8188
PRELIMINARY INFORMATION
(subject to change without notice)
July 13, 1999
LOW-DROPOUT REGULATORS
— HIGH EFFICIENCY
Designed specifically to meet the requirement for extended opera-
tion of battery-powered equipment such as cordless and cellular tele-
phones, the A8188S— voltage regulators offer the reduced dropout
voltage and quiescent current essential for maximum battery life.
Applicable also to palmtop computers and personal data assistants,
these devices deliver a regulated output at up to 250 mA (transient),
which is limited only by package power dissipation. Regulated output
voltages between 2.5 V and 3.3 V are trimmed at wafer probe.
A PMOS pass element provides a typical dropout voltage of only
90 mV at 60 mA of load current. The low dropout voltage permits
deeper battery discharge before output regulation is lost. Quiescent
current does not increase significantly 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. The A8188SL-xx
includes ENABLE inputs to give the designer complete control over
power up, standby, or power down.
These devices are supplied, without the ENABLE function, in a
standard 3-lead SOT-89/TO-243AA small-outline plastic transistor
package (suffix ‘LT’). Dual regulators (A8188SL-xx) are provided in
an 8-lead SOIC package. All devices are rated for operation over a
temperature range of -20°C to +85°C.
Data Sheet
27468.8
A8188SLT-xx
where “-xx” is the required output voltage in tenths
ABSOLUTE MAXIMUM RATINGS
Input Voltage, V
I
. . . . . . . . . . . . . .
10 V
Peak Output Current,
I
OM
. . . . . . . . . . . . . . . . . .
250 mA*
Enable Input Voltage, V
E
. . . . . . . . .
V
I
Operating Temperature Range,
T
A
. . . . . . . . . . . . .
-20
°
C to +85
°
C
Junction Temperature, T
J
. . . .
+150
°
C
†
Storage Temperature Range,
T
S
. . . . . . . . . . . .
-40
°
C to +150
°
C
* Output current rating is limited by input
voltage, duty cycle, and ambient tempera-
ture. Under any set of conditions, do not
exceed a junction temperature of +150°C.
See following pages.
† Fault conditions that produce excessive
junction temperature will activate device
thermal shutdown circuitry. These condi-
tions can be tolerated but should be
avoided.
T
C
U Y
D L
O N
R O
P E
D C
E N
U E
IN ER
T F
N E
O R
C R
IS O
D F
—
VR
1
2
3
GND
Dwg. PS-022-2
OUT
IN
FEATURES AND BENEFITS
I
High Efficiency Provides Extended Battery Life
I
90 mV Typical Dropout Voltage at I
O
= 60 mA
I
55
µA
Typical Quiescent Current
Less Than 1
µA
“Sleep” Current
I
250 mA Peak Output Current
I
Improved PSRR and Transient Performance
I
Internal Thermal Protection
APPLICATIONS
I
I
I
I
Cordless and Cellular Telephones
Personal Data Assistants
Personal Communicators
Palmtop Computers
Always order by complete part number, e.g.,
A8188SLT-30
.
8188
LOW-DROPOUT
REGULATORS
FUNCTIONAL BLOCK DIAGRAM
(1/2 of A8188SL-xx shown)
IN
8
1
OUT
BIAS
DRIVE
ERROR
AMP
ENABLE
7
ENABLE
BANDGAP
REF.
2
GND
Dwg. FS-012-8
Always order by complete part number:
Part Number
A8188SL-xx
A8188SLT-xx
Package
8-Lead SOIC
3-Lead SOT-89/TO-243AA
R
θJA
108°C/W
258°C/W
where “-xx” is the required output voltage (V
O(nom)
) in tenths
(25 through 33), e.g., -30 = 3.0 volts.
OUT
1
GND
1
A8188SL-xx
8
VR
7
6
VR
5
IN
1
1
1
2
3
4
ENABLE
IN
OUT
2
GND
2
2
ENABLE
2
Dwg. PS-023
NOTE — There is an indeterminate resistance between terminals
2 and 4. For proper operation, terminals 2 and 4 must be
externally connected together.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1999, 2000 Allegro MicroSystems, Inc.
8188
LOW-DROPOUT
REGULATORS
A8188SL-xx Maximum Allowable Total Average 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.
Allowable Total Average (10 ms) Output Current in Milliamperes with T
J
= 150°C, Duty Cycle = 100%†
V
I
- V
O
T
A
25°C
50°C
70°C
85°C
1.0
500
500
500
500
1.5
500
500
490
400
2.0
500
460
370
300
2.5
460
370
295
240
3.0
385
305
245
200
4.0
285
230
185
150
5 .0
230
185
145
120
6.0
190
150
120
100
7.0*
165
130
105
85
* Absolute maximum peak output current rating for either output is 250 mA; absolute maximum input voltage is 10 V.
† I
O
= (T
J
– T
A
)/([V
I
– V
O
] R
θJA
x dc) = (150 – T
A
)/([V
I
– V
O
] x 108 x 1.00)
Output current rating can be increased (to 250 mA maximum per output) by additional heat sinking or reducing the duty
cycle. Conditions that produce excessive junction temperature will activate device thermal shutdown circuitry. These
conditions can be tolerated but should be avoided.
A8188SLT-xx 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.
Allowable Average (10 ms) Output Current in Milliamperes with T
J
= 150°C, Duty Cycle = 100%†
V
I
- V
O
T
A
25°C
50°C
70°C
85°C
1.0
250
250
250
250
1.5
250
250
205
165
2.0
240
190
155
125
2.5
190
155
120
100
3.0
160
125
100
80
4.0
120
95
75
60
5.0
95
75
60
50
6.0
80
65
50
40
7.0*
65
55
40
35
* Absolute maximum input voltage is 10 V.
† I
O
= (T
J
– T
A
)/([V
I
– V
O
] R
θJA
x dc) = (150 – T
A
)/([V
I
– V
O
] x 258 x 1.00)
Output current rating can be increased (to 250 mA maximum) by additional heat sinking or reducing the duty cycle.
Conditions that produce excessive junction temperature will activate device thermal shutdown circuitry. These conditions
can be tolerated but should be avoided.
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