QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1286
48V OUTPUT BOOST CONVERTER
1
LTC3862EGN, LTC3862EGN-1
DESCRIPTION
Demonstration circuit 1286A is DC/DC boost converter
featuring the LTC
®
3862EGN constant frequency current
mode boost controller. The DC1286A-A operates over 5V
to 36V input and provides 2A-5A of output current at
48V output. The DC1286A-B operates over 8V to 36V
input and provides 3A-5A of output current at 48V out-
put. The 200kHz constant frequency operation results in
small and efficient circuit. The converter provides high
output voltage accuracy (typically ±3%) over wide load
range with no minimum load requirement.
The demonstration circuit can be easily modified to gen-
erate different output voltages. Please consult LTC fac-
tory for details.
The DC1286A has small circuit footprint. It is a high per-
formance and cost effective solution for Telecom, Auto-
motive and Power Over Ethernet applications.
Design files for this circuit board are available. Call
the LTC factory.
PowerPath is a trademark of Linear Technology Corporation
Table 1.
Performance Summary
PARAMETER
CONDITION
VALUE
Minimum Input Voltage
DC1286A-A
DC1286A-B
IOUT = 0A to 2A
5V
8V
Maximum Input Voltage
IOUT = 0A to 5A
36V
VOUT
VIN = 12V, IOUT = 3A
48V ±3%
Typical Output Ripple VOUT
VIN = 12V, IOUT = 4A
400mVP–P
Nominal Switching Frequency
200kHz
QUICK START PROCEDURE
Demonstration circuit 1286A is easy to set up to evalu-
ate the performance of the LTC3862. For proper meas-
urement equipment setup refer to Figure 1 and follow
the procedure below:
NOTE:
When measuring the input or output voltage rip-
ple, care must be taken to minimize the length of oscil-
loscope probe ground lead. Measure the input or output
voltage ripple by connecting the probe tip directly across
the VIN or VOUT and GND terminals as shown in
Figure 2.
1.
With power off, connect the input power supply to Vin
and GND.
2.
Check the Vcc Bias voltage-setting jumper JP5. Move
it into Vin position if required.
3.
Turn the input power source on and slowly increase
the input voltage. Be careful not to exceed 36V.
NOTE:
Make sure that the input voltage Vin does not
exceed 36V. If higher operating voltage is required,
power components with higher voltage ratings should
be used. Also, Jumper JP5 will have to be moved to
12V position.
4.
Check for the proper output voltage of 48V.
If there is no output, temporarily disconnect the load
to make sure that the load is not set too high.
