the VCC pin to allow operation from a high voltage supply. To operate the part from a supply higher than 6V, the VCC pin must have a current-limiting series resistor, RCC, to the supply. This resistor should be sized according to the following equation: VS(MAX) - 6.2V 10mA RCC VS(MIN) - 6.8V 200A + IREF where VS(MIN) and VS(MAX) are the operating minimum and maximum of the supply, and IREF is the maximum current the user expects to draw from the reference output. As an example, consider operation from an automobile battery which might dip as low as 10V or spike to 60V. Assume that the user will be drawing 100A from the reference. We must then pick a resistance between 5.4k and 10.7k. When the VCC pin is connected to a low impedance supply, it is important that the supply voltage never exceed 6V, or the shunt regulator may begin to draw large currents. Some supplies may have a nominal value sufficiently close to the shunt regulation voltage to prevent sizing of the resistor according to the above equation. For such supplies, a 470 series resistor may be used. Adjust Polarity Selection The external connection of the SEL pin selects the polarities of the LTC2919 adjustable inputs. SEL may be connected to GND, connected to VCC or left unconnected during normal operation. When left unconnected, the maximum leakage allowable from the pin is 5A. Table 1 shows the three possible selections of polarity based on SEL connection.
Table 1. Voltage Threshold Selection
ADJ1 INPUT Positive Polarity (+) UV or (-) OV Positive Polarity (+) UV or (-) OV Negative Polarity (-) UV or (+) OV ADJ2 INPUT Positive Polarity (+) UV or (-) OV Negative Polarity (-) UV or (+) OV Negative Polarity (-) UV or (+) OV SEL VCC Open Ground Note: Open = open circuit or driven by a three-state buffer in high impedance state with leakage current less than 5A.
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LTC2919 APPLICATIO S I FOR ATIO
If the user's application requires, the SEL pin may be driven using a three-state buffer which satisfies the VIL, VIH and leakage conditions of this three-state input pin. If the state of the SEL pin configures a given input as "negative polarity," the voltage at that ADJ pin must be below the trip point (0.5V nominal), or the corresponding OUT and RST output will be pulled low. Conversely, if a given input is configured as "positive polarity", the ADJ pin voltage must be above the trip point or the corresponding OUT and RST will assert low. Thus, a "negative polarity" input may be used to determine whether a monitored negative voltage is smaller in absolute value than it should be (-UV), or a monitored positive voltage is larger than it should be (+OV). The
Table 2a. Possible Combinations of Supply Monitoring. For Example Purposes, All Supplies are Monitored at 5% Tolerance and Connections are Shown Only for ADJ1, ADJ2, REF SEL, OUT1 and OUT2. Output Pull-up Resistors are Omitted for Clarity. ,
SEL = VCC
15V RP2A 309k RP2B 115k ADJ1 OUT1 ADJ2 OUT2 RP1A 11.5k RP1B 13.7k REF SEL UV (15V) UV (5V) RN1A 10.7k RN1B 13.3k REF SEL 5V -15V RN2A 309k
2 Positive UV
-15V RN2A 1.02M -5V RN2B 137k ADJ1 OUT1 ADJ2 OUT2 RN1A 30.9k RN1B 11.8k REF SEL OV (-15V) OV (-5V) RP1A 20k 15V RP2A 619k
2 Negative OV
15V RP2 309k -15V RN2 1.02M ADJ1 OUT1 ADJ2 OUT2 RP1 11.5k RN1 30.9k REF SEL UV (15V) OV (-15V) RP1 20k 15V RP2 619k
1 Positive UV, 1 Negative OV
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opposite is true for a "positive polarity" input (-OV or +UV). These polarity definitions are also shown in Table 1. For purposes of this data sheet, a negative voltage is considered "undervoltage" if it is closer to ground than it should be (e.g., -4.3V for a -5V supply). Proper configuration of the SEL pin and setting of the trip-points via external resistors allows for any two fault conditions to be detected. For example, the LTC2919 may monitor two supplies (positive, negative or one of each) for UV or for OV (or one UV and one OV). It may also monitor a single supply (positive or negative) for both UV and OV. Tables 2a and 2b show example configurations for monitoring possible combinations of fault condition and supply polarity.
