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ISL4238E, ISL4244E, ISL4245E
Data Sheet November 2002 FN8038.2
QFN Packaged, 15kV ESD Protected, +2.7V to +5.5V, 10Nanoamp, 250kbps/ 1Mbps, RS-232 Transceivers with Enhanced Automatic Powerdown
The Intersil ISL4238E/44E/45E devices are 2.7V to 5.5V powered RS-232 transmitters/receivers which meet ElA/TIA-232 and V.28/V.24 specifications, even at VCC = 3.0V. Additionally, they provide 15kV ESD protection (IEC6100-4-2 Air Gap and Human Body Model) on transmitter outputs and receiver inputs (RS-232 pins). Targeted applications are PDAs, Palmtops, and notebook and laptop computers where the low operational, and even lower standby, power consumption is critical. Efficient onchip charge pumps, coupled with manual and enhanced automatic powerdown functions, reduce the standby supply current to a 10nA trickle. Tiny 5mm x 5mm Quad Flat NoLead (QFN) packaging and the use of small, low value capacitors ensure board space savings as well. Data rates greater than 250kbps (ISL4238E/44E) / 1Mbps (ISL4245E) are guaranteed at worst case load conditions. The ISL424XE are 3 driver, 5 receiver (DTE) devices that, coupled with the QFN package, provide the industry's smallest, lowest power complete serial port suitable for PDAs, and laptop or notebook computers. The 5x5 QFN requires 60% less board area than a 28 lead TSSOP, and is nearly 20% thinner. The devices also include a noninverting always-active receiver for "wake-up" capability. The ISL4238E is a 5 driver, 3 receiver device optimized for DCE applications with full hardware handshaking. It also includes a noninverting always-active receiver for RING INDICATOR monitoring. Transmitter and logic inputs include active feedback resistors that retain the input state once driven to a valid logic level. These devices feature an enhanced automatic powerdown function which powers down the on-chip powersupply and driver circuits. This occurs when all receiver and transmitter inputs detect no signal transitions for a period of 30sec. These devices power back up, automatically, whenever they sense a transition on any transmitter or receiver input. Table 1 summarizes the features of the ISL4238E/4XE, while Application Note AN9863 summarizes the features of each device comprising the 3V RS-232 family.
Features
* Parameters Fully Specified for 10% Tolerance Supplies and Full Industrial Temp Range * Available in Small QFN (5mm x 5mm) Package which is 60% Smaller than a 28 Lead TSSOP * ESD Protection for RS-232 I/O Pins to 15kV (IEC6100) * DTE (ISL4244E/45E) and DCE (ISL4238E) Versions * Lowest Supply Current in Powerdown . . . . . . . . . . . .10nA * Active Feedback Resistors on TX and Logic Inputs (ISL4238E) * Flow Through Pinouts * Manual and Enhanced Automatic Powerdown Features * Guaranteed Minimum Data Rate 250kbps (ISL4238E/44E) / 1Mbps (ISL4245E) * Latch-Up Free * On-Chip Charge Pumps Require Only Four External 0.1F Capacitors * Wide Power Supply Range . . . . . . Single +2.7V to +5.5V * Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V * RS-232 Compatible with VCC = 2.7V
Applications
* Any Space Constrained System Requiring RS-232 Ports - Battery Powered, Hand-Held, and Portable Equipment - Laptop Computers, Notebooks - PDAs and Palmtops, Data Cables - Cellular/Mobile Phones, Digital Cameras, GPS Receivers
Related Literature
* Technical Brief TB363 "Guidelines for Handling and Processing Moisture Sensitive Surface Mount Devices" * Technical Brief TB379 "Thermal Characterization of Packages for ICs" * Technical Brief TB389 "PCB Land Pattern Design and Surface Mount Guidelines for QFN Packages"
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright (c) Intersil Americas Inc. 2002. All Rights Reserved All other trademarks mentioned are the property of their respective owners.
ISL4238E, ISL4244E, ISL4245E
TABLE 1. SUMMARY OF FEATURES NO. OF MONITOR Rx. (ROUTB) 1 1 1 DATA RATE (kbps) 250 250 1000 MANUAL POWERDOWN? YES YES YES ENHANCED AUTOMATIC POWERDOWN FUNCTION? YES YES YES
PART NUMBER ISL4238E ISL4244E ISL4245E
NO. OF NO. OF Tx. Rx. 5 3 3 3 5 5
CONFIG. DCE DTE DTE
QFN PKG. 5x5 5x5 5x5
Rx. ENABLE FUNCTION? NO NO NO
Ordering Information
PART NO. (BRAND) ISL4238EIR (4238EIR) ISL4238EIR-T (4238EIR) ISL4244EIR (4244EIR) TEMP. RANGE (oC) -40 to 85 -40 to 85 -40 to 85 PACKAGE 32 Ld QFN Tape & Reel 32 Ld QFN PKG. NO. L32.5x5 L32.5x5 L32.5x5
Ordering Information (Continued)
PART NO. (BRAND) ISL4244EIR-T (4244EIR) ISL4245EIR (4245EIR) ISL4245EIR-T (4245EIR) TEMP. RANGE (oC) -40 to 85 -40 to 85 -40 to 85 PACKAGE Tape & Reel 32 Ld QFN Tape & Reel PKG. NO. L32.5x5 L32.5x5 L32.5x5
