1
2
3
Dwg. PD-0xx
7.7 V
VR
VR
7.7 V
2
3
1
Data Sheet
27468.22
LOW-DROPOUT,
7.7 V PREREGULATOR
Designed specifically to meet the stringent requirements of automo-
tive applications, the A8178LLR and A8178LLT provide an output
voltage of 7.7 V
15% for supply voltages greater than 6.9 V. They
also provide a low-dropout tracking output for supply voltages down to
2.5 V. These regulators are intended to be used with sensitive automo-
tive electronics systems that do not have the capability of low dropout
operation and cannot withstand the high-voltage transients typical of
automotive applications. These 7.7 V preregulators will withstand all
ISO pulses (ignition coil disconnect requires an external diode) and will
continue to operate during positive power supply transients (noise).
These devices are supplied in small-outline plastic transistor
packages for surface-mount applications. The A8178LLR is supplied in
the minimum footprint SOT-23/TO-236AB; the A8178LLT is furnished in
the SOT-89/TO-243AA for increased allowable package power dissipa-
tion.
ABSOLUTE MAXIMUM RATINGS
Input Voltage, V
I
. . . . . . . . . . . . . . 30 V
Reverse Input Voltage, V
RI
. . . . -120 V
Output Current, I
O
. . . . . . . . . . . . TBD*
Operating Temperature Range,
T
A
. . . . . . . . . . . . -40
C to +150
C
Junction Temperature, T
J
. . . . +150
C
Storage Temperature Range,
T
S
. . . . . . . . . . . . -40
C to +170
C
* Output current rating is limited by input voltage,
duty cycle, and ambient temperature. Under
any set of conditions, do not exceed a junction
temperature of +150
C. See next page.
T
his document contains information on a product under development. Allegro
MicroSystems, Inc. reserves the right to change or discontinue this product without
notice.
Always order by complete part number:
A8178LLT
.
8178
PRODUCT PREVIEW
(Subject to change without notice)
April 5, 1996
8178
LOW-DROPOUT,
7.7 V PREREGULATOR
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ELECTRICAL CHARACTERISTICS over operating temperature range.
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Output Voltage
V
O
6.9 V
V
I
24 V
6.5
7.7
8.8
V
2.5 V
V
I
6.9 V
V
I
- 0.4
--
--
V
V
I
= 120 V, pulse test
--
--
11
V
Output Volt. Temp. Coeff.
VO
--
--
TBD
mV/
C
Line Regulation
V
O(
VI)
--
--
TBD
mV
Load Regulation
V
O(
IO)
--
--
TBD
mV
Quiescent Current
I
Q
V
I
= 13.5 V, I
O
= 0
--
--
2.5
mA
2.5 V
V
I
8 V, I
O
= 0
--
--
5.6
mA
Power Dissipation
P
d
V
I
= 13.5 V, I
O
= 15 mA
--
--
130
mW
Thermal Resistance*
R
JA
A8178LLR
--
575
--
C/W
A8178LLT
--
200
--
C/W
Typical values are at T
A
= +25
C and are given for circuit design information only.
*
Mounted on 2.24" x 2.24" solder-coated copper-clad board in still air.
INTERNAL PROTECTIVE FEATURES
ISO
Pulse No.
Test
Test Conditions (at T
A
= +25
C)
1
Inductive Turn Off (Negative)
V
S
= -100 V, R
S
= 10
, t
r
= 1
s, t
d
= 2 ms
2
Inductive Turn Off (Positive)
V
S
= 100 V, R
S
= 10
, t
r
= 1
s, t
d
= 50
s, non-operating
3a
Capacitive/Inductive Coupling (Neg)
V
S
= -150 V, R
S
= 50
, t
r
= 50 ns, t
d
= 100 ns
3b
Capacitive/Inductive Coupling (Pos)
V
S
= 100 V, R
S
= 50
, t
r
= 50 ns, t
d
= 100 ns
4
Reverse Battery
V
S
= -14 V, t
d
= 20 s, non-operating
5
Load Dump
V
S
= 86.5 V, R
S
= 0.5
, t
r
= 5 ms, t
d
= 400 ms
6
Ignition Coil Disconnect
V
S
= -300 V, R
S
= 30
, t
r
= 60
s, t
d
= 300
s
EXTERNAL PROTECTION REQ'D
7
Field Decay (Negative)
V
S
= -80 V, R
S
= 10
, t
r
= 5 ms, t
d
= 100 ms
Copyright 1996 Allegro MicroSystems, Inc.
Dimensions in Millimeters
(controlling dimensions)
A8178LLR
Dimensions in Inches
(for reference only)
NOTES: 1. Lead spacing tolerance is non-cumulative.
2. Exact body and lead configuration at vendor's option within limits shown.
Dwg. MA-010 in
1
2
3
0.004
0.0005
0.044
0.035
0.007
0.003
0.120
0.110
0.055
0.047
0.1039
0.083
0.040
0.035
0.027
REF
0.024
0.018
0.020
0.015
0.080
0.070
Dwg. MA-010 mm
1
2
3
0.10
0.013
1.12
0.89
0.18
0.085
3.04
2.80
1.40
1.20
2.64
2.10
1.03
0.89
0.69
REF
0.60
0.45
0.51
0.37
2.05
1.78
8178
LOW-DROPOUT,
7.7 V PREREGULATOR
8178
LOW-DROPOUT,
7.7 V PREREGULATOR
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Dwg. MA-009-3 in
1
2
3
0.064
0.072
0.155
0.167
0.059
BSC
0.014
0.019
0.035
0.047
0.090
0.102
0.055
0.063
0.014
0.017
0.084
0.090
0.017
0.022
0.118
BSC
0.173
0.181
Dimensions in Millimeters
(controlling dimensions)
Dwg. MA-009-3 mm
1
2
3
4.40
4.60
1.62
1.83
3.94
4.25
1.50
BSC
0.36
0.48
0.89
1.20
2.29
2.60
1.40
1.60
0.35
0.44
2.13
2.29
0.44
0.56
3.00
BSC
A8178LLT
Dimensions in Inches
(for reference only)
NOTES: 1. Lead spacing tolerance is non-cumulative.
2. Exact body and lead configuration at vendor's
option within limits shown.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, such
departures from the detail specifications as may be required to permit improvements
in the design of its products.
The information included herein is believed to be accurate and reliable.
However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for
any infringements of patents or other rights of third parties which may result from its
use.
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