SEL = GND
-5V RN2B 137k ADJ1 OUT1 ADJ2 OUT2 UV (-15V) UV (-5V)
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2 Negative UV
5V RP2B 133k ADJ1 OUT1 ADJ2 OUT2 RP1B 13.7k REF SEL OV (15V) 0V (5V)
2 Positive OV
-15V RN2 309k ADJ1 OUT1 ADJ2 OUT2 RN1 10.7k REF SEL OV (15V) UV (-15V)
1 Positive OV, 1 Negative UV
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LTC2919 APPLICATIO S I FOR ATIO
Table 2b. Possible Combinations of Supply Monitoring. For Example Purposes, All Supplies are Monitored at 5% Tolerance and Connections are Shown Only for ADJ1, ADJ2, REF SEL, OUT1 and OUT2. Output Pull-up Resistors are Omitted for Clarity. ,
SEL OPEN
15V RP6 2.37M RP5 10.7k RP4 76.8k REF SEL ADJ1 OUT1 ADJ2 OUT2 UV OV RN4 30.9k REF SEL RN5 4.02k -15V RN6 1.02M ADJ1 OUT1 ADJ2 OUT2 OV UV
1 Positive UV and OV
15V RP2 309k -15V RN2 309k ADJ1 OUT1 ADJ2 OUT2 RP1 11.5k RN1 10.7k REF SEL UV (15V) UV (-15V) RN1 30.9k
1 Positive UV, 1 Negative UV
15V RP2A 309k RP2B 133k ADJ1 OUT1 ADJ2 OUT2 RP1A 11.5k RP1B 13.7k REF SEL UV (15V) OV (5V) 5V
1 Positive UV, 1 Positive OV
Adjust Input Trip Point The trip threshold for the supplies monitored by the adjustable inputs is set with an external resistor divider, allowing the user complete control over the trip point. Selection of this trip voltage is crucial to the monitoring of the system. Any power supply has some tolerance band within which it is expected to operate (e.g., 5V 10%). It is generally undesirable that a supervisor issue a reset when the power supply is inside this tolerance band. Such a "nuisance" reset reduces reliability by preventing the system from functioning under normal conditions.
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1 Negative UV and OV
-15V RN2 1.02M 15V RP2 619k ADJ1 OUT1 ADJ2 OUT2 RP1 20k REF SEL OV (-15V) OV (15V)
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1 Negative OV, 1 Positive OV
-15V RN2A 1.02M -5V RN2B 137k ADJ1 OUT1 ADJ2 OUT2 RN1A 30.9k RN1B 13.3k REF SEL OV (-15V) UV (-5V)
1 Negative UV, 1 Negative OV
To prevent nuisance resets, the supervisor threshold must be guaranteed to lie outside the power supply tolerance band. To ensure that the threshold lies outside the power supply tolerance range, the nominal threshold must lie outside that range by the monitor's accuracy specification. All three of the LTC2919 inputs (ADJ1, ADJ2, VCC UVLO) have the same maximum threshold accuracy of 1.5% of the programmed nominal input voltage (over the full operating temperature range). Therefore, using the LTC2919, the typical 10% UV threshold is at 11.5% below the nominal input voltage level. For a 5V input, the threshold is nominally 4.425V. With 1.5% accuracy, the trip threshold range is
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LTC2919 APPLICATIO S I FOR ATIO
4.425V 75mV over temperature (i.e., 10% to 13% below 5V). The monitored system must thus operate reliably down to 4.35V or 13% below 5V over temperature. The above discussion is concerned only with the DC value of the monitored supply. Real supplies also have relatively high frequency variations from sources such as load transients, noise and pickup. The LTC2919 uses two techniques to combat spurious outputs toggling from high frequency variation. First, the timeout period helps prevent high frequency variation whose frequency is above 1/ tRST from appearing at the RST output. Second, the propagation delay versus overdrive function filters short glitches before the OUT1, OUT2 toggling or RST pulling low. When an ADJ becomes invalid, the corresponding OUT and RST pin assert low. When the supply recovers past the valid threshold, the reset timer starts (assuming it is not disabled) and RST does not go high until it finishes. If the supply becomes invalid any time during the timeout period, the timer resets and starts fresh when the supply next becomes valid. To reduce sensitivity of short