UCC2912 Datasheet, PDF (1/16 Pages) Texas Instruments – PROGRAMMABLE HOT SWAP POWER MANAGER

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D Integrated 0.15-Ω Power MOSFET
D 3-V to 8-V Operation
D Digital Programmable Current Limit
from 0 A to 3 A
D Electronic Circuit Breaker Function
D 1µA I_CC When Disabled
D Programmable On-Time
D Programmable Start Delay
D Fixed 3% Duty Cycle
UCC2912
UCC3912
PROGRAMMABLE HOT SWAP POWER MANAGER
SLUS241D − MARCH 1994 - REVISED NOVEMBER 2003
D Unidirectional Switch
D Thermal Shutdown
D Fault-Output Indicator
D Maximum-Output Current Can Be Set to 1 A
Above the Programmed Fault Level or to a
Full 4 A
D Power SOIC, Low-Thermal Resistance
Packaging
description
The UCC3912 family of hot swap power managers provides complete power management, hot swap capability,
and circuit breaker functions. The only component required to operate the device, other than supply bypassing,
is the fault timing capacitor, C_T. All control and housekeeping functions are integrated, and externally
programmable. These include the fault current level, maximum output-sourcing current, maximum fault time,
and startup delay. In the event of a constant fault, the internal fixed 3% duty cycle ratio limits average output
power.
The internal 4-bit DAC allows programming of the fault level current from 0 A to 3 A with 0.25-A resolution. The
IMAX control pin sets the maximum sourcing current to 1 A above the fault level when driven low, and to a full
4 A when driven high for applications which require fast output capacitor charging.
When the output current is below the fault level, the output MOSFET is switched on with a nominal on resistance
of 0.15 Ω. When the output current exceeds the fault level, but is less than the maximum sourcing level, the
output remains switched on, but the fault timer starts charging C_T. Once C_T charges to a preset threshold, the
switch is turned off, and remains off for 30 times the programmed fault time. When the output current reaches
the maximum sourcing level, the MOSFET transitions from a switch to a constant current source. (continued)
block diagram
IMAX 10
H=4A
CHARGE
PUMP
REVERSE VOLTAGE
COMPARATOR
4A
1A
ABOVE
FAULT
0 A−3 A
0.25
RES
MAX CURRENT
LEVEL
CURRENT SENSE
+
−
LINEAR CURRENT AMPLIFIER
CURRENT FAULT
+
LEVEL 0A TO 3 A
−
OVERCURRENT
COMPARATOR
ON TIME
CONTROL
3% DUTY
CYCLE
THERMAL
SHUTDOWN
INTERNAL
BIAS
30 mV
−
+
VOUT
H = OPEN
2 VIN
3 VIN
POWER
FET
1.5 V
+
−
14 VOUT
15 VOUT
1 SHTDWN
6789
B3 B2 B1 B0
4 BIT DAC
5 4 13 12
11
GND _HEATSINK
CT
GND PINS
16
FAULT
UDG-99146
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright  2003, Texas Instruments Incorporated
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