Pinouts
ISL4238E (QFN) TOP VIEW
GND VCC C2+ C1+ C2NC V+ V-
ISL4244E, ISL4245E (QFN) TOP VIEW
VCC 26 C2+ C1+ C2-
NC
32 T1OUT T2OUT T3OUT R1IN R2IN T4OUT R3IN T5OUT 1 2 3 4 5 6 7 8 9 NC
31
30
29
28
27
26
25 24 23 22 21 20 19 18 17 C1T1IN T2IN T3IN R1OUT R2OUT T4IN R3OUT R1IN R2IN R3IN R4IN R5IN T1OUT T2OUT T3OUT 1 2 3 4 5 6 7 8
32
31
30
29
28
V+
V-
27
25 24 23 22 21 20 19 18 17 GND C1FORCEON FORCEOFF INVALID R2OUTB R1OUT R2OUT
10 FORCEON
11 FORCEOFF
12 INVALID
13 NC
14 R1OUTB
15 T5IN
16 NC
9 NC
10 T3IN
11 T2IN
12 T1IN
13 R5OUT
14 R4OUT
15 R3OUT
16 NC
2
NC
ISL4238E, ISL4244E, ISL4245E Pin Descriptions
PIN VCC V+ VGND C1+ C1C2+ C2TIN TOUT RIN ROUT ROUTB INVALID System power supply input (2.7V to 5.5V). Internally generated positive transmitter supply (+5.5V). Internally generated negative transmitter supply (-5.5V). Ground connection. External capacitor (voltage doubler) is connected to this lead. External capacitor (voltage doubler) is connected to this lead. External capacitor (voltage inverter) is connected to this lead. External capacitor (voltage inverter) is connected to this lead. TTL/CMOS compatible transmitter Inputs. (Note 1) 15kV ESD Protected, RS-232 level (nominally 5.5V) transmitter outputs. 15kV ESD Protected, RS-232 compatible receiver inputs. TTL/CMOS level receiver outputs. TTL/CMOS level, noninverting, always enabled receiver outputs. Active low output that indicates if no valid RS-232 levels are present on any receiver input. FUNCTION
FORCEOFF Active low to shut down transmitters and on-chip power supply. This overrides any automatic circuitry and FORCEON (see Table 2). FORCEON NOTE: 1. ISL4238E input pins incorporate positive feedback resistors. Once the input is driven to a valid logic level, the feedback resistor maintains that logic level until VCC is removed. Unused transmitter inputs may be left unconnected by the user. Active high input to override automatic powerdown circuitry thereby keeping transmitters active. (FORCEOFF must be high).
3
ISL4238E, ISL4244E, ISL4245E Typical Operating Circuits
ISL4238E
+3.3V + C1 0.1F NOTE 2 C2 0.1F 0.1F 28 + 24 C1+
26 VCC 27 V+ 32 + C3 0.1F NOTE 2 C4 0.1F +
C129 C2+ + 31 C223 T1
V-
1 T1OUT
T1IN 22 T2IN 21 T3IN 18 T4IN 15 T5IN TTL/CMOS LOGIC LEVELS T5 8 T4 6 T3 3 T2 2
T2OUT
T3OUT
RS-232 LEVELS
T4OUT
T5OUT 14
R1OUTB 20 R1OUT R1 19 R2OUT R2 17 R3OUT R3 10 FORCEON VCC 11 FORCEOFF 12 INVALID GND 30 5k 5k 7 R3IN 5k 5 R2IN RS-232 LEVELS 4 R1IN
TO POWER CONTROL LOGIC
NOTE: 2. For VCC = 3.15V (3.3V -5%), use C1 - C4 = 0.1F or greater. For VCC = 3.0V (3.3V -10%), use C1 - C4 = 0.22F or greater.
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ISL4238E, ISL4244E, ISL4245E Typical Operating Circuits (Continued)
ISL4244E, ISL4245E
+3.3V + 0.1F 28 + 23 C1+
26 VCC 27 V+ 31 + C3 0.1F
C1 0.1F C2 0.1F
C129 C2+ + 30 C212 T1
V-
C4 0.1F + T1OUT
6
T1IN 11 T2IN 10 T3IN 19 R2OUTB TTL/CMOS LOGIC LEVELS 18 R1OUT R1 17 R2OUT R2 15 R3OUT R3 14 R4OUT R4 13 R5OUT 22 R5 FORCEON 5k 5k 5 5k 4 5k 3 5k 2 1 T3 8 T2 7
T2OUT
RS-232 LEVELS
T3OUT
R1IN
R2IN
R3IN
RS-232 LEVELS
R4IN
R5IN
VCC TO POWER CONTROL LOGIC
21 FORCEOFF 20 INVALID GND 24
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ISL4238E, ISL4244E, ISL4245E
Absolute Maximum Ratings
VCC to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V V+ to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V V- to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V Input Voltages TIN, FORCEOFF, FORCEON . . . . . . . . . . . . . . . . . . -0.3V to 6V RIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25V Output Voltages TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2V ROUT, INVALID . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VCC +0.3V Short Circuit Duration TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table
Thermal Information
Thermal Resistance (Typical, Note 3)
JA (oC/W)
32 Ld QFN Package. . . . . . . . . . . . . . . . . . . . . . . . . 32 Moisture Sensitivity (see Technical Brief TB363) QFN Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level 1 Maximum Junction Temperature (Plastic Package) . . . . . . . 150oC Maximum Storage Temperature Range . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300oC
Operating Conditions
Temperature Range ISL42XXEIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to 85oC
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE: 3. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with "direct attach" features. See Tech Brief TB379, and Tech Brief TB389.