glitches from toggling the output pins, the comparator outputs go through a lowpass filter before triggering the output logic. Any transient at the input of a comparator needs to be of sufficient magnitude and duration to pass the filter before it can change the monitor state. The combination of the reset timeout and comparator filtering prevents spurious changes in the output state without sacrificing threshold accuracy. If further supply glitch immunity is needed, the user may place an external capacitor from the ADJ input to ground. The resultant RC lowpass filter with the resistor divider will further reject high frequency components of the supply, at the cost of slowing the monitor's response to fault conditions. A common solution to the problem of spurious reset is to introduce hysteresis around the nominal threshold. However, this hysteresis degrades the effective accuracy of the monitor and increases the range over which the system must operate. The LTC2919 therefore does not have hysteresis, except in comparator mode (by tying TMR pin to VCC). If hysteresis is desired in other modes,
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it may be added externally. See 48V Telecom UV/OV with Hysteresis Applications on page 14 for an example. Selecting External Resistors In a typical positive supply monitoring application, the ADJx pin connects to a tap point on an external resistive divider between a positive voltage being monitored and ground, as shown in Figure 1. When monitoring a negative supply, the ADJx pin connects to a tap point on a resistive divider between the negative voltage being monitored and the buffered reference (REF), as shown in Figure 2.
VMON RP2 ADJx
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+ -
RP1
0.5V
+ -
2919 F01
Figure 1. Setting Positive Supply Trip Point
REF RN1 ADJx
+ -
RN2 VMON 0.5V
+ -
2919 F02
Figure 2. Setting Negative Supply Trip Point
Normally the user will select a desired trip voltage based on their supply and acceptable tolerances, and a value of RN1 or RP1 based on current draw. Current used by the resistive divider will be approximately: I= 0.5V 0.5V .OR = RP1 RN1
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11
LTC2919 APPLICATIO S I FOR ATIO
To minimize errors arising from ADJ input bias and to minimize loading on REF choose resistor RP1 (for positive supply monitoring) or RN1 (for negative supply monitoring) in the range of 5k to 100k. For a positive-monitoring application, RP2 is then chosen by: RP2 = RP1(2VTRIP - 1) For a negative-monitoring application: RN2 = RN1(1 - 2VTRIP) Note that the value VTRIP should be negative for a negative application. The LTC2919 can also be used to monitor a single supply for both UV and OV. This may be accomplished with three resistors, instead of the four required for two independent supplies. Configurations are shown in Figures 3 and 4. RP4 or RN4 may be chosen as is RP1 or RN1 above. For a given RP4, monitoring a positive supply: RP5 = RP4 VOV - VUV VUV VOV VUV
RP6 = RP4 ( 2VUV - 1)
For monitoring a negative supply with a given RN4: RN5 = RN4 VUV - VOV 1- VUV 1- VOV 1- VUV
LOGIC & OPEN DRAIN MOSFET OUT1
RN6 = RN4 (1- 2VUV )
ADJ1 VMON RP6
+ -
RP5
ADJ2
+ -
RP4
LOGIC & OPEN DRAIN MOSFET
OUT2
0.5V
+ -
2919 F03
Figure 3. Setting UV and OV Trip Point for a Positive Supply
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REF ADJ1
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+ -
RN4
LOGIC & OPEN DRAIN MOSFET
OUT1
OV
RN5
ADJ2
+ -
RN6 -VMON 0.5V
LOGIC & OPEN DRAIN MOSFET
OUT2
UV
+ -
2919 F04
Figure 4. Setting UV and OV Trip Point for a Negative Supply
For example, consider monitoring a -5V supply at 10%. For this supply application: VOV = -5.575V and VUV = -4.425V. Suppose we wish to consume about 5A in the divider, so RN4 = 100k. We then find RN5 = 21.0k, RN6 = 1.18M (nearest 1% standard values have been chosen).
