Analog Devices Linear Technology DC1757B Demo Manual

Description
Demonstration circuit 1757B is a high efficiency syn-
chronous buck-boost DC/DC converter with a 6V to 36V
input voltage range. It can supply a 12A maximum load
current with a 12V output. The demo board features the
LTC 3789EGN controller. The constant frequency current
®
mode architecture allows a phase-lockable frequency of up
to 600kHz, while an optional output current feedback loop
provides support for applications such as battery charging.
With a wide input range, wide output range and seamless
transfers between operation modes, the LTC3789 is ideal
for automotive, telecom, distributed DC power systems
and battery-powered applications.
performance summary
PARAMETER
Input Voltage Range
Output Voltage, V
OUT
Maximum Output Current, I
OUT
Typical Output Ripple
Typical Efficiency
Typical Switching Frequency
Quick start proceDure
Demonstration circuit 1757B is easy to set up to evaluate
the performance of the LTC3789. Refer to Figure 1 for
the proper measurement equipment setup and follow the
procedure below:
1. With power off, connect the input power supply to V
(6V to 36V) and GND (input return).
2. Connect the 12V output load between V
(Initial load: no load).
DEMO MANUAL DC1757B
12V/12A Buck-Boost Converter
The light load operation mode of the converter is deter-
mined with the MODE/PLLIN pin. Use JP2 jumper to select
pulse-skipping mode or forced continuous mode (CCM)
operation. The switching frequency is pre-set at about
200kHz. The converter can also be externally synchronized
to an external clock through the MODE/PLLIN pin (PLLIN
terminal on the board). To shut down the converter, force
the RUN pin below 1.2V (JP1: OFF). The power good
output (PGOOD terminal) is low when the output voltage
is outside of the ±10% regulation window.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1757B
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
(T = 25°C)
A
CONDITIONS
V = 6V to 36V, I = 0A to 12A
IN OUT
V = 6V to 36V, V = 12V
IN OUT
V = 36V, I = 12A (20MHz BW)
IN OUT
V = 12V, V = 12V, I = 12A
IN OUT OUT
3. Connect the DVMs to the input and outputs.
4. Turn on the input power supply and check for the proper
5. Once the proper output voltages are established, ad-
IN
and GND
OUT
High Efficiency
VALUE
6V to 36V
12V ±2%
12A
109mV
97.9%
200kHz
output voltages. V should be 12V ±2%.
OUT
just the loads within the operating range and observe
the output voltage regulation, ripple voltage and other
parameters.
LTC3789EGN
P–P
dc1757bf
1