Electrical Specifications
Test Conditions: ISL4238E VCC = 3.15V to 5.5V, C1 - C4 = 0.1F; VCC = 3V, C1 - C4 = 0.22F; ISL424XE VCC = 3V to 5.5V, C1 - C4 = 0.1F; Unless Otherwise Specified. Typicals are at TA = 25oC TEST CONDITIONS TEMP (oC) MIN TYP MAX UNITS
PARAMETER DC CHARACTERISTICS Operating Voltage Range Supply Current, Automatic Powerdown Supply Current, Powerdown
Full All RIN Open, FORCEON = GND, FORCEOFF = VCC 25 Full All RIN Open, FORCEOFF = GND 25 Full
2.7 -
3 50
5.5 300 300 300 300 1.0 1.5
V nA nA nA nA mA mA
-
3 50
Supply Current, Automatic Powerdown Disabled
All Outputs Unloaded, FORCEON = FORCEOFF = VCC, VCC = 3.0V
25 Full
-
0.3 0.3
LOGIC AND TRANSMITTER INPUTS AND RECEIVER OUTPUTS Input Logic Threshold Low Input Logic Threshold High Transmitter Input Hysteresis Input Leakage Current Output Leakage Current Output Voltage Low Output Voltage High RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current VOUT = 12V, VCC = 0V or 3V to 5.5V, Automatic Powerdown or FORCEOFF = GND All Transmitter Outputs Loaded with 3k to Ground VCC = V+ = V- = 0V, Transmitter Output = 2V Full Full Full Full 5.0 300 5.4 10M 35 60 25 V mA A VCC = 3.0V VCC = 3.6V Full Full Full 25 Full -25 2.4 3 1.0 1.5 0.5 5 25 0.6 7 V V V V k TIN, FORCEON, FORCEOFF (ISL4238E, Note 4) FORCEOFF = GND IOUT = 1.6mA IOUT = -1.0mA TIN, FORCEON, FORCEOFF TIN, FORCEON, FORCEOFF, VCC = 3.6V Full Full 25 Full Full Full Full 2.0 0.5 0.01 0.05 0.8 1.0 10 0.4 V V V A A V V
VCC -0.6 VCC -0.1
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ISL4238E, ISL4244E, ISL4245E
Electrical Specifications
Test Conditions: ISL4238E VCC = 3.15V to 5.5V, C1 - C4 = 0.1F; VCC = 3V, C1 - C4 = 0.22F; ISL424XE VCC = 3V to 5.5V, C1 - C4 = 0.1F; Unless Otherwise Specified. Typicals are at TA = 25oC TEST CONDITIONS TEMP (oC) MIN TYP MAX UNITS
PARAMETER
ENHANCED AUTOMATIC POWERDOWN (FORCEON = GND, FORCEOFF = VCC) Receiver Input Thresholds to INVALID High Receiver Input Thresholds to INVALID Low INVALID, Output Voltage Low INVALID, Output Voltage High Receiver Positive or Negative Threshold to INVALID High Delay (tINVH) Receiver Positive or Negative Threshold to INVALID Low Delay (tINVL) Receiver Positive or Negative Threshold to INVALID Low Delay (tINVL) Receiver or Transmitter Edge to Transmitters Enabled Delay (tWU) Receiver or Transmitter Edge to Transmitters Disabled Delay (tAUTOPWDN) TIMING CHARACTERISTICS Maximum Data Rate ISL4238E/44E Maximum Data Rate ISL4245E RL = 3k, CL = 1000pF, One Transmitter Switching RL = 3k, One Transmitter CL = 1000pF Switching VCC = 3V to 4.5V, CL = 250pF VCC = 4.5V to 5.5V, CL = 1000pF Receiver Propagation Delay Receiver Input to Receiver tPHL Output, CL = 150pF tPLH Full Full Full Full 25 Full 25 Full Receiver Skew tPHL - tPLH, CL = 150pF 25 Full Transmitter Propagation Delay ISL4238E/44E Transmitter Input to Transmitter Output, CL = 1000pF, RL = 3k tPHL 25 Full tPLH 25 Full Transmitter Skew ISL4238E/44E tPHL - tPLH (Note 7), RL = 3k, CL = 1000pF 25 Full Transmitter Propagation Delay ISL4245E Transmitter Input to Transmitter Output, CL = 1000pF, RL = 3k tPHL 25 Full tPLH 25 Full Transmitter Skew ISL4245E tPHL - tPLH (Note 6), RL = 3k, CL = 1000pF 25 Full 250 250 1000 1000 500 900 2000 1500 0.15 0.2 0.3 0.35 120 150 0.75 0.85 0.8 0.9 50 100 0.4 0.5 0.35 0.4 50 60 0.3 0.35 0.5 0.55 250 300 1 1.1 1 1.1 200 250 0.8 0.8 0.7 0.7 200 250 kbps kbps kbps kbps s s s s ns ns s s s s ns ns s s s s ns ns ISL4238E See Figure 6 See Figure 6 IOUT = 1.6mA IOUT = -1.0mA Full Full Full Full 25 Full 25 Full ISL4244E/45E 25 Full Note 5 Note 5 Full Full 15 -2.7 -0.3 VCC-0.6 0.5 0.9 60 100 30 40 20 30 2.7 0.3 0.4 1 1.5 100 150 50 60 100 60 V V V V s s s s s s s sec
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ISL4238E, ISL4244E, ISL4245E
Electrical Specifications
Test Conditions: ISL4238E VCC = 3.15V to 5.5V, C1 - C4 = 0.1F; VCC = 3V, C1 - C4 = 0.22F; ISL424XE VCC = 3V to 5.5V, C1 - C4 = 0.1F; Unless Otherwise Specified. Typicals are at TA = 25oC TEST CONDITIONS Normal Operation, RL = 1k to 0.5VCC, CL = 15pF TEMP (oC) 25 Full Receiver Output Disable Time Normal Operation, RL = 1k to 0.5VCC, CL = 15pF 25 Full Transmitter Output Enable Time ISL4238E/44E/45E Transmitter Output Disable Time ISL4238E/44E/45E Transition Region Slew Rate ISL4238E/44E Normal Operation, RL = 3k, CL = 1000pF 25 Full Normal Operation, RL = 3k, CL = 1000pF 25 Full VCC = 3V to 3.6V, RL = 3k to 7k, Measured From 3V to -3V or -3V to 3V CL = 150pF to 1000pF 25 Full CL = 150pF to 2500pF 25 Full Transition Region Slew Rate ISL4245E ESD PERFORMANCE RS-232 Pins (TOUT, RIN) Human Body Model IEC6100-4-2 Air Gap Discharge IEC6100-4-2 Contact Discharge All Other Pins NOTES: 4. ISL4238E inputs utilize a positive feedback resistor. The input current is negligible when the input is at either supply rail. 5. An "edge" is defined as a transition through the transmitter or receiver input thresholds. 6. Skew is measured at the receiver input switching points (1.4V). 7. Skew is measured at the transmitter zero crossing points. Human Body Model 25 25 25 25 15 15 8 3 kV kV kV kV VCC = 3V to 3.6V, RL = 3k to 7k, Measured From 3V to -3V or -3V to 3V, CL = 150pF to 1000pF 25 Full MIN 6 6 4 4 24 24 TYP 200 200 350 400 25 35 2.5 2.7 11 10 9 8 40 35 MAX 350 400 500 600 40 50 4 4 30 30 30 30 150 150 UNITS ns ns ns ns s s s s V/s V/s V/s V/s V/s V/s
PARAMETER Receiver Output Enable Time
Detailed Description
These interface ICs operate from a single +2.7V to +5.5V supply, guarantee a 250kbps (ISL4238E/44E) / 1Mbps (ISL4245E) minimum data rate, require only four small external 0.1F capacitors, feature low power consumption, and meet all ElA RS-232C and V.28 specifications. The circuit is divided into three sections: The charge pump, the transmitters, and the receivers.