VCC Monitoring/UVLO The LTC2919 contains an accurate third -10% undervoltage monitor on the VCC pin. This monitor is fixed at a nominal 11.5% below the VCC specified in the part number. The standard part (LTC2919-2.5) is configured to monitor a 2.5V supply (UVLO threshold of 2.213V), but versions to monitor 3.3V and 5.0V (UVLO of 2.921V and 4.425V, respectively) are available. For applications that do not need VCC monitoring, the 2.5V version should be used, and the UVLO will simply guarantee that the VCC is above the minimum required for proper threshold and timer accuracy before the timeout begins. Setting the Reset Timeout
UV
OV
RST goes high after a reset timeout period set by the TMR pin when the VCC and ADJ inputs are valid. This reset timeout may be configured in one of three ways: internal 200ms, programmed by external capacitor and no timeout (comparator mode). In externally-controlled mode, the TMR pin is connected by a capacitor to ground. The value of that capacitor allows for selection of a timeout ranging from about 400s to 9 seconds. See the following section for details.
LTC2919 APPLICATIO S I FOR ATIO
If the user wishes to avoid having an external capacitor, the TMR pin should be tied to ground, switching the part to an internal 200ms timer. If the user requires a shorter timeout than 400s, or wishes to perform application-specific processing of the reset output, the part may be put in comparator mode by tying the TMR pin to VCC. In comparator mode, the timer is bypassed and comparator outputs go straight to the reset output. The current required to hold TMR at ground or VCC is about 2.2A. To force the pin from the floating state to ground or VCC may require as much as 100A during the transition. When the part is in comparator mode, one of the two means of preventing false reset has been removed, so a small amount of one-sided hysteresis is added to the inputs to prevent oscillation as the monitored voltage passes through the threshold. This hysteresis is such that the valid-to-invalid transition threshold is unchanged, but the invalid-to-valid threshold is moved by about 0.7%. Thus, when the ADJ input polarity is positive, the threshold voltage is 500mV nominal when the input is above 500mV. As soon as the input drops below 500mV, the threshold moves up to 503.5mV nominal. Conversely, when configured as a negative-polarity input, the threshold is 500mV when the input is below 500mV, and switches to 496.5mV when the input goes above 500mV. The comparator mode feature is enabled by directly shorting the TMR pin to the VCC pin. Connecting the pin to any other voltage may have unpredictable results. Selecting the Reset Timing Capacitor Connecting a capacitor, CTMR, between the TMR pin and ground sets the reset timeout, tRST. The following formula approximates the value of capacitor needed for a particular timeout: CTMR = tRST * 110 [pF/ms] Leaving the TMR pin open with no external capacitor generates a reset timeout of approximately 400s.
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Maximum length of the reset timeout is limited by the ability of the part to charge a large capacitor on start-up. Initially, with a large (discharged) capacitor on the TMR pin, the part will assume it is in internal timer mode (since the pin voltage will be at ground). If the 2.2A flowing out of the TMR pin does not charge the capacitor to the ground-sense threshold within the first 200ms after supplies become good, the internal timer cycle will complete and RST will go high too soon. This imposes a practical limit of 1F (9 second timeout) if the length of timeout during power-up needs to be longer than 200ms. If the power-up timeout is not important, larger capacitors may be used, subject to the limitation that the capacitor leakage current must not exceed 500nA, or the function of the timer will be impaired. Output Pins Characteristics The DC characteristics of the OUT1, OUT2 and RST pulldown strength are shown in the Typical Performance Characteristics section. OUT1, OUT2 and RST are opendrain pins and thus require external pull-up resistors to the logic supply. They may be pulled above VCC, providing the absolute maximum rating of the pin are observed. As noted in the discussion of power up and power down, the circuits that drive OUT1, OUT2 and RST are powered by VCC. During a fault condition, VCC of at least 0.5V guarantees a VOL of 0.15V. The open-drain nature of the RST pin allows for wired-OR connection of several LTC2919s to monitor more than two supplies (see Typical Applications). Other logic with opendrain outputs may also connect to the RST line, allowing other logic-determined conditions to issue a reset.
