View MAX6314US25D1-T_58862.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-1090; Rev 1; 1/99
68HC11/Bidirectional-Compatible P Reset Circuit
General Description
The MAX6314 low-power CMOS microprocessor (P) supervisory circuit is designed to monitor power supplies in P and digital systems. The MAX6314's RESET output is bidirectional, allowing it to be directly connected to Ps with bidirectional reset inputs, such as the 68HC11. It provides excellent circuit reliability and low cost by eliminating external components and adjustments. The MAX6314 also provides a debounced manual reset input. This device performs a single function: it asserts a reset signal whenever the VCC supply voltage falls below a preset threshold or whenever manual reset is asserted. Reset remains asserted for an internally programmed interval (reset timeout period) after VCC has risen above the reset threshold or manual reset is deasserted. The MAX6314 comes with factory-trimmed reset threshold voltages in 100mV increments from 2.5V to 5V. Preset timeout periods of 1ms, 20ms, 140ms, and 1120ms (minimum) are also available. The device comes in a SOT143 package. For a P supervisor with an open-drain reset pin, see the MAX6315 data sheet. o Small SOT143 Package o RESET Output Simplifies Interface to Bidirectional Reset I/Os o Precision Factory-Set VCC Reset Thresholds: 100mV Increments from 2.5V to 5V o 1.8% Reset Threshold Accuracy at TA = +25C o 2.5% Reset Threshold Accuracy Over Temp. o Four Reset Timeout Periods Available: 1ms, 20ms, 140ms, or 1120ms (minimum) o Immune to Short VCC Transients o 5A Supply Current o Pin-Compatible with MAX811
Features
MAX6314*
Ordering and Marking Information appears at end of data sheet.
________________________Applications
Computers Controllers Intelligent Instruments Critical P and C Power Monitoring Portable/Battery-Powered Equipment
VCC
Typical Operating Circuit
Pin Configuration
VCC
TOP VIEW
GND 1 4 VCC
LASERTRIMMED RESISTORS VCC
68HC11**
P
MAX6314
RESET CIRCUITRY 4.7k RESET MR RESET 2 3 MR RESET
MAX6314
GND
SOT143
**OR OTHER C/P WITH BIDIRECTIONAL RESET I/O PIN.
* Patents Pending
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
68HC11/Bidirectional-Compatible P Reset Circuit MAX6314
ABSOLUTE MAXIMUM RATINGS
VCC ........................................................................-0.3V to +6.0V All Other Pins..............................................-0.3V to (VCC + 0.3V) Input Current (VCC) .............................................................20mA Output Current (RESET)......................................................20mA Rate of Rise (VCC) ...........................................................100V/s Continuous Power Dissipation (TA = +70C) SOT143 (derate 4mW/C above +70C) .......................320mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10sec) .............................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +2.5V to +5.5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Operating Voltage Range VCC Supply Current Reset Threshold (Note 1) Reset Threshold Tempco VCC to Reset Delay Reset Timeout Period SYMBOL VCC ICC VTH VTH/C VCC = falling at 1mV/s MAX6314US_ _D1-T MAX6314US_ _D2-T MAX6314US_ _D3-T MAX6314US_ _D4-T 1 20 140 1120 0.8 2.4 0.3 x VCC 0.7 x VCC 1 100 500 32 VCC > 4.25V, ISINK = 3.2mA RESET Output Voltage VOL VCC > 2.5V, ISINK = 1.2mA VCC > 1.2V, ISINK = 0.5mA VCC > 1.0V, ISINK = 80A RESET INTERNAL PULL-UP Transition Flip-Flop Setup Time (Note 2) Active Pull-Up Enable Threshold RESET Active Pull-Up Current RESET Pull-Up Resistance RESET Output Rise Time (Note 3) tS VCC = 5V VCC = 5V CLOAD = 120pF CLOAD = 250pF CLOAD = 200pF CLOAD = 400pF 0.4 4.2 VCC = 3V tR VCC = 5V 20 4.7 400 0.9 5.2 333 666 333 666 63 100 0.4 0.3 0.3 0.3 ns V mA k V s ns ns k V CONDITIONS TA = 0C to +70C VCC = 5.5V, no load VCC = 3.6V, no load TA = +25C TA = -40C to +85C MIN 1.0 5 4 VTH 60 35 1.4 28 200 1570 TYP MAX 5.5 12 10 VTH + 1.8% VTH + 2.5% UNITS V A V ppm/C s 2 40 280 2240 ms
VTH - 1.8% VTH - 2.5%
tRP
