QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1317A-E
ACTIVE RESET ISOLATED DC/DC POWER CONVERTER
1
LT1952
DESCRIPTION
Demonstration circuit 1317A-E 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-E converts isolated 36V to 72V input
to 5V output and provides over 12A of output cur-
rent. The converter operates at 260kHz with the peak
efficiency greater than 94% at 8A load. The DC1317
can be easily modified to generate output voltages in
the range from 0.6V to 48V. The output currents are
limited by total output power of up to 150W.
The other available versions of DC1317A are:
DC1317A-A, 36-72Vin to 3.3V, 30A
DC1317A-B, 18-72Vin to 5V, 25A
DC1317A-C, 18-72Vin to 12V, 10A
DC1317A-D, 18-72Vin to 24V, 5A
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 pre-
vents output voltage overshoot on startup or when
recovering 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
Table 1.
Performance Summary
PARAMETER CONDITION VALUE
Minimum Input Voltage I
OUT
= 0A to 12A 36V
Maximum Input Voltage I
OUT
= 0A to 12A 72V
V
OUT
V
IN
= 36V to 72V, I
OUT
= 0A to 12A 5V ±3%
Typical Output Ripple V
OUT
V
IN
= 36V to 72V, I
OUT
= 0A to 12A 50mV
P–P
Nominal Switching Frequency 260kHz
QUICK START PROCEDURE
Demonstration circuit 1317 is easy to set up to
evaluate the performance of LT1952 circuit. Refer
to Figure 1 for proper measurement equipment
setup and follow the procedure below:
NOTE:
When measuring the input or output volt-
age ripple, care must be taken to avoid a long ground
lead on the oscilloscope probe. Measure the input or
output voltage ripple by touching the probe tip di-
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1317A-E
ACTIVE RESET ISOLATED DC/DC POWER CONVERTER
2
rectly across the Vin or Vout and GND terminals.
See Figure 2. for proper scope probe technique.
1.
With power off, connect the input power supply to
Vin and GND. Make sure that the input power
supply has sufficient current rating at minimum
input voltage for the required output load.
2.
Turn on the power at the input.
NOTE:
Make sure that the input voltage does not
exceed 72V.
3.
Check for the proper output voltage.
Vout = 5V.
If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
4.
Once the proper output voltage is established, ad-
just the load within the operating range and ob-
serve the output voltage regulation, ripple voltage,
efficiency and other parameters.
5.
The DC1317 is equipped with an output capacitor
CSYS (470uF) that approximates typical system
rail capacitance. If system board already has ca-
pacitance of similar value CSYS can be removed.
Figure 1. Proper Measurement Equipment Setup