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13
LTC2919 TYPICAL APPLICATIO S
Six Supply Undervoltage Monitor with 2.5V Reset Output and 20ms Timeout
15V 5V -5V -15V 3.3V 2.5V CBYP1 100nF RPU1 10k RPU2 10k RN2A 137k ADJ1 RN2B 309k RN1A 13.3k RN1B 10.7k ADJ2 TMR CTMR1 2.2nF OUT1 VCC SEL RST -5V_OK -15V_OK 5V_OK 15V_OK SEL RST LTC2919-2.5 REF RPU5 10k RPU3 10k VCC ADJ1 RP1A 13.7k RP1B 11.5k OUT1 ADJ2
2919 TA02
OUT2 GND
VIN 36V TO 72V RP2A 1.43M RP2A2 169k VUV(RISING): 43.3V VUV(FALLING): 38.7V VOV(RISING): 71.6V VOV(FALLING): 70.2V
M1, M2: FDG6301N OR SIMILAR
2919 TA03
MANUAL RESET PUSHBUTTON RN2 249k -12V
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SYSTEM
RPU4 10k
CBYP2 100nF
SYSTEM_OK RP2A 115k RP2B 309k
LTC2919-3.3 REF
OUT2 TMR GND
CTMR2 2.2nF
48V Telecom UV/OV Monitor with Hysteresis
SYSTEM RP2B 1.91M RCC 27k 0.25W CBYP 100nF 5V
M2 VCC ADJ1 RST LTC2919-2.5 ADJ2 RP1A 18.7k RP1B 13.7k M1 RP1B2 681k REF SEL GND OUT1 OUT2 TMR
RPU3 10k
PWRGD
RPU1 10k RPU2 10k
UV OV
12V UV Monitor Powered from 12V, 20ms Timeout (1.8V Logic Out)
RCC 10k 12V RP2 1.07M ADJ1 RP1 49.9k RN1 10.7k VCC RST CBYP 100nF 1.8V RPU3 10k RPU1 10k RPU2 10k
10k*
LTC2919-2.5 REF ADJ2 SEL GND OUT1
12V_OK OUT2 -12V_OK TMR CTMR 2.2nF
2919 TA01b
*OPTIONAL FOR ESD
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LTC2919 PACKAGE DESCRIPTIO U
DDB Package 10-Lead Plastic DFN (3mm x 2mm)
(Reference LTC DWG # 05-08-1722 Rev O)
0.64 0.05 (2 SIDES) 0.70 0.05 2.55 0.05 1.15 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC 2.39 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE PIN 1 BAR TOP MARK (SEE NOTE 6) 2.00 0.10 (2 SIDES) 0.64 0.05 (2 SIDES) 5 0.25 0.05 2.39 0.05 (2 SIDES) BOTTOM VIEW--EXPOSED PAD PIN 1 R = 0.20 OR 0.25 x 45 CHAMFER
(DDB10) DFN 0905 REV O
3.00 0.10 (2 SIDES)
R = 0.05 TYP
R = 0.115 TYP 6
0.40 0.10 10
1
0.200 REF
0.75 0.05
0.50 BSC
0 - 0.05
MS Package 10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661 Rev E)
3.00 0.102 (.118 .004) (NOTE 3) 10 9 8 7 6
0.497 0.076 (.0196 .003) REF
0.889 0.127 (.035 .005)
0.254 (.010) GAUGE PLANE
DETAIL "A" 0 - 6 TYP
4.90 0.152 (.193 .006)
3.00 0.102 (.118 .004) (NOTE 4)
5.23 (.206) MIN
3.20 - 3.45 (.126 - .136)
12345 0.53 0.152 (.021 .006) DETAIL "A" 0.18 (.007) SEATING PLANE 0.17 - 0.27 (.007 - .011) TYP 1.10 (.043) MAX 0.86 (.034) REF
0.50 0.305 0.038 (.0197) (.0120 .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT
NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
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0.50 (.0197) BSC
0.1016 0.0508 (.004 .002)
