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Part: A2557KEB
Category:
Description: Protected Quad Low-side Driver With Fault Detection And Sleep Mode
Company: Allegro Micro Systems, Inc.
Datasheet: Download A2557KEB datasheet File size : 192 kB
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Datasheet text preview:
2557
A2557xLB
OUT1 K OUT2 GROUND GROUND OUT3 FAULT OUT4 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 IN 1 IN 2 ENABLE GROUND GROUND V CC IN 3 IN 4
PROTECTED QUAD LOW-SIDE DRIVER WITH FAULT DETECTION & SLEEP MODE
The A2557xB, A2557xEB, and A2557xLB have been specifically designed to provide cost-effective solutions to relay-driving applications with up to 300 mA drive current per channel. They may also be used for driving incandescent lamps in applications where turn-on time is not a concern. Each of the four outputs will sink 300 mA in the on state. The outputs have a minimum breakdown voltage of 60 V and a sustaining voltage of 40 V. A low-power Sleep Mode is activated with either ENABLE low or all inputs low. In this mode, the supply current drops to below 100 µA. Over-current protection for each channel has been designed into these devices and is activated at a nominal 500 mA. It protects each output from short circuits with supply voltages up to 32 V. When an output experiences a short circuit, the output current is limited at the 500 mA current clamp. In addition, foldback circuitry decreases the current limit if an excessive voltage is present across the output and assists in keeping the device within its SOA (safe operating area). An exclusive-OR circuit compares the input and output state of each driver. If either a short or open load condition is detected, a single FAULT output is turned on (active low). Similar devices, for operation to 1.3 A, are available as the UDx2547B/EB. Continuous or multiple overload conditions causing the channel temperature to reach approximately 165°C will result in an additional linear decrease in the output current of the affected driver. If the fault condition is corrected, the output stage will return to its normal saturated condition. The first character of the part number suffix determines the device operating temperature range. Suffix `S-' is the standard -20°C to +85°C; suffix `E-' is -40°C to +85°C; suffix `K-' is for the industrial temperature range of -40°C to +125°C. Package suffix `-B' devices are 16-pin power DIPs; suffix `-EB' devices are 28-lead power PLCCs; and suffix `-LB' are 16lead power wide-body SOICs for surface-mount applications. All packages are of batwing construction to provide for maximum package power dissipation.
Data Sheet 29317.16E
Dwg. PP-017-4
Note that the A2557xB (DIP) and the A2557xLB (SOIC) are electrically identical and share a common terminal number assignment.
ABSOLUTE MAXIMUM RATINGS
Output Voltage, VO ...... 60 V Over-Current Protected Output Voltage, VO ..... 32 V Output Current, IO ....... 500 mA* FAULT Output Voltage, VFLT .... 60 V Logic Supply Voltage, VCC ........ 7.0 V Input Voltage, VI or VOE ............ 7.0 V Package Power Dissipation, PD .......... See Graph Operating Temperature Range, TA Suffix `S-' .... -20°C to +85°C Suffix `E-' .... -40°C to +85°C Suffix `K-' .......... -40°C to +125°C Junction Temperature, TJ ..... +150°C* Storage Temperature Range, TS ......... -55°C to +150°C
*Outputs are current limited at approximately 500 mA per driver and junction temperature limited if higher current is attempted.
FEATURES I 300 mA Output Current per Channel I Independent Over-Current Protection &Thermal Limiting for Each Driver I Output Voltage to 60 V I Output SOA Protection I Fault-Detection Circuitry for Open or Shorted Load I Low Quiescent Current Sleep Mode I Integral Output Flyback/Clamp Diodes I TTL- and 5 V CMOS-Compatible Inputs
Complete part number includes a suffix to identify operating temperature range (E-, K-, or S-) and package type (-B, -EB, or -LB). Always order by complete part number, e.g., A2557KLB .