Transmitters
The transmitters are proprietary, low dropout, inverting drivers that translate TTL/CMOS inputs to EIA/TIA-232 output levels. Coupled with the on-chip 5.5V supplies, these transmitters deliver true RS-232 levels over a wide range of single supply system voltages. Transmitter outputs disable and assume a high impedance state when the device enters the powerdown mode (see Table 2). These outputs may be driven to 12V when disabled. The ISL4238E/44E guarantee a 250kbps data rate for full load conditions (3k and 1000pF), VCC 3.0V, with one transmitter operating at full speed. Under more typical conditions of VCC 3.3V, RL = 3k, and CL = 250pF, one transmitter easily operates at 1Mbps. The ISL4245E guarantees a 1Mbps data rate for full load conditions (3k and 250pF), VCC 3.0V, with one transmitter operating at full speed. Under more typical conditions of VCC 3.3V, RL = 3k, and CL = 250pF, one transmitter easily operates at 1.4Mbps.
Charge-Pump
Intersil's new RS-232 family utilizes regulated on-chip dual charge pumps as voltage doublers, and voltage inverters to generate 5.5V transmitter supplies from a VCC supply as low as 3.0V. This allows these devices to maintain RS-232 compliant output levels over the 10% tolerance range of 3.3V powered systems. The efficient on-chip power supplies require only four small, external 0.1F capacitors for the voltage doubler and inverter functions. The charge pumps operate discontinuously (i.e., they turn off as soon as the V+ and V- supplies are pumped up to the nominal values), resulting in significant power savings.
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ISL4238E, ISL4244E, ISL4245E
TABLE 2. POWERDOWN LOGIC TRUTH TABLE RCVR OR XMTR EDGE WITHIN 30 SEC? NO NO YES YES NO NO X X RS-232 LEVEL PRESENT AT RECEIVER INPUT? NO YES NO YES NO YES NO YES
ROUTB FORCEOFF FORCEON TRANSMITTER RECEIVER INPUT INPUT OUTPUTS OUTPUTS OUTPUTS H H H H H H L L H H L L L L X X Active Active Active Active High-Z High-Z High-Z High-Z Active Active Active Active Active Active High-Z High-Z Active Active Active Active Active Active Active Active
INVALID OUTPUT L H L H L H L H
MODE OF OPERATION Normal Operation (Enhanced Auto Powerdown Disabled) Normal Operation (Enhanced Auto Powerdown Enabled) Powerdown Due to Enhanced Auto Powerdown Logic Manual Powerdown
INVALID DRIVING FORCEON AND FORCEOFF (EMULATES AUTOMATIC POWERDOWN) X X NOTE: 8. Input is connected to INVALID Output. NOTE 8 NOTE 8 NOTE 8 NOTE 8 Active High-Z Active High-Z Active Active YES NO H L Normal Operation Forced Auto Powerdown
Transmitter inputs on the ISL424XE float if left unconnected, and may cause ICC increases. Connect unused inputs to GND for the best performance. ISL4238E transmitter inputs incorporate an active positive feedback resistor that maintains the last input state in the absence of a forcing signal, so unused transmitter inputs may be left unconnected.
prevent current flow through the peripheral's protection diodes (see Figures 2 and 3). This renders them useless for wake up functions, but the corresponding monitor receiver can be dedicated to this task as shown in Figure 3.
VCC VCC CURRENT FLOW VOUT = VCC Rx POWERED DOWN UART Tx GND SHDN = GND OLD RS-232 CHIP
VCC
Receivers
ISL4238E/4XE devices contain standard inverting receivers which can tristate via the FORCEOFF control line. Additionally, they include a noninverting (monitor) receiver (denoted by the ROUTB label) that is always active, regardless of the state of any control lines. Both receiver types convert RS-232 signals to CMOS output levels and accept inputs up to 25V while presenting the required 3k to 7k input impedance (see Figure 1) even if the power is off (VCC = 0V). The receivers' Schmitt trigger input stage uses hysteresis to increase noise immunity and decrease errors due to slow input signal transitions.
