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8187
LOW-DROPOUT, 3.3 V REGULATOR
— HIGH EFFICIENCY
Designed specifically to meet the requirement for extended opera-
tion of battery-powered equipment such as cordless and cellular
telephones, the A8187SLT voltage regulator offers the reduced dropout
voltage and quiescent current essential for maximum battery life.
T3.3 V
CVR
PRODUONLY1 2
3
INUED ENCEDwg.PS-022-1
Applicable also to palmtop computers and personal data assistants, the
device delivers a regulated, continuous 3.3 V output at up to 75 mA
under normal operating conditions, or to 150 mA (transient) under
worst-case conditions.
A PMOS pass element provides a typical dropout voltage of only
85 mV at 60 mA of load current. The low dropout voltage permits
deeper battery discharge before output regulation is lost. Furthermore,
quiescent current does not increase as the dropout voltage is ap-
proached, an ideal feature in standby/resume power systems where
data integrity is crucial. Regulator accuracy and excellent temperature
characteristics are provided by a bandgap reference.
This device is supplied in a small-outline plastic transistor package
(SOT-89/TO-243AA) for surface-mount applications. The A8187SLT is
rated for operation over a temperature range of -20°C to +85°C. A
similar device with an ENABLE input for control over sequential power
up, standby, or power down is the A8186SLU.
ONT EFERABSOLUTE MAXIMUM RATINGS
C RInput Voltage, VI . . . . . . . . . . . . . . 10 V
Output Current, IO . . . . . . . . . 150 mA*
IS ROperating Temperature Range,
D OTA . . . . . . . . . . . . . -20°C to +85°C
FJunction Temperature, TJ . . . +150°C
Storage Temperature Range,
TS . . . . . . . . . . . . -40°C to +150°C
FEATURES AND BENEFITS
I High Efficiency Provides Extended Battery Life
I 85 mV Typical Dropout Voltage at IO = 60 mA
I 45 µA Typical Quiescent Current at VI = 6 V
I Up to 150 mA Output Current
I Internal Thermal Protection
I Surface-Mount Package
APPLICATIONS
I Cordless and Cellular Telephones
* 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.
I Personal Data Assistants
I Personal Communicators
I Palmtop Computers
† Fault conditions that produce excessive junction
temperature will activate device thermal
shutdown circuitry. These conditions can be
tolerated but should be avoided.
Always order by complete part number: A8187SLT .

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8187
LOW-DROPOUT,
3.3 V REGULATOR
FUNCTIONAL BLOCK DIAGRAM
IN 1
BIAS
GND 2
DRIVE
3 OUT
ERROR
AMP
BANDGAP
REF.
TAB
Dwg. FS-012-4
MAXIMUM ALLOWABLE OUTPUT CURRENT with device mounted on 2.24" x 2.24"
(56.9 mm x 56.9 mm) solder-coated copper-clad board in still air.
TA
25°C
Maximum Allowable Output Current in Milliamperes with VI = 8 V, TJ = 150°C, Period 10 s*
dc (Duty Cycle)
100%
90%
80%
70%
60%
50%
40%
30%
100 115 125 145 150 150 150 150
20%
150
50°C
80
90 100 115 135 150 150 150 150
70°C
65
70
80
90 110 130 150 150 150
85°C
50
60
65
75
85 105 130 150 150
* IO = (TJ - TA)/([VI - VO] RθJA • dc) = (150 - TA)/(4.7 • 258 • dc)
Output current rating can be increased (to 150 mA maximum) by heat sinking or reducing the input voltage. Conditions that produce excessive
junction temperature will activate device thermal shutdown circuitry. These conditions can be tolerated but should be avoided.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1995, 2000 Allegro MicroSystems, Inc.

