Linear Technology 1317 Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1317A-F
ACTIVE RESET ISOLATED 9-36V INPUT TO 3.3V @20A DC/DC POWER CONVERTER
DESCRIPTION
Demonstration circuit 1317A-F is isolated input to
high current output 1/8th Brick footprint converter
featuring the LT ® 1952 switching controller with Ac-
tive Reset circuit. The Active Reset circuit can im-
prove the efficiency in wide input voltage applica-
tions. Also, the Active Reset allows the implementa-
tion of self-driven synchronous secondary rectifiers
in some applications.
The DC1317A-F converts isolated 9V to 36V input to
3.3V output and provides over 22A of output current
depending on cooling. When determining the cooling
requirements the actual input voltage range and con-
tinuous maximum output current must be taken into
account. The converter operates at 200kHz with the
peak efficiency greater than 92%. The DC1317 can be
easily modified to generate output voltages in the
range from 0.6V to 48V. The output currents are lim-
ited by total output power of up to 150W.
The available versions of DC1317A are:
DC1317A-A, 34-75Vin to 3.3V, 35A
DC1317A-B, 18-72Vin to 5V, 25A
DC1317A-C, 18-72Vin to 12V, 8A-12A
Performance Summary
Table 1.
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
V OUT
Typical Output Ripple V OUT
Nominal Switching Frequency
Arrow.com.
Downloaded from
DC1317A-D, 18-72Vin to 24V, 5A
DC1317A-E, 36-72Vin to 5V, 12A
DC1317A-F, 9-36Vin to 3.3V, 20A
DC1317A-G, 9-36Vin to 12V, 5A
DC1317A-H, 9-36Vin to 48V, 1.5A
The DC1317 circuit features soft-start which prevents
output voltage overshoot on startup or when recover-
ing from overload condition.
The DC1317 has precise over-current protection cir-
cuit that allows for continuous operation under short
circuit conditions. The low power dissipation under
short circuit conditions insures high reliability even
during short circuits.
The LT1952 can be synchronized to an external clock
of up to 400kHz. Please refer to LT1952 data sheet for
design details and applications information.
Design files for this circuit board are available. Call
the LTC factory.
LT is a trademark of Linear Technology Corporation
CONDITION
I OUT = 0A to 22A
I OUT = 0A to 22A
V IN = 9V to 36V, I OUT = 0A to 22A
(27Amax)
V IN = 9V to 36V, I OUT = 0A to 22A
LT1952-1
VALUE
9V
36V
3.3V ±3%
50mV P–P
200kHz
1