VCC RXIN -25V VRIN +25V GND 5k RXOUT GND VROUT VCC
FIGURE 2. POWER DRAIN THROUGH POWERED DOWN PERIPHERAL
Low Power Operation
These 3V devices require a nominal supply current of 0.3mA, even at VCC = 5.5V, during normal operation (not in powerdown mode). This is considerably less than the 5mA to 11mA current required by comparable 5V RS-232 devices, allowing users to reduce system power simply by switching to this new family.
FIGURE 1. INVERTING RECEIVER CONNECTIONS
The ISL4238E/4XE inverting receivers disable during forced (manual) powerdown, but not during automatic powerdown (see Table 2). Conversely, the monitor receiver remains active even during manual powerdown making it extremely useful for Ring Indicator monitoring. Standard receivers driving powered down peripherals must be disabled to 9
ISL4238E, ISL4244E, ISL4245E
VCC PWR MGT LOGIC ISL4238E/4XE FORCEOFF FORCEON
TRANSITION DETECTOR TO WAKE-UP LOGIC VCC ROUTB RX POWERED DOWN UART VOUT = HI-Z ROUT TX T1IN T1OUT FORCEOFF = GND RIN
INVALID ISL4238E/4XE
I/O UART CPU
FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN
Powerdown Functionality
The already low current requirement drops significantly when the device enters powerdown mode. In powerdown, supply current drops to 10nA, because the on-chip charge pump turns off (V+ collapses to VCC, V- collapses to GND), and the transmitter outputs tristate. Inverting receiver outputs disable only in manual powerdown; refer to Table 2 for details. This micro-power mode makes these devices ideal for battery powered and portable applications.
FIGURE 4. CONNECTIONS FOR MANUAL POWERDOWN WHEN NO VALID RECEIVER SIGNALS ARE PRESENT
Software Controlled (Manual) Powerdown
These devices allow the user to force the IC into the low power, standby state, and utilize a two pin approach where the FORCEON and FORCEOFF inputs determine the IC's mode. For always enabled operation, FORCEON and FORCEOFF are both strapped high. To switch between active and powerdown modes, under logic or software control, only the FORCEOFF input need be driven. The FORCEON state isn't critical, as FORCEOFF dominates over FORCEON. Nevertheless, if strictly manual control over powerdown is desired, the user must strap FORCEON high to disable the enhanced automatic powerdown circuitry. ISL4238E/4XE inverting (standard) receiver outputs also disable when the device is in manual powerdown, thereby eliminating the possible current path through a shutdown peripheral's input protection diode (see Figures 2 and 3). Connecting FORCEOFF and FORCEON together disables the enhanced automatic powerdown feature, enabling them to function as a manual SHUTDOWN input (see Figure 4). With any of the above control schemes, the time required to exit powerdown, and resume transmission is only 100s.
When using both manual and enhanced automatic powerdown (FORCEON = 0), the ISL4238E/4XE won't power up from manual powerdown until both FORCEOFF and FORCEON are driven high, or until a transition occurs on a receiver or transmitter input. Figure 5 illustrates a circuit for ensuring that the ISL4238E/4XE powers up as soon as FORCEOFF switches high. The rising edge of the Master Powerdown signal forces the device to power up, and the ISL4238E/4XE returns to enhanced automatic powerdown mode an RC time constant after this rising edge. The time constant isn't critical, because the ISL4238E/4XE remains powered up for 30 seconds after the FORCEON falling edge, even if there are no signal transitions. This gives slow-towake systems (e.g., a mouse) plenty of time to start transmitting, and as long as it starts transmitting within 30 seconds both systems remain enabled.
POWER MANAGEMENT UNIT MASTER POWERDOWN LINE 0.1F 1M
FORCEOFF
FORCEON
ISL4238E/4XE
FIGURE 5. CIRCUIT TO ENSURE IMMEDIATE POWER UP WHEN EXITING FORCED POWERDOWN
INVALID Output
The INVALID output always indicates (see Table 2) whether or not 30s have elapsed with invalid RS-232 signals (see Figures 6 and 9) persisting on all of the receiver inputs, giving the user an easy way to determine when the interface block should power down. Invalid receiver levels occur whenever the driving peripheral's outputs are shut off (powered down) or when the RS-232 interface cable is disconnected. In the case of a disconnected interface cable where all the receiver inputs are floating (but pulled to GND
10
ISL4238E, ISL4244E, ISL4245E
by the internal receiver pull down resistors), the INVALID logic detects the invalid levels and drives the output low. The power management logic then uses this indicator to power down the interface block. Reconnecting the cable restores valid levels at the receiver inputs, INVALID switches high, and the power management logic wakes up the interface block. INVALID can also be used to indicate the DTR or RING INDICATOR signal, as long as the other receiver inputs are floating, or driven to GND (as in the case of a powered down driver). INVALID switches high 1s after detecting a valid RS-232 level on a receiver input. INVALID operates in all modes (forced or automatic powerdown, or forced on), so it is also useful for systems employing manual powerdown circuitry.
VALID RS-232 LEVEL - INVALID = 1 2.7V INDETERMINATE FORCEOFF T_IN EDGE DETECT S 30sec TIMER R_IN EDGE DETECT R AUTOPWDN
FORCEON
FIGURE 7. ENHANCED AUTOMATIC POWERDOWN LOGIC
on the state of the ISL4238E/4XE (see the next sections for methods of utilizing INVALID to power down the device). The time to recover from automatic powerdown mode is typically 100s.
