IRDC3640
USER GUIDE FOR IR3640 EVALUATION BOARD
DESCRIPTION
An output over-current protection function is
implemented by sensing the voltage developed
across the on-resistance of the synchronous
rectifier MOSFET for optimum cost and
performance.
This user guide contains the schematic and bill
of materials for the IR3640 evaluation board.
The guide describes operation and use of the
evaluation board itself. Detailed application
information for IR3640 is available in the
IR3640 data sheet.
The IR3640 is a PWM controller for use in
high performance synchronous Buck DC/DC
applications. This is designed to drive a pair
of external NFETs using a programmable
switching frequency up to 1.5MHz in voltage
mode. It is housed in a in 20 Lead 3x4
MLPQ package.
Key features offered by the IR3640 include
programmable soft-start ramp, Power Good
,
thermal protection, over voltage and over
current protection, programmable switching
frequency, tracking input, enable input, input
under-voltage lockout for proper start-up,
and pre-bias start-up.
BOARD FEATURES
•
V
in
= +12V (13.2V Max)
•
V
cc
= +5V (5.5V Max)
•
V
out
= +1.8V @ 0- 25A
•
F
s
= 600kHz
•
L = 0.33uH
•
C
in
= 4x10uF (ceramic 1210) + 2x330uF (electrolytic)
•
C
out
= 10x47uF (ceramic 0805)
1
IRDC3640
CONNECTIONS and OPERATING INSTRUCTIONS
A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum 25A load should be
connected to VOUT+ and VOUT-. The connection diagram is shown in Fig. 