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8187
LOW-DROPOUT,
3.3 V REGULATOR
ELECTRICAL CHARACTERISTICS at TA = +25°C (unless otherwise noted).
Limits
Characteristic
Symbol Test Conditions
Min.
Typ.
Max.
Output Voltage
VO 4 V VI 8 V,
TA = +25°C
10 µA IO 100 mA* -20°C TA +85°C
Output Volt. Temp. Coeff.
VI = 3.3 V, IO = 60 mA*, -20°C TA +85°C
αVO VI = 6 V, IO = 10 mA
Line Regulation
Load Regulation
VO(VI)
VO(IO)
6 V VI 8 V, IO = 1 mA
4 V VI 6 V, IO = 1 mA
1 mA IO 100 mA*, VI = 8 V
1 mA IO 100 mA*, VI = 6 V
1 mA IO 100 mA*, VI = 4 V
Dropout Voltage
VImin - VO IO = 60 mA*
Quiescent Current
IO = 125 mA*
IQ VI = 6 V, 1 mA IO 100 mA*
(GND terminal current)
VI = 8 V, 1 mA IO 100 mA*
Thermal Shutdown Temp.
TJ
Thermal Resistance
RθJA Mounted on 2.24" x 2.24" solder-coated
copper-clad board in still air
Typical values are at TA = +25°C and are given for circuit design information only.
* Pulse test (20 ms). See previous page for duty cycle limitations.
3.25
3.20
3.00
150
3.30
3.30
8.0
10
20
13
8.0
85
190
45
50
258
3.35
3.40
±1.0
12
20
30
25
20
150
300
60
65
Units
V
V
V
mV/°C
mV
mV
mV
mV
mV
mV
mV
µA
µA
°C
°C/W

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8187
LOW-DROPOUT,
3.3 V REGULATOR
TYPICAL CHARACTERISTICS
LOAD REGULATION
LINE REGULATION
3.36
3.34
3.32
3.30
VI = 8 V
VI = 6 V
3.28
3.26
3.24
TA = -20°C
V =4V
I
3.22
0
25 50 75 100
OUTPUT CURRENT in mA
125 150
Dwg. GP-052-6
3.36
3.34
3.32
3.30
3.28
3.26
3.24
3.22
2.0
TA = -20°C
50 mA INTERVALS
IO = 100 mA
IO = 0 mA
3.0 4.0 5.0 6.0
INPUT VOLTAGE in VOLTS
7.0 8.0
Dwg. GP-053-6
3.36
3.34
3.32
3.30
VI = 8 V
3.28
3.26
3.24
TA = 25°C
2 V INTERVALS
V =4V
I
3.22
0
25 50 75 100
OUTPUT CURRENT in mA
125 150
Dwg. GP-052-7
3.36
3.34
3.32
3.30
3.28
3.26
3.24
3.22
2.0
IO = 0 mA
TA = 25°C
50 mA INTERVALS
IO = 100 mA
3.0 4.0 5.0 6.0
INPUT VOLTAGE in VOLTS
7.0 8.0
Dwg. GP-053-7
CAUTION: Maximum allowable duty cycle will be significantly less than 100% at high temperatures, at high input voltages, or at high output currents.
See Maximum Allowable Output Current table.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

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8187
LOW-DROPOUT,
3.3 V REGULATOR
TYPICAL CHARACTERISTICS (cont’d)
LOAD REGULATION
LINE REGULATION
3.36
3.34
3.32
3.36
3.34
3.32
TA = 85°C
50 mA INTERVALS
3.30
3.28
VI = 8 V
3.30
IO = 0 mA
3.28
3.26
3.24
TA = 85°C
2 V INTERVALS
VI = 4 V
3.22
0
25 50 75 100
OUTPUT CURRENT in mA
125 150
Dwg. GP-052-8
3.26
3.24
3.22
2.0
IO = 100 mA
3.0 4.0 5.0 6.0
INPUT VOLTAGE in VOLTS
7.0 8.0
Dwg. GP-053-8
OUTPUT VOLTAGE
3.5
3.0
VI = 6 V
2.5
3.31
IO = 0
2.0 3.30
1.5 3.29
IO = 0 - 100 mA
1.0
TA = 25°C
3.28
0.5
0
0
1.0 2.0 3.0
INPUT VOLTAGE in VOLTS
4.0
Dwg. GP-059-1
-50
0 +50
AMBIENT TEMPERATURE in °C
+100
Dwg. GP-050-2
CAUTION: Maximum allowable duty cycle will be significantly less than 100% at high temperatures, at high input voltages, or at high output currents.
See Maximum Allowable Output Current table.