Datasheet

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     

SLUS198C – FEBUARY 2000 - REVISED - JUNE 2001
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
pin descriptions
B0 – B3: These pins provide digital input to the DAC, which sets the fault-current threshold. They can be used
to provide a digital soft-start and adaptive-current limiting.
CT: A capacitor connected to ground sets the maximum-fault time. The maximum-fault time must be more than
the time required to charge the external capacitance in one cycle. The maximum-fault time is defined as
T
FAULT
= 16.1 × 10
3
× C
T
. Once the fault time is reached the output will shutdown for a time given by
T
SD
= 833 × 10
3
× C
T
, this equates to a 1.9% duty cycle.
FAULT
: Open-drain output, which pulls low upon any fault or interrupt condition, or thermal shutdown.
IMAX: When this pin is set to a logic low, the maximum-sourcing current will always be 1 A above the
programmed-fault level. When set to a logic high, the maximum-sourcing current will be a constant 4 A for
applications which require fast charging of load capacitance.
SHTDWN
: When this pin is brought to a logic low, the IC is put into a sleep mode drawing typically less than
100 µA of I
CC
.The input threshold is hysteretic, allowing the user to program a startup delay with an external
RC circuit.
VIN: Input voltage to the UCC3915. The recommended voltage range is 7 V to 15 V. Both VIN pins should be
connected together and connected to the power source.
VOUT: Output voltage from the UCC3915. Both VOUT pins should be connected together and connected to
the load. When switched the output voltage will be approximately V
IN
– (0.15 Ω × I
OUT
). VOUT must not exceed
VIN by greater than 0.3 V.
APPLICATION INFORMATION
UDG-99175
6 7 8 9
11
10
B0B1B2B3 IMAX
16
3
2
4 12 13 5
14
15
1SHTDWN
VOUT
VIN
FAULT
CT
GND
HEAT SINK
GND PINS
UCC3915
R
L
C
OUT
V
OUT
C
SD
R
SD
V
IN
C
IN
D1
C
T
S1 S2 S3 S4 S5
DIP
SWITCH
S6
V
IN
V
IN
R1
LED5 V
Figure 1. Evaluation Circuit