2557 PROTECTED QUAD DRIVER WITH FAULT DETECTION & SLEEP MODE
FUNCTIONAL BLOCK DIAGRAM
FAULT ENABLE SLEEP CONTROL
60 µA K
COMMON CONTROL ONE OF FOUR DRIVERS V CC
+
2.5 V OUTN
IN N THERMAL LIMIT CURRENT LIMIT
30 µA
<<1
Dwg. FP-007-2
A2557xEB
NO CONNECTION
ENABLE
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
5
OUT2
OUT1
IN 1
K
IN 2
28
27
26
4
2
3
1
R
4
SUFFIX 'EB', R JA = 36°C/W
JT
= 6°C/W
NC GROUND 5 6 7 8 9 10 GROUND 11 NC VCC 25 24 23 22 21 20 19 GROUND GROUND
3
SUFFIX 'B', R JA = 43°C/W
2
1
15
12
13
14
16
17
18
SUFFIX 'LB', R JA = 63°C/W
0 25 50 75 100 TEMPERATURE IN °C 125 150
NO CONNECTION
FAULT
OUT 4
OUT 3
IN 4
IN 3
SUPPLY
Dwg. GP-004-2A
Dwg. PP-019-2
2
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 1998, 2000, Allegro MicroSystems, Inc.
2557 PROTECTED QUAD DRIVER WITH FAULT DETECTION & SLEEP MODE
ELECTRICAL CHARACTERISTICS over operating temperature range, VCC = 4.75 V to 5.25 V
Characteristic
Output Leakage Current*
Symbol
IC E X
Test Conditions
VO = 60 V, VI = 0.8 V, VOE = 2.0 V VO = 60 V, VI = 2.0 V, VOE = 0.8 V
Min.
-- -- 40 -- -- -- 2.0 -- -- -- -- -- 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Limits Typ. Max.
30 <1.0 -- 65 180 500 -- -- -- -- 4.0 <1.0 60 0.1 1.2 1.5 -- 0.6 3.0 1.3 2.0 1.4 0.075 12 18 24 30 165 100 100 -- 200 300 -- -- 0.8 10 -10 15 2.0 80 0.4 1.7 2.1 50 10 -- 10 10 10 0.1 20 30 40 50 --
Units
µA µA V mV mV mA V V µA µA µA µA µA V V V µA µs µs µs µs µs mA mA mA mA mA °C
Output Sustaining Voltage Output Saturation Voltage
VO ( S U S ) VO ( S A T )
IO = 100 mA, VI = VOE = 0.8 V, VCC = Open IO = 100 mA IO = 300 mA
Over-Current Limit Input Voltage
IO M V IH VIL
5 ms PulseTest, VO = 5.0 V INn or ENABLE INn or ENABLE INn or ENABLE, VIH = 2.0 V INn or ENABLE, VIL = 0.8 V VFLT = 60 V VFLT = 5 V
Input Current
II H I IL
Fault Output Leakage Current
IFLT
Fault Output Current Fault Output Saturation Voltage Clamp Diode Forward Voltage
IF L T VF L T ( S A T ) VF
VFLT = 5 V, Driver Output Open, VI = 0.8 V, VOE = 2.0 V IFLT = 30 µA IF = 500 mA IF = 750 mA
Clamp Diode Leakage Current Turn-On Delay
IR tP H L
VR = 60 V IO = 300 mA, 50% VI to 50% VO From Sleep, IO = 300 mA, 50% VI to 50% VO IO = 300 mA, 50% VOE to 50% VO
Turn-Off Delay
tP L H
IO = 300 mA, 50% VI to 50% VO IO = 300 mA, 50% VOE to 50% VO
Total Supply Current
I CC
All Outputs Off Any One Output On Two Outputs On Three Outputs On All Outputs On
Thermal Limit
TJ
Typical Data is at TA = +25°C and VCC = 5 V and is for design information only. Negative current is defined as coming out of (sourcing) the specified terminal. As used here, -100 is defined as greater than +10 (absolute magnitude convention) and the minimum is implicitly zero. * Measurement includes output fault-sensing pull-down current.
