Linear 968A-D Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 968A-D
DESCRIPTION
Demonstration circuit 968A-D is isolated input to high
current output 1/8th Brick footprint converter featur-
ing the LT ® 1952 switching controller. The DC968-D
converts isolated 36V to 75V input to 28V output and
provides over 4A of output current. The converter op-
erates at 300kHz with efficiency up to 95%. With
proper amount of airflow, the DC968-D converter can
generate up to 5A of output current. The DC968 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 200W. The other
available versions of DC968A are:
DC968A-A 36-75Vin to 3.3V@30A
DC968A-B 18-36Vin to 5V@20A
DC968A-C 36-75Vin to 12V@12A
Also, the DC968 can be modified for other input volt-
ages like 8V-36V, 18V-75V, 44V-52V, and so on. The
wider input voltage range will decrease the converter
Performance Summary
Table 1.
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
V OUT
Typical Output Ripple V OUT
Nominal Switching Frequency
QUICK START PROCEDURE
Demonstration circuit 968 is easy to set up to evalu-
ate the performance of LT1952 circuit. Refer to Fig-
ure 1 for proper measurement equipment setup and
follow the procedure below:
NOTE: When measuring the input or output voltage
ripple, care must be taken to avoid a long ground lead
ISOLATED DC/DC POWER CONVERTER
efficiency. Therefore, narrow input voltage range will
be more desirable.
The DC968 circuit features soft-start which prevents
output voltage overshoot on startup or when recover-
ing from overload condition.
The DC968 has precise over-current protection circuit
that allows for continuous operation under short cir-
cuit 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 4A
I OUT = 0A to 4A
V IN = 36V to 72V, I OUT = 0A to 4A
V IN = 36V to 72V, I OUT = 0A to 4A
on the oscilloscope probe. Measure the input or out-
put voltage ripple by touching the probe tip directly
across the Vin or Vout and GND terminals. See Figure
2. for proper scope probe technique.
With power off, connect the input power supply to
1.
Vin and GND. Make sure that the input power sup-
LT1952
VALUE
36V
72V
28V ±3%
100mV P–P
300kHz
1