Linear Technology DC1940A Demo Manual

DESCRIPTION
Demonstration circuit 1940A is a low quiescent current,
synchronous buck converter featuring the LTC
This demo board converts a 16V to 60V voltage to a 12V
at 15A output.
The main features of this board include an internal LDO
for gate drive power from V
PGOOD pins, a mode selector that allows the converter
to run in constant current mode (CCM), pulse-skipping or
Burst Mode ® operation, and selectable current limit. The
DC1940A supports an adjustable output voltage, soft-start
and tracking. The wide input voltage range of 16V to 60V is
suitable for double battery automotive and distributed DC
power systems where low quiescent current is important.
The LTC3891 data sheet gives a complete description of
this part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 1940A.
The 60V avalanche rated MOSFETs, which are used
on DC1940A, can be operated at their rated voltage.
However, if application derating requirements are
stricter, MOSFETs with higher voltage rating can be used.
PERFORMANCE SUMMARY
PARAMETER
Minimum Input Supply Voltage
Maximum Input Supply Voltage
Output Voltage Range
Typical Switching Frequency
Typical Output Ripple (V , 12V)
OUT
Efficiency Typical (V , 12V)
OUT
Supply Quiescent Current
Supply Shutdown Current
® 3891EUDC.
or EXTV , RUN and
IN CC
(T = 25°C)
A
CONDITIONS
V = 16V to 60V, I = 0A to 5A
IN OUT1
I = 15A
LOAD
V = 24V; V = 12V, I
IN OUT O
V = 24V
IN
DEMO MANUAL DC1940A
Low Quiescent Current,
High Voltage Step-Down
Please note, MOSFETs with higher voltage ratings may af-
fect the efficiency. If 60V MOSFETs are used, the MOSFET
avalanche rating and testing is typically done with 30%
over voltage margin (78V for 60V rated MOSFET). Please
check with particular MOSFET manufacturer to ensure the
avalanche voltage rating.
The DC1940A supports the following MOSFET packages:
LFPAK, PowerPAK SO-8 and Power 56. The subsequent
logic level (SV gate) MOSFETs can be used with DC1940A.
Si7850DP
RJK0651DPB
HAT2266H
BSC100N06LS3 G
FDMS86520L
For synchronization to an external clock, remove jumper
JP2 and apply sync signal on terminal SYNC.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
= 0A, Burst Mode Operation
Converter
Vishay
Renesas
Renesas
Infineon
Fairchild
VALUE UNITS
16
60
12 ± 2%
125
80
97
50.8
14.7
dc1940af
V
V
V
kHz
mV
%
μA
μA
1