MANUAL RESET INPUT MR Input Threshold MR Minimum Input Pulse MR Glitch Rejection MR to Reset Delay MR Pull-Up Resistance VIL VIH VIL VIH VTH > 4.0V VTH < 4.0V
ns V
Note 1: The MAX6314 monitors VCC through an internal, factory-trimmed voltage divider that programs the nominal reset threshold. Factory-trimmed reset thresholds are available in 100mV increments from 2.5V to 5V (see Ordering and Marking Information). Note 2: This is the minimum time RESET must be held low by an external pull-down source to set the active pull-up flip-flop. Note 3: Measured from RESET VOL to (0.8 x VCC), RLOAD = . 2 _______________________________________________________________________________________
68HC11/Bidirectional-Compatible P Reset Circuit
__________________________________________Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
PULL-UP CHARACTERISTICS
MAX6314-01
+5V 4.7k 74HC05
MAX6314
SUPPLY CURRENT vs. TEMPERATURE
MAX6314-02
6 4.7k PULL-UP 2V/div 5 SUPPLY CURRENT (A) 4 3 VCC = 3V 2 1 0 VCC = 1V VCC = 5V
100pF
+5V
74HC05
VCC RESET
MAX6314
MAX6314 PULL-UP 2V/div
100pF
MR
GND
INPUT 5V/div
200ns/div
-50
-30
-10
10
30
50
70
90
TEMPERATURE (C)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX6314-03
POWER-DOWN RESET DELAY vs. TEMPERATURE
MAX6314-04
NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE (VCC RISING)
NORMALIZED RESET TIMEOUT PERIOD 1.03 1.02 1.01 1.00 0.99 0.98 0.97 0.96
MAX6314-05
6 5 SUPPLY CURRENT (A) 4 3 TA = +25C 2 TA = -40C 1 0 0 1 2 3 4 5 SUPPLY VOLTAGE (V)
50 POWER-DOWN RESET DELAY (s) VCC FALLING AT 1mV/s 40 VTH = 4.63V 30 VTH = 3.00V
1.04
TA = +85C
20
10
0 -50 -30 -10 10 30 50 70 90 TEMPERATURE (C)
-50
-30
-10
10
30
50
70
90
TEMPERATURE (C)
NORMALIZED RESET THRESHOLD vs. TEMPERATURE (VCC FALLING)
MAX6314-06
MAXIMUM TRANSIENT DURATION vs. RESET COMPARATOR OVERDRIVE
MAX6314-07
RESET PULL-UP TIME vs. TEMPERATURE
MAX6314-08
1.006 NORMALIZED RESET THRESHOLD 1.004 1.002 1.000 0.998 0.996 0.994 -50 -30 -10 10 30 50 70
100 MAXIMUM TRANSIENT DURATION (s) TA = +25C RESET OCCURS ABOVE CURVE
600 500 CL = 390pF 400 300 200 CL = 100pF 100
60
VTH = 4.63V
40
20 VTH = 3.00V 0
RESET PULL-UP-TIME (ns)
80
0 10 100 1000 -50 -30 -10 10 30 50 70 90 RESET COMP. OVERDRIVE, VTH - VCC (mV) TEMPERATURE (C)
90
TEMPERATURE (C)
_______________________________________________________________________________________
3
68HC11/Bidirectional-Compatible P Reset Circuit MAX6314
______________________________________________________________Pin Description
PIN 1 2 NAME GND RESET Ground Active-Low Complementary Output. In addition to the normal N-channel pull-down, RESET has a P-channel pull-up transistor in parallel with a 4.7k resistor to facilitate connection to Ps with bidirectional resets. See the Reset Output section. Manual Reset Input. A logic low on MR asserts reset. Reset remains asserted as long as MR is low, and for the reset timeout period (tRP) after the reset conditions are terminated. Connect to VCC if not used. Supply Voltage and Reset Threshold Monitor Input FUNCTION
3 4
MR VCC
VCC
LASERTRIMMED RESISTORS
MAX6314
VREF
VCC
63k RESET GENERATOR VCC 2s ONE-SHOT TRANSITION FLIP-FLOP R FF S Q 4.7k MR
RESET
ACTIVE PULL-UP ENABLE COMPARATOR
0.5V
GND
Figure 1. Functional Diagram
4 _______________________________________________________________________________________
68HC11/Bidirectional-Compatible P Reset Circuit
_______________Detailed Description
The MAX6314 has a reset output consisting of a 4.7k pull-up resistor in parallel with a P-channel transistor and an N-channel pull down (Figure 1), allowing this IC to directly interface with microprocessors (Ps) that have bidirectional reset pins (see the Reset Output section). scratch. If, on the other hand, RESET is high after the two E-clock cycle delay, the processor knows that it caused the reset itself and can jump to a different vector and use stored state information to determine what caused the reset. The problem occurs with faster Ps; two E-clock cycles is only 500ns at 4MHz. When there are several devices on the reset line, the input capacitance and stray capacitance can prevent RESET from reaching the logic-high state (0.8 x VCC) in the allowed time if only a passive pull-up resistor is used. In this case, all resets will be interpreted as external. The P is guaranteed to sink only 1.6mA, so the rise time cannot be much reduced by decreasing the recommended 4.7k pull-up resistance. The MAX6314 solves this problem by including a pullup transistor in parallel with the recommended 4.7k resistor (Figure 1). The pull-up resistor holds the output high until RESET is forced low by the P reset I/O, or by the MAX6314 itself. Once RESET goes below 0.5V, a comparator sets the transition edge flip-flop, indicating that the next transition for RESET will be low to high. As soon as RESET is released, the 4.7k resistor pulls RESET up toward VCC. When RESET rises above 0.5V, the active P-channel pull-up turns on for the 2s duration of the one-shot. The parallel combination of the 4.7k pull-up and the P-channel transistor onresistance quickly charges stray capacitance on the reset line, allowing RESET to transition low to high within the required two E-clock period, even with several devices on the reset line (Figure 2). Once the one-shot times out, the P-channel transistor turns off. This process occurs regardless of whether the reset was caused by VCC dipping below the reset threshold, MR being asserted, or the P or other device asserting RESET. Because the MAX6314 includes the standard 4.7k pull-up resistor, no external pull-up resistor is required. To minimize current consumption, the internal pull-up resistor is disconnected whenever the MAX6314 asserts RESET.
MAX6314
Reset Output
A P's reset input starts the P in a known state. The MAX6314 asserts reset to prevent code-execution errors during power-up, power-down, or brownout conditions. RESET is guaranteed to be a logic low for VCC > 1V (see the Electrical Characteristics). Once V CC exceeds the reset threshold, the internal timer keeps reset asserted for the reset timeout period (tRP); after this interval RESET goes high. If a brownout condition occurs (monitored voltage dips below its programmed reset threshold), RESET goes low. Any time VCC dips below the reset threshold, the internal timer resets to zero and RESET goes low. The internal timer starts when VCC returns above the reset threshold, and RESET remains low for the reset timeout period. The MAX6314's RESET output is designed to interface with Ps that have bidirectional reset pins, such as the Motorola 68HC11. Like an open-drain output, the MAX6314 allows the P or other devices to pull RESET low and assert a reset condition. However, unlike a standard open-drain output, it includes the commonly specified 4.7k pull-up resistor with a P-channel active pull-up in parallel. This configuration allows the MAX6314 to solve a problem associated with Ps that have bidirectional reset pins in systems where several devices connect to RESET. These Ps can often determine if a reset was asserted by an external device (i.e., the supervisor IC) or by the P itself (due to a watchdog fault, clock error, or other source), and then jump to a vector appropriate for the source of the reset. However, if the P does assert reset, it does not retain the information, but must determine the cause after the reset has occurred. The following procedure describes how this is done with the Motorola 68HC11. In all cases of reset, the P pulls RESET low for about four E-clock cycles. It then releases RESET, waits for two E-clock cycles, then checks RESET's state. If RESET is still low, the P concludes that the source of the reset was external and, when RESET eventually reaches the high state, jumps to the normal reset vector. In this case, stored state information is erased and processing begins from
Manual Reset Input
Many P-based products require manual reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset. A logic low on MR asserts reset. Reset remains asserted while MR is low, and for the reset active timeout period after MR returns high. To minimize current consumption, the internal 4.7k pull-up resistor on RESET is disconnected whenever RESET is asserted.
