A2557SEB-T Allegro Microsystems Inc, A2557SEB-T Datasheet

A2557SEB-T

Manufacturer Part Number
A2557SEB-T
Description
Manufacturer
Allegro Microsystems Inc
Datasheet

Specifications of A2557SEB-T

Switch Type
Low Side
Power Switch Family
A2557
Input Voltage
7V
Output Current
300mA
Number Of Outputs
4
Mounting
Surface Mount
Supply Current
30mA
Package Type
PLCC
Operating Temperature (max)
85C
Operating Temperature Classification
Commercial
Pin Count
28
Lead Free Status / Rohs Status
Compliant
Features and Benefits
▪ 300 mA output current per channel
▪ Independent overcurrent protection and thermal limiting
▪ Output voltage to 60 V
▪ Output SOA protection
▪ Fault-detection circuitry for open or shorted load
▪ Low quiescent current Sleep Mode
▪ Integral output flyback/clamp diodes
▪ TTL- and 5 V CMOS-compatible inputs
Packages:
Not to scale
29317.16M
for each driver
Package B, 16-pin DIP
with exposed tabs
Package LB, 16-pin SOIC
with internally fused pins
ENABLE
IN N
Package EB, 28-pin PLCC
with internally fused pins
V CC
Functional Block Diagram
ONE OF FOUR DRIVERS
COMMON CONTROL
with Fault Detection and Sleep Mode
CONTROL
SLEEP
THERMAL
LIMIT
Description
The A2557 has 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.
Overcurrent 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).
Continued on the next page…
CURRENT
LIMIT
Protected Quad Driver
+
<<1
60 A
2.5 V
30 A
FAULT
K
OUT N
A2557

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A2557SEB-T Summary of contents

Page 1

Features and Benefits ▪ 300 mA output current per channel ▪ Independent overcurrent protection and thermal limiting for each driver ▪ Output voltage ▪ Output SOA protection ▪ Fault-detection circuitry for open or shorted load ▪ Low ...

Page 2

... A2557KLBTR-T Yes A2557SB-T* Yes A2557SEBTR-T* Yes A2557SLBTR-T* Yes *Variant is in production but has been determined to be LAST TIME BUY. This classification indicates that the variant is obsolete and notice has been given. Sale of the variant is currently restricted to existing customer applications. The variant should not be purchased for new design applications because of obsolescence in the near future ...

Page 3

A2557 Absolute Maximum Ratings Characteristic Logic Supply Voltage Input Voltage Output Voltage Overcurrent Protected Output Voltage Output Current FAULT Output Voltage Package Power Dissipation Operating Ambient Temperature Maximum Junction Temperature Storage Temperature with Fault Detection and Sleep Mode Symbol V ...

Page 4

A2557 GROUND GROUND with Fault Detection and Sleep Mode Pin-out Diagrams EB (PLCC) Package (DIP) and LB (SOIC) Packages IN OUT ...

Page 5

A2557 ELECTRICAL CHARACTERISTICS over operating temperature range, V Characteristic Symbol Output Leakage Current* Output Sustaining Voltage Output Saturation Voltage Over-Current Limit Input Voltage Input Current Fault Output Leakage Current Fault Output Current Fault Output Saturation Voltage V Clamp Diode Forward ...

Page 6

... Dwg. GP-064 400 300 Dwg. GP-066 Protected Quad Driver 10 20 OUTPUT VOLTAGE IN VOLTS IN SWITCHING (FROM SLEEP) ENABLE SWITCHING IN SWITCHING (AWAKE) 0 100 200 OUTPUT CURRENT IN MILLIAMPERES Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com Dwg. GP-065 T ...

Page 7

... V. This helps to improve SOA by immediately reducing the OUT FAULT N peak power pulse into a shorted load at high logic low at the ENABLE input causes all outputs to be switched off regardless of the state of the IN terminals. In addi tion, the device is put into a low quiescent current ‘sleep’ mode reducing the inputs go high, the circuit will ‘ ...

Page 8

A2557 CIRCUIT DESCRIPTION AND APPLICATION (continued) NORMAL LAMP IN-RUSH CURRENT THERMAL GRADIENT SENSING CURRENT LIMIT I TRIP 0 TIME Inductive load driver Bifi lar (unipolar) stepper motors (and other inductive loads) can be driven directly. The internal diodes prevent damage ...

Page 9

A2557 CIRCUIT DESCRIPTION AND APPLICATION (continued) IN FAULT (SHORTED LOAD) FAULT (OPEN LOAD) Under some conditions it is possible to get spurious glitches on the FAULT output at load turn-on and turn-off transitions: • Light load turn-off. Under light loading ...

Page 10

A2557 19.05±0. 1.27 MIN +0.25 1.52 –0.38 0.46 ±0.12 with Fault Detection and Sleep Mode B Package, 16-pin DIP with internally fused pins 4, 5, 12, and 13 and external thermal tabs +0.76 +0.38 6.35 10.92 ...

Page 11

A2557 with internally fused pins 5 through 11 and 19 through 25 12.45±0.13 11.51±0.08 0.74 ±0.08 28X 0.10 0.43 ±0.10 A Terminal #1 mark area with Fault Detection and Sleep Mode EB Package, 28-pin PLCC 12.45±0.13 11.51±0. ...

Page 12

A2557 with internally fused pins 4 and 5, and 12 and 13 10.30±0. 16X 0.10 C 1.27 0.41 ±0.10 For Reference Only Pins 4 and 5, and 12 and 13 internally fused Dimensions in millimeters (reference ...

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