Emulating Standard Automatic Powerdown
If enhanced automatic powerdown isn't desired, the user can implement the standard automatic powerdown feature (mimics the function on the ISL4243E) by connecting the INVALID output to the FORCEON and FORCEOFF inputs, as shown in Figure 8. After 30s of invalid receiver levels, INVALID switches low and drives the ISL4238E/4XE into a forced powerdown condition. INVALID switches high as soon as a receiver input senses a valid RS-232 level, forcing the ISL4238E/4XE to power on. See the "INVALID DRIVING FORCEON AND FORCEOFF" section of Table 2 for an operational summary. This operational mode is perfect for handheld devices that communicate with another computer via a detachable cable. Detaching the cable allows the internal receiver pull-down resistors to pull the inputs to GND (an invalid RS-232 level), causing the 30s timer to time-out and drive the IC into powerdown. Reconnecting the cable restores valid levels, causing the IC to power back up.
FORCEON INVALID FORCEOFF
0.3V INVALID LEVEL - INVALID = 0 -0.3V INDETERMINATE
-2.7V VALID RS-232 LEVEL - INVALID = 1
FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS
Enhanced Automatic Powerdown
Even greater power savings is available by using these devices which feature an enhanced automatic powerdown function. When the enhanced powerdown logic determines that no transitions have occurred on any of the transmitter nor receiver inputs for 30 seconds, the charge pump and transmitters powerdown, thereby reducing supply current to 10nA. The ISL4238E/4XE automatically powers back up whenever it detects a transition on one of these inputs. This automatic powerdown feature provides additional system power savings without changes to the existing operating system. Enhanced automatic powerdown operates when the FORCEON input is low, and the FORCEOFF input is high. Tying FORCEON high disables automatic powerdown, but manual powerdown is always available via the overriding FORCEOFF input. Table 2 summarizes the enhanced automatic powerdown functionality. Figure 7 illustrates the enhanced powerdown control logic. Note that once the ISL4238E/4XE enters powerdown (manually or automatically), the 30 second timer remains timed out (set), keeping the ISL4238E/4XE powered down until FORCEON transitions high, or until a transition occurs on a receiver or transmitter input. The INVALID output signal switches low to indicate that invalid levels have persisted on all of the receiver inputs for more than 30s (see Figure 9), but this has no direct effect 11
ISL4238E/4XE
I/O UART
CPU
FIGURE 8. CONNECTIONS FOR AUTOMATIC POWERDOWN WHEN NO VALID RECEIVER SIGNALS ARE PRESENT
Hybrid Automatic Powerdown Options
For devices which communicate only through a detachable cable, connecting INVALID to FORCEOFF (with FORCEON = 0) may be a desirable configuration. While the
ISL4238E, ISL4244E, ISL4245E
RECEIVER INPUTS TRANSMITTER INPUTS TRANSMITTER OUTPUTS tINVH INVALID OUTPUT OUTPUT V+ tINVL tAUTOPWDN tWU tAUTOPWDN tWU
INVALID } REGION
VCC 0 V-
FIGURE 9. ENHANCED AUTOMATIC POWERDOWN AND INVALID TIMING DIAGRAMS
cable is attached INVALID and FORCEOFF remain high, so the enhanced automatic powerdown logic powers down the RS-232 device whenever there is 30 seconds of inactivity on the receiver and transmitter inputs. Detaching the cable allows the receiver inputs to drop to an invalid level (GND), so INVALID switches low and forces the RS-232 device to power down. The ISL4238E/4XE remains powered down until the cable is reconnected (INVALID = FORCEOFF = 1) and a transition occurs on a receiver or transmitter input (see Figure 7). For immediate power up when the cable is reattached, connect FORCEON to FORCEOFF through a network similar to that shown in Figure 5.
When using minimum required capacitor values, make sure that capacitor values do not degrade excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor's equivalent series resistance (ESR) usually rises at low temperatures and it influences the amount of ripple on V+ and V-.
Power Supply Decoupling
In most circumstances a 0.1F bypass capacitor is adequate. In applications that are particularly sensitive to power supply noise, decouple VCC to ground with a capacitor of the same value as the charge-pump capacitor C1. Connect the bypass capacitor as close as possible to the IC.
Capacitor Selection
The ISL4238E charge pumps require 0.1F, or greater, capacitors for 3.3V (5% tolerance) operation. For other supply voltages refer to Table 3 for capacitor values. Do not use values smaller than those listed in Table 3.
TABLE 3. REQUIRED CAPACITOR VALUES (ISL4238E) VCC (V) 3.0 to 3.6 (3.3V 10%) 3.15 to 3.6 (3.3V 5%) 4.5 to 5.5 3.0 to 5.5 C1 (F) 0.22 0.1 0.047 0.22 C2, C3, C4 (F) 0.22 0.1 0.33 1
Transmitter Outputs when Exiting Powerdown
Figure 10 shows the response of two transmitter outputs when exiting powerdown mode. As they activate, the two transmitter outputs properly go to opposite RS-232 levels, with no glitching, ringing, nor undesirable transients. Each transmitter is loaded with 3k in parallel with 2500pF. Note that the transmitters enable only when the magnitude of the supplies exceed approximately 3V.
Operation Down to 2.7V
ISL4238E/4XE transmitter outputs meet RS-562 levels (3.7V), at the full data rate, with VCC as low as 2.7V. RS-562 levels typically ensure interoperability with RS-232 devices.
The ISL4244E/45E charge pumps require 0.1F capacitors for proper operation. Increasing the capacitor values (by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consumption. C2, C3, and C4 can be increased without increasing C1's value, however, do not increase C1 without also increasing C2, C3, and C4 to maintain the proper ratios (C1 to the other capacitors).
12
ISL4238E, ISL4244E, ISL4245E
for a single transmitter driving 250pF and an RS-232 load at 1Mbps. The static transmitters were also loaded with an RS-232 receiver.
