UCC3912 Datasheet, PDF (1/6 Pages) Texas Instruments – Programmable Hot Swap Power Manager

Programmable Hot Swap Power Manager
application
INFO
available
UCC3912
FEATURES
• Integrated 0.15Ω Power MOSFET
• 3V to 8V Operation
• Digital Programmable Current Limit
from 0 to 3A
• Electronic Circuit Breaker Function
• 1µA I_CC when Disabled
• Programmable on Time
• Programmable Start Delay
• Fixed 3% Duty Cycle
• Uni-Directional Switch
• Thermal Shutdown
• Fault Output Indicator
• Maximum Output Current can be set
to 1A above the Programmed Fault
Level or to a full 4A
• Power SOIC, Low Thermal
Resistance Packaging
DESCRIPTION
The UCC3912 Hot Swap Power Manager provides complete power man-
agement, hot swap capability, and circuit breaker functions. The only com-
ponent required to operate the device, other than supply bypassing, is the
fault timing capacitor, C_T. All control and housekeeping functions are inte-
grated, and externally programmable. These include the fault current level,
maximum output sourcing current, maximum fault time,and start-up 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
to 3A with 0.25A resolution. The IMAX control pin sets the maximum sour-
cing current to 1A above the fault level when driven low, and to a full 4A
when driven high for applications which require fast output capacitor charg-
ing.
When the output current is below the fault level, the output MOSFET is
switched on with a nominal on resistance of 0.15 . When the output cur-
rent 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 re-
mains 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
4A
1A
ABOVE
FAULT
MAX
CURRENT
LEVEL
CURRENT FAULT
LEVEL 0–3 AMPS
0–3A
0.25
RES
CHARGE
PUMP
REVERSE VOLTAGE
COMPARATOR
30mV
V_OUT
CURRENT SENSE
H = OPEN
LINEAR CURRENT
AMPLIFIER
2
VIN
3
POWER
FET
OVER CURRENT
COMPARATOR
ON TIME
CONTROL
3% DUTY
CYCLE
THERMAL
SHUTDOWN
INTERNAL
BIAS
14
VOUT
15
1.5V
+
–
1 SHTDWN
6
7
8
9
B3 B2 B1 B0
4 BIT DAC
SLUS241A - NOVEMBER 1999
5 4 13 12
GND HEAT SINK
GND PINS
11
16
CT
FAULT
UDG-99146