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3
2557 PROTECTED QUAD DRIVER WITH FAULT DETECTION & SLEEP MODE
TYPICAL OPERATING CHARACTERISTICS
600 TA = +25°C VCC = 5 V 500
0.2
TA
=
C 5° 12
5°C =2
TA
OUTPUT CURRENT LIMIT IN MILLIAMPERES
400
Dwg. GP-064
OUTPUT SATURATION VOLTAGE IN VOLTS
0.3
VCC = 5 V
TA
0.1
°C 40 =-
400
300
0 0 100 200 300
0
10
20
30
40
Dwg. GP-065
OUTPUT CURRENT IN MILLIAMPERES
OUTPUT VOLTAGE IN VOLTS
6
IN SWITCHING (FROM SLEEP)
TURN-OFF DELAY IN MICROSECONDS
4
TURN-ON DELAY IN MICROSECONDS
TA = +25°C VCC = 5 V
3
TA = +25°C VCC = 5 V 2
IN S WIT CH ING
ENABLE SWITCHING
2
ENA
BLE
SW
ITC
HIN
1
G
IN SWITCHING (AWAKE)
0 0 100 200 300 400
Dwg. GP-066
0 0 100 200 300 400
Dwg. GP-066-1
OUTPUT CURRENT IN MILLIAMPERES
OUTPUT CURRENT IN MILLIAMPERES
4
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
2557 PROTECTED QUAD DRIVER WITH FAULT DETECTION & SLEEP MODE
CIRCUIT DESCRIPTION AND APPLICATION
The A2557 low-current quad power drivers provide the same protected output driver function as (and are pin compatible with) the UDx2543/49/59 devices, combined with a fault diagnostic scheme similar to the UDx2547, plus an automatic low-current Sleep-Mode function. These devices monitor their outputs for fault (open or shorted) conditions. For each channel the input and output levels are compared. If these are different from the expected levels then a fault condition is flagged by pulling the common FAULT output low. Status Normal Load Sleep Mode Over-Current or Short to Supply Open Load or Short to Ground INN H L X All L H L ENABLE H H L X H H OUTN L H H H R L H FAULT H H H H L L L · if the power dissipation in the output device increases the local junction temperature above 165°C (nominal), so as to limit the power dissipation (and hence the local junction temperature). As each channel has its own thermal limit circuitry this provides some independence between the output channels, i.e., one channel can be operating in thermally reduced current limit, while the others can provide full drive capability. · as a function of the output voltage. Full current limit of 500 mA (nominal) is available up to approximately VO = 8 V; above this the limit is reduced linearly to about 350 mA at VO = 32 V. This helps to improve SOA by immediately reducing the peak power pulse into a shorted load at high VO. A logic low at the ENABLE input causes all outputs to be switched off regardless of the state of the IN terminals. In addition, the device is put into a low quiescent current `sleep' mode, reducing ICC below 100 µA. If ENABLE is taken high and any of the inputs go high, the circuit will `auto-wake-up'. However, if the device is enabled, but all inputs stay low, then the circuit remains in `sleep' mode. All outputs have internal flyback diodes, with a commoncathode connection at the K terminal. Incandescent lamp driver High incandescent lamp turn-on (in-rush currents) can contribute to poor lamp reliability and destroy semiconductor lamp drivers. When an incandescent lamp is initially turned on, the cold filament is at minimum resistance and would normally allow a 10x to 12x in-rush current. Warming (parallel) or current-limiting (series) resistors protect both driver and lamp but use significant power either when the lamp is off or when the lamp is on, respectively. Lamps with steady-state current ratings up to 300 mA can be driven without the need for warming or current-limiting resistors, if lamp turn-on time is not a concern (10s of ms). With these drivers, during turn-on, the high in-rush current is sensed by the internal sense resistor, drive current to the output stage is reduced, and the output operates in a linear mode with the load current limited to approximately 500 mA. During lamp warmup, the filament resistance increases to its maximum value, the output driver goes into saturation and applies maximum rated voltage to the lamp.
Thermal Fault H H R = Linear drive, current limited.
The FAULT output is operational only if ENABLE is high. The output state is detected by monitoring the OUTn terminal using a comparator whose threshold is typically 2.5 V. In order to detect open-circuit outputs, a 30 µA current sink pulls the output below the comparator threshold. To ensure correct fault operation, a minimum load of approximately 1 mA is required. The fault function is disabled when in `sleep' mode, i.e., FAULT goes high and the 30 µA output sinks are turned off. The FAULT output is a switched current sink of typically 60 µA. Each channel consists of a TTL/CMOS-compatible logic input gated with a common ENABLE input. A logic high at the input will provide drive to turn on the output npn switch. Each output has a current-limit circuit that limits the output current by detecting the voltage drop across a low-value internal resistor in the emitter of the output switch. If this drop reaches a threshold, then the base drive to the output switch is reduced to maintain constant current in the output. To keep the device within its safe operating area (SOA) this output current limit is further reduced
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5
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