VCC 0.1F +
5V/DIV
FORCEOFF T1
2V/DIV + C1 C1T2 VCC = +3.3V C1 - C4 = 0.1F TIME (20s/DIV.) C2 C2TIN ROUT FORCEON VCC C1+
VCC
V+
+ C3
ISL4238E/4XE + C2+ VC4 +
TOUT RIN 5k CL
FIGURE 10. TRANSMITTER OUTPUTS WHEN EXITING POWERDOWN
Mouse Driveability
The ISL424XE are specifically designed to power a serial mouse while operating from low voltage supplies. Figure 11 shows the transmitter output voltages under increasing load current. The on-chip switching regulator ensures the transmitters will supply at least 5V during worst case conditions (15mA for paralleled V+ transmitters, 7.3mA for single V- transmitter).
6 TRANSMITTER OUTPUT VOLTAGE (V) 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0 1 2 3 4 5 6 7 8 9 10 LOAD CURRENT PER TRANSMITTER (mA) VCC T3 T2 ISL424XE VOUT VOUT R1OUT VCC = 3.0V T1 VOUT+ T1OUT VOUT+
FORCEOFF
FIGURE 12. TRANSMITTER LOOPBACK TEST CIRCUIT
5V/DIV. T1IN
VCC = +3.3V C1 - C4 = 0.1F 5s/DIV.
FIGURE 13. ISL4238E/44E LOOPBACK TEST AT 120kbps
FIGURE 11. TRANSMITTER OUTPUT VOLTAGE vs LOAD CURRENT (PER TRANSMITTER, i.e., DOUBLE CURRENT AXIS FOR TOTAL VOUT+ CURRENT)
5V/DIV. T1IN
High Data Rates
The ISL4238E/4XE maintain the RS-232 5V minimum transmitter output voltages even at high data rates. Figure 12 details a transmitter loopback test circuit, and Figure 13 illustrates the ISL4238E/44E loopback test result at 120kbps. For this test, all transmitters were simultaneously driving RS-232 loads in parallel with 1000pF, at 120kbps. Figure 14 shows the ISL4238E/44E loopback results for a single transmitter driving 1000pF and an RS-232 load at 250kbps. Figure 15 illustrates the ISL4245E loopback test result at 250kbps. For this test, all transmitters were simultaneously driving RS-232 loads in parallel with 1000pF, at 250kbps. Figure 16 shows the ISL4245E loopback results 13
T1OUT
R1OUT VCC = +3.3V C1 - C4 = 0.1F 2s/DIV.
FIGURE 14. ISL4238E/44E LOOPBACK TEST AT 250kbps (CL = 1000pF)
ISL4238E, ISL4244E, ISL4245E
5V/DIV. T1IN
TABLE 4. LOGIC FAMILY COMPATIBILITY WITH VARIOUS SUPPLY VOLTAGES SYSTEM VCC POWER-SUPPLY SUPPLY VOLTAGE VOLTAGE (V) (V) 3.3 5 3.3 5 3.3
COMPATIBILITY Compatible with all CMOS families. Compatible with all TTL and CMOS logic families. Compatible with ACT and HCT CMOS, and with TTL. ISL4238E/4XE outputs are incompatible with AC, HC, and CD4000 CMOS inputs.
T1OUT
R1OUT VCC = +3.3V C1 - C4 = 0.1F 2s/DIV.
5
FIGURE 15. ISL4245E LOOPBACK TEST AT 250kbps
15kV ESD Protection
5V/DIV. T1IN
T1OUT
R1OUT VCC = +3.3V C1 - C4 = 0.1F 0.5s/DIV.
All pins on ISL4238E/4XE devices include ESD protection structures, but the RS-232 pins (transmitter outputs and receiver inputs) incorporate advanced structures which allow them to survive ESD events up to 15kV. The RS-232 pins are particularly vulnerable to ESD damage because they typically connect to an exposed port on the exterior of the finished product. Simply touching the port pins, or connecting a cable, can cause an ESD event that might destroy unprotected ICs. These new ESD structures protect the device whether or not it is powered up, protect without allowing any latchup mechanism to activate, and don't interfere with RS-232 signals as large as 25V.
Human Body Model (HBM) Testing
As the name implies, this test method emulates the ESD event delivered to an IC during human handling. The tester delivers the charge through a 1.5k current limiting resistor, making the test less severe than the IEC6100 test which utilizes a 330 limiting resistor. The HBM method determines an ICs ability to withstand the ESD transients typically present during handling and manufacturing. Due to the random nature of these events, each pin is tested with respect to all other pins. The RS-232 pins on "E" family devices can withstand HBM ESD events to 15kV.
FIGURE 16. ISL4245E LOOPBACK TEST AT 1Mbps (CL = 250pF)
Interconnection with 3V and 5V Logic
The ISL4238E/4XE directly interface with 5V CMOS and TTL logic families. Nevertheless, with the ISL4238E/4XE at 3.3V, and the logic supply at 5V, AC, HC, and CD4000 outputs can drive ISL4238E/4XE inputs, but ISL4238E/4XE outputs do not reach the minimum VIH for these logic families. See Table 4 for more information.
IEC6100-4-2 Testing
The IEC6100 test method applies to finished equipment, rather than to an individual IC. Therefore, the pins most likely to suffer an ESD event are those that are exposed to the outside world (the RS-232 pins in this case), and the IC is tested in its typical application configuration (power applied) rather than testing each pin-to-pin combination. The lower current limiting resistor coupled with the larger charge storage capacitor yields a test that is much more severe than the HBM test. The extra ESD protection built into this device's RS-232 pins allows the design of equipment meeting level 4 criteria without the need for additional board level protection on the RS-232 port.
