UC1914
UC2914
UC3914
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . 40V
Maximum Forced Voltage
SD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12V
IMAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VCC
LR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12V
Maximum Current
FAULT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
PLIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA
Maximum Voltage, FAULT . . . . . . . . . . . . . . . . . . . . . . . . . 40V
Reference Output Current . . . . . . . . . . . . . . . Internally Limited
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
CONNECTION DIAGRAM
DIL-18, SOIC-18 (Top View)
N or J Package, DW Package
Unless otherwise indicated, voltages are referenced to ground.
Currents are positive into, negative out of specified terminal.
Consult Packaging Section of Databook for thermal limitations
and considerations of package.
DESCRIPTION (cont.)
When the output current is less than the fault level, the
external output transistor remains switched on. When the
output current exceeds the fault level, but is less than the
maximum sourcing level programmed by IMAX, the out-
put remains switched on, and the fault timer starts to
charge C
T
, a timing capacitor. Once C
T
charges to 2.5V,
the output device is turned off and C
T
is slowly dis-
charged. Once C
T
is discharged to 0.5V, the IC performs
a retry and the output transistor is switched on again.
The UC3914 offers two distinct reset modes. In one
mode with LR left floating or held low, the IC will repeat-
edly try to reset itself if a fault occurs as described
above. In the second mode with LR held high, once a
fault occurs, the output is latched off until either LR is
toggled low, the part is shutdown then re-enabled using
SD, or the power to the part is turned off and then on
again.
This part is offered in both 18 pin DW Wide-Body (SOIC)
and Dual-In-Line (DIL) packages.
ELECTRICAL CHARACTERISTICS:
Unless otherwise specified, T
A
= 0°C to 70°C for the UC3914, –40°C to 85°C for
the UC2914, and –55°C to 125°C for the UC1914. VCC = 12V, V
PUMP
= V
PUMP
(max), SD = 5V, CP1 = CP2 = C
PUMP
= 0.01µF.
T
A
= T
J
.
PARAMETER
VCC Section
I
CC
Shutdown I
CC
UVLO
UVLO Hysteresis
Fault Timing Section
Overcurrent Threshold
IMAX Input Bias
CT Charge Current
CT Discharge Current
CT Charge Current
CT Fault Threshold
CT Reset Threshold
Output Duty Cycle
Fault condition, I
PL
= 0
CT = 1V
CT = 1V
CT = 1V, Overload condition
–140
2.0
–6.0
2.25
0.45
1.5
T
J
= 25°C, with respect to VCC
Over operating temperature, with respect to VCC
–55
–57
–50
–50
1
–100
3.0
–3.0
2.50
0.50
3.0
–45
–42
3
–60
4.5
–1.5
2.75
0.55
4.5
mV
mV
µA
µA
µA
mA
V
V
%
(Note 2)
VCC = 35V, (Note 2)
SD = 0V
Turn on threshold
100
8
12
500
4.0
200
15
20
900
4.4
350
mA
mA
µA
V
mV
TEST CONDITIONS
MIN
TYP
MAX UNITS
2
TI [ TEXAS INSTRUMENTS ]
