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UCC381-5 Datasheet Preview

UCC381-5 Datasheet

Low Dropout 1 Ampere Linear Regulator

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UCC281-3/-5/-ADJ
UCC381-3/-5/-ADJ
Low Dropout 1 Ampere Linear Regulator Family
FEATURES
Precision Positive Linear Voltage
Regulation
0.5V Dropout at 1A
Guaranteed Reverse Input/ Output
Voltage Isolation with Low Leakage
Low Quiescent Current Irrespective of
Load
Adjustable Output Voltage Version
Fixed Versions for 3.3V and 5V
Outputs
Logic Shutdown Capability
Short Circuit Power Limit of
3% VIN Current Limit
Remote Load Voltage for Accurate
Load Regulation
DESCRIPTION
The UCC381-3/-5/-ADJ family of positive linear series pass regulators is
tailored for low drop out applications where low quiescent power is impor-
tant. Fabricated with a BiCMOS technology ideally suited for low input to
output differential applications, the UCC381 will pass 1A while requiring
only 0.5V of input voltage headroom. Dropout voltage decreases linearly
with output current, so that dropout at 200mA is less than 100mV. Quies-
cent current is always less than 650µA. To prevent reverse current conduc-
tion, on-chip circuitry limits the minimum forward voltage to typically 50mV.
Once the forward voltage limit is reached, the input-output differential volt-
age is maintained as the input voltage drops until undervoltage lockout dis-
ables the regulator.
UCC381-3 and UCC381-5 versions have on-chip resistor networks preset
to regulate either 3.3V or 5.0V, respectively. Furthermore, remote sensing
of the load voltage is possible by connecting the VOUTS pin directly at the
load. The output voltage is then regulated to 1.5% at room temperature and
better than 2.5% over temperature. The UCC381-ADJ version has a regu-
lated output voltage programmed by an external user-definable resistor ra-
tio.
(continued)
BLOCK DIAGRAM
VIN 8
1.3/2.1A
CURRENT
REFERENCE
CURRENT
LIMIT
+
SHUTDOWN FOR FIXED VERSIONS
CT* 5
0.65V
*ADJ
VERSION
ONLY
3% DUTY CYCLE
CURRENT LIMIT TIMER
REVERSE VOLTAGE
SENSE
THERMAL
SHUTDOWN
SLUS214B -JANUARY 2001
VPUMP
UVLO
VOLTAGE
AMPLIFIER
+
R2
1.25V
R1
1 VOUT
4 VOUTS
2 GND
3 GND
6 GND
7 GND
UCC381-ADJ
UCC381-3
UCC381-5
R2 R1
0 OPEN
82k 50k
150k 50k
UDG-98112




Unitrode

UCC381-5 Datasheet Preview

UCC381-5 Datasheet

Low Dropout 1 Ampere Linear Regulator

No Preview Available !

UCC281-3/-5/-ADJ
UCC381-3/-5/-ADJ
ABSOLUTE MAXIMUM RATINGS
VIN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9V
CT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 to 3V
Storage Temperature . . . . . . . . . . . . . . . . . . . 65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . 55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
CONNECTION DIAGRAMS
SOIC-8 (Top View)
DP Package
VOUT 1
Currents are positive into, negative out of the specified terminal.
Consult Packaging Section of Databook for thermal limitations
and considerations of packages. All voltages are referenced to
GND.
GND 2
GND 3
VOUTS 4
8 VIN
7 GND
6 GND
5 CT*
DESCRIPTION (cont.)
Short circuit current is internally limited. The device re-
sponds to a sustained overcurrent condition by turning
off after a TON delay. The device then stays off for a pe-
riod, TOFF, that is 32 times the TON delay. The device
then begins pulsing on and off at the TON /(TON+TOFF)
duty cycle of 3%. This drastically reduces the power dis-
sipation during short circuit such that heat sinking, if at all
required, must only accommodate normal operation. On
the fixed output versions of the device TON is fixed at
400µs a guaranteed minimum. On the adjustable ver-
sion an external capacitor sets the on time. The off time
is always 32 times TON.
* ADJ version only
The UCC381 can be shutdown to 25µA (max) by pulling
the CT pin low.
Internal power dissipation is further controlled with ther-
mal overload protection circuitry. Thermal shutdown oc-
curs if the junction temperature exceeds 165°C. The chip
will remain off until the temperature has dropped 20°C.
The UCC281 series is specified for operation over the in-
dustrial range of 40°C to +85°C, and the UCC381 se-
ries is specified from 0°C to +70°C. These devices are
available in the 8 pin DP surface mount power package.
For other packaging options consult the factory.
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications hold for TA = 0°C to 70°C for the
UCC381-X series and 40°C to +85°C for the UCC283-X series, VIN = VOUT + 1.5V, IOUT = 0mA, COUT = 2.2µF. CT = 1500pF for
the UCC381-ADJ version and VOUT set to 5V. TJ = TA.
PARAMETER
TEST CONDITIONS
MIN TYP MAX UNITS
UCC381-5 Fixed 5V, 1A Family
Output Voltage
TJ = 25°C
4.925 5 5.075 V
Over Temperature
4.875
5.125 V
Line Regulation
Load Regulation
VIN = 5.15V to 9V
IOUT = 0mA to 1A
1 3 mV
2 5 mV
Drop Out Voltage, VIN – VOUT
Peak Current Limit
IOUT = 1A, VOUT = 4.85V, TA < 85°C
IOUT = 200mA, VOUT = 4.85V, TA < 85°C
VOUT = 0V
0.5 0.6
V
100 200 mV
2 3.5 A
Overcurrent Threshold
1 1.8 A
Current Limit Duty Cycle
Overcurrent Time Out, TON
Quiescent Current
VOUT = 0V
VOUT = 0V
3 5%
400 750 1600 µs
400 650 µA
Quiescent Current in Shutdown
Shutdown Threshold
Reverse Leakage Current
VIN = 9V
At CT Input
1V < VIN < VOUT, VOUT < 5.1V, at VOUT
10
0.25 0.65
25
75
µA
V
µA
UVLO Threshold
VIN where VOUT passes current
2.5 2.8 3.0
V
2


Part Number UCC381-5
Description Low Dropout 1 Ampere Linear Regulator
Maker Unitrode
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UCC381-5 Datasheet PDF






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