14
ISL4238E, ISL4244E, ISL4245E
AIR-GAP DISCHARGE TEST METHOD For this test method, a charged probe tip moves toward the IC pin until the voltage arcs to it. The current waveform delivered to the IC pin depends on approach speed, humidity, temperature, etc., so it is difficult to obtain repeatable results. The "E" device RS-232 pins withstand 15kV air-gap discharges. CONTACT DISCHARGE TEST METHOD During the contact discharge test, the probe contacts the tested pin before the probe tip is energized, thereby eliminating the variables associated with the air-gap discharge. The result is a more repeatable and predictable test, but equipment limits prevent testing devices at voltages higher than 8kV. All "E" family devices survive 8kV contact discharges on the RS-232 pins.
Typical Performance Curves
6 TRANSMITTER OUTPUT VOLTAGE (V)
VCC = 3.3V, TA = 25oC
6 TRANSMITTER OUTPUT VOLTAGE (V) VOUT+ VOUT+ 4 2 1 TRANSMITTER AT 250kbps OTHER TRANSMITTERS AT 30kbps 0 -2 -4 -6
4 2 1 TRANSMITTER AT 250kbps OTHER TRANSMITTERS AT 30kbps 0 -2 -4 -6 VOUT -
VOUT -
0
1000
2000
3000
4000
5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
FIGURE 17. ISL4238E TRANSMITTER OUTPUT VOLTAGE vs LOAD CAPACITANCE
6 TRANSMITTER OUTPUT VOLTAGE (V) VOUT+ 4
FIGURE 18. ISL4244E TRANSMITTER OUTPUT VOLTAGE vs LOAD CAPACITANCE
55 1 TRANSMITTER AT INDICATED RATE 50 SUPPLY CURRENT (mA) 45 40 35 30 25 20 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) 20kbps 120kbps 250kbps
2 1 TRANSMITTER AT 1Mbps OTHER TRANSMITTERS AT 30kbps 0 -2 -4 -6 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF)
VOUT -
FIGURE 19. ISL4245E TRANSMITTER OUTPUT VOLTAGE vs LOAD CAPACITANCE
FIGURE 20. ISL4238E SUPPLY CURRENT vs LOAD CAPACITANCE WHEN TRANSMITTING DATA
15
ISL4238E, ISL4244E, ISL4245E Typical Performance Curves
45 1 TRANSMITTER AT INDICATED RATE 40 SUPPLY CURRENT (mA) 250kbps SUPPLY CURRENT (mA) 35 30 120kbps 25 20 20kbps 15 10 0 1000 2000 3000 4000 5000 10 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) 70 60 50 40 30 20 250kbps 80
VCC = 3.3V, TA = 25oC (Continued)
90 1 TRANSMITTER AT INDICATED RATE 1Mbps
120kbps
FIGURE 21. ISL4244E SUPPLY CURRENT vs LOAD CAPACITANCE WHEN TRANSMITTING DATA
25
FIGURE 22. ISL4245E SUPPLY CURRENT vs LOAD CAPACITANCE WHEN TRANSMITTING DATA
110
90 20 SLEW RATE (V/s) SLEW RATE (V/s) -SLEW +SLEW 70
15 +SLEW 10
50 -SLEW 30
10 5 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) 0 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF)
FIGURE 23. ISL4238E/44E SLEW RATE vs LOAD CAPACITANCE
3.5 NO LOAD ALL OUTPUTS STATIC 3.0 SUPPLY CURRENT (mA) 2.5 2.0 1.5 1.0 0.5 0 2.5
FIGURE 24. ISL4245E SLEW RATE vs LOAD CAPACITANCE
Die Characteristics
SUBSTRATE POTENTIAL (POWERED UP) GND TRANSISTOR COUNT ISL4238E: 1235 ISL4244E: 1109 ISL4245E: 1109 PROCESS Si Gate CMOS
3.0
3.5
4.0
4.5
5.0
5.5
6.0
SUPPLY VOLTAGE (V)
FIGURE 25. SUPPLY CURRENT vs SUPPLY VOLTAGE
16
ISL4238E, ISL4244E, ISL4245E Quad Flat No-Lead Plastic Package (QFN) Micro Lead Frame Plastic Package (MLFP)
L32.5x5
32 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE (COMPLIANT TO JEDEC MO-220VHHD-2 ISSUE C MILLIMETERS SYMBOL A A1 A2 A3 b D D1 D2 E E1 E2 e k L L1 N Nd Ne P 8 0.25 0.30 2.95 2.95 0.18 MIN 0.80 NOMINAL 0.90 0.20 REF 0.23 5.00 BSC 4.75 BSC 3.10 5.00 BSC 4.75 BSC 3.10 0.50 BSC 0.40 32 8 8 0.60 12 0.50 0.15 3.25 3.25 0.30 MAX 1.00 0.05 1.00 NOTES 9 9 5,8 9 7,8 9 7,8 8 10 2 3 3 9 9 Rev. 1 10/02 NOTES: 1. Dimensioning and tolerancing conform to ASME Y14.5-1994. 2. N is the number of terminals. 3. Nd and Ne refer to the number of terminals on each D and E. 4. All dimensions are in millimeters. Angles are in degrees. 5. Dimension b applies to the metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip. 6. The configuration of the pin #1 identifier is optional, but must be located within the zone indicated. The pin #1 identifier may be either a mold or mark feature. 7. Dimensions D2 and E2 are for the exposed pads which provide improved electrical and thermal performance. 8. Nominal dimensions are provided to assist with PCB Land Pattern Design efforts, see Intersil Technical Brief TB389. 9. Features and dimensions A2, A3, D1, E1, P & are present when Anvil singulation method is used and not present for saw singulation. 10. Depending on the method of lead termination at the edge of the package, a maximum 0.15mm pull back (L1) maybe present. L minus L1 to be equal to or greater than 0.3mm.
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation's quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com 17

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