MSOP (MS) 0307 REV E
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC2919 TYPICAL APPLICATIO
+12V
Powered from 12V, +5VOUT is Sequenced to Start-up First, Followed by -5VOUT, with 5V UV Monitor, 200ms Timeout
RCC 4.7k CBYP 0.1F VCC LTC2919-2.5 ADJ1 RP1 13.7k RN1 13.3k ADJ2 OUT1 GND RST TMR REF SEL OUT2 RPU2 10k PWRGD RPU3 10k SYS_RESET
DC/DC CONVERTER
RN2 -5V 137k DC/DC CONVERTER SHDN
RELATED PARTS
PART NUMBER LTC1326/LTC1326-2.5 LTC1536 LTC1540 LTC1726-2.5/LTC1726-5 LTC1727/LTC1728 LTC1985-1.8 LTC2900 LTC2901 LTC2902 LTC2903 LTC2904/LTC2905 LTC2906/LTC2907 LTC2908 LTC2909 LTC2912-LTC2914 LTC2915-LTC2918 LT6700 DESCRIPTION Micropower Precision Triple Supply Monitor for 5V/2.5V, 3.3V and ADJ Precision Triple Supply Monitor for PCI Applications Nanopower Comparator with Reference Micropower Triple Supply Monitor for 2.5V/5V, 3.3V and ADJ Micropower Triple Supply Monitor with Open-Drain Reset Micropower Triple Supply Monitor with Push-Pull Reset Output Programmable Quad Supply Monitor Programmable Quad Supply Monitor Programmable Quad Supply Monitor Precision Quad Supply Monitor 3-State Programmable Precision Dual Supply Monitor Precision Dual Supply Monitor 1-Selectable and 1 Adjustable Precision Six Supply Monitor (Four Fixed and 2 Adjustable) Precision, Dual Input UV, OV and Negative Voltage Monitor Single/Dual/Quad UV and OV Voltage Monitors Single Voltage Monitor with 27 Unique Thresholds Micropower, Low Voltage, Dual Comparator with 400mV Reference COMMENTS 4.725V, 3.118V, 1V Threshold (0.75%) Meets PCI tFAIL Timing Specifications Adjustable Hysteresis Adjustable Reset and Watchdog Time-Outs Individual Monitor Outputs in MSOP/5-Lead SOT-23 5-Lead SOT-23 Package Adjustable Reset, 10-Lead MSOP and 3mm x 3mm 10-Lead DFN Package Adjustable Reset and Watchdog Timer, 16-Lead SSOP Package Adjustable Reset and Tolerance, 16-Lead SSOP Package, Margining Functions 6-Lead SOT-23 Package, Ultralow Voltage Reset Adjustable Tolerance and Reset Timer, 8-Lead SOT-23 Package Separate VCC Pin, RST/RST Outputs/Adjustable Reset Timer 8-Lead SOT-23 and DFN Packages 8-Lead SOT-23 and DFN Packages Separate VCC Pin, Adjustable Reset Timer, H-Grade Temperature Range Manual Reset, Watchdog, TSOT-8/MSOP-10 and 3mm x 2mm DFN Package, H-Grade Temperature Range 6-Lead SOT-23 Package
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16 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2008
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+5V +5V RP2 115k
2919 TA06
LT 0208 * PRINTED IN USA

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