_______________________________________________________________________________________
5
68HC11/Bidirectional-Compatible P Reset Circuit MAX6314
VCC VCC 68HC11 4.7k RESET RESET CIN
MR
RESET CIRCUITRY CIN
RESET CIRCUITRY
CSTRAY
MAX6314
RESET CIN OTHER DEVICES
Figure 2. MAX6314 Supports Additional Devices on the Reset Bus
MR has an internal 63k pull-up resistor, so it can be left open if not used. Connect a normally open momentary switch from MR to GND to create a manual reset function; external debounce circuitry is not required. If MR is driven from long cables or if the device is used in a noisy environment, connecting a 0.1F capacitor from MR to ground provides additional noise immunity.
__________Applications Information
Negative-Going VCC Transients In addition to issuing a reset to the P during power-up, power-down, and brownout conditions, these devices are relatively immune to short-duration negative-going transients (glitches). The Typical Operating Characteristics show the Maximum Transient Duration vs. Reset Threshold Overdrive, for which reset pulses are not generated. The graph was produced using negativegoing pulses, starting at VRST max and ending below the programmed reset threshold by the magnitude indicated (reset threshold overdrive). The graph shows the maximum pulse width that a negative-going V CC transient may typically have without causing a reset pulse to be issued. As the amplitude of the transient increases (i.e., goes farther below the reset threshold), the maximum allowable pulse width decreases. A 0.1F bypass capacitor mounted close to VCC provides additional transient immunity.
When V CC falls below 1V, RESET no longer sinks current--it becomes an open circuit. Therefore, highimpedance CMOS-logic inputs connected to RESET can drift to undetermined voltages. This presents no problem in most applications, since most P and other circuitry is inoperative with VCC below 1V. However, in applications where RESET must be valid down to VCC = 0V, adding a pull-down resistor to RESET will cause any stray leakage currents to flow to ground, holding RESET low (Figure 3). R1's value is not critical; 100k is large enough not to load RESET and small enough to pull RESET to ground.
Ensuring a Valid RESET Output Down to VCC = 0V
VCC
MAX6314
RESET
R1 GND
Figure 3. RESET Valid to VCC = Ground Circuit
6
_______________________________________________________________________________________
68HC11/Bidirectional-Compatible P Reset Circuit MAX6314
VCC RESET 0.5V tS RESET PULLED LOW BY C OR RESET GENERATOR tRP OR C RESET DELAY tR 0.8 x VCC
ACTIVE PULL-UP TURNS ON
Figure 4. RESET Timing Diagram
__________________________________________Ordering and Marking Information
PART MAX6314US50D1-T MAX6314US49D1-T MAX6314US48D1-T MAX6314US47D1-T MAX6314US46D1-T MAX6314US45D1-T MAX6314US44D1-T MAX6314US43D1-T MAX6314US42D1-T MAX6314US41D1-T MAX6314US40D1-T MAX6314US39D1-T MAX6314US38D1-T MAX6314US37D1-T MAX6314US36D1-T MAX6314US35D1-T MAX6314US34D1-T MAX6314US33D1-T MAX6314US32D1-T MAX6314US31D1-T MAX6314US30D1-T MAX6314US29D1-T NOMINAL VTH (V) 5.00 4.90 4.80 4.70 4.63 4.50 4.39 4.30 4.20 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40 3.30 3.20 3.08 3.00 2.93 MIN tRP (ms) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 PKG. TOP MARK AA_ _ AB_ _ AC_ _ AD_ _ AE_ _ AF_ _ AG_ _ AH_ _ AI_ _ AJ_ _ AK_ _ AL_ _ CA_ _ CB_ _ CC_ _ CD_ _ CE_ _ CF_ _ CG_ _ CH_ _ CI_ _ CJ_ _ PART MAX6314US28D1-T MAX6314US27D1-T MAX6314US26D1-T MAX6314US25D1-T MAX6314US50D2-T MAX6314US49D2-T MAX6314US48D2-T MAX6314US47D2-T MAX6314US46D2-T MAX6314US45D2-T MAX6314US44D2-T MAX6314US43D2-T MAX6314US42D2-T MAX6314US41D2-T MAX6314US40D2-T MAX6314US39D2-T MAX6314US38D2-T MAX6314US37D2-T MAX6314US36D2-T MAX6314US35D2-T MAX6314US34D2-T MAX6314US33D2-T NOMINAL VTH (V) 2.80 2.70 2.63 2.50 5.00 4.90 4.80 4.70 4.63 4.50 4.39 4.30 4.20 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40 3.30 MIN tRP (ms) 1 1 1 1 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 PKG. TOP MARK CK_ _ CL_ _ CM_ _ CN_ _ CO_ _ CP_ _ CQ_ _ CR_ _ CS_ _ CT_ _ CU_ _ CV_ _ CW_ _ CX_ _ CY_ _ CZ_ _ DA_ _ DB_ _ DC_ _ DD_ _ DE_ _ DJ_ _
The MAX6314 is available in a SOT143 package, -40C to +85C temperature range. The first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code. Sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities.
Non-bolded products have 10,000 piece minimum-order quantities. Contact factory for details.
Note: All devices available in tape-and-reel only. Contact factory for availability.
_______________________________________________________________________________________
7
68HC11/Bidirectional-Compatible P Reset Circuit MAX6314
_____________________________Ordering and Marking Information (continued)
PART MAX6314US32D2-T MAX6314US31D2-T MAX6314US30D2-T MAX6314US29D2-T MAX6314US28D2-T MAX6314US27D2-T MAX6314US26D2-T MAX6314US25D2-T MAX6314US50D3-T MAX6314US49D3-T MAX6314US48D3-T MAX6314US47D3-T MAX6314US46D3-T MAX6314US45D3-T MAX6314US44D3-T MAX6314US43D3-T MAX6314US42D3-T MAX6314US41D3-T MAX6314US40D3-T MAX6314US39D3-T MAX6314US38D3-T MAX6314US37D3-T MAX6314US36D3-T MAX6314US35D3-T MAX6314US34D3-T MAX6314US33D3-T MAX6314US32D3-T MAX6314US31D3-T MAX6314US30D3-T MAX6314US29D3-T NOMINAL VTH (V) 3.20 3.08 3.00 2.93 2.80 2.70 2.63 2.50 5.00 4.90 4.80 4.70 4.63 4.50 4.39 4.30 4.20 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40 3.30 3.20 3.08 3.00 2.93 MIN tRP (ms) 20 20 20 20 20 20 20 20 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 140 PKG. TOP MARK DK_ _ DL_ _ DM_ _ DN_ _ DO_ _ DP_ _ DQ_ _ DR_ _ DS_ _ DT_ _ DU_ _ DV_ _ DW_ _ DX_ _ DY_ _ DZ_ _ EA_ _ EB_ _ EC_ _ EG_ _ EH_ _ EI_ _ EJ_ _ EK_ _ EL_ _ EM_ _ EN_ _ EO_ _ EP_ _ ES_ _ PART MAX6314US28D3-T MAX6314US27D3-T MAX6314US26D3-T MAX6314US25D3-T MAX6314US50D4-T MAX6314US49D4-T MAX6314US48D4-T MAX6314US47D4-T MAX6314US46D4-T MAX6314US45D4-T MAX6314US44D4-T MAX6314US43D4-T MAX6314US42D4-T MAX6314US41D4-T MAX6314US40D4-T MAX6314US39D4-T MAX6314US38D4-T MAX6314US37D4-T MAX6314US36D4-T MAX6314US35D4-T MAX6314US34D4-T MAX6314US33D4-T MAX6314US32D4-T MAX6314US31D4-T MAX6314US30D4-T MAX6314US29D4-T MAX6314US28D4-T MAX6314US27D4-T MAX6314US26D4-T MAX6314US25D4-T NOMINAL VTH (V) 2.80 2.70 2.63 2.50 5.00 4.90 4.80 4.70 4.63 4.50 4.39 4.30 4.20 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40 3.30 3.20 3.08 3.00 2.93 2.80 2.70 2.63 2.50 MIN tRP (ms) 140 140 140 140 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 1120 PKG. TOP MARK ET_ _ EU_ _ EV_ _ EW_ _ EX_ _ EY_ _ EZ_ _ FA_ _ FB_ _ FC_ _ FD_ _ FE_ _ FF_ _ FG_ _ FH_ _ FI_ _ FJ_ _ FK_ _ FL_ _ FM_ _ FN_ _ FO_ _ FP_ _ FQ_ _ FR_ _ FS_ _ FT_ _ FU_ _ FV_ _ FW_ _
The MAX6314 is available in a SOT143 package, -40C to +85C temperature range. The first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code. Sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities.
Non-bolded products have 10,000 piece minimum-order quantities. Contact factory for details.
Note: All devices available in tape-and-reel only. Contact factory for availability.
Chip Information
TRANSISTOR COUNT: 519
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX6314US25D1-T

	To Download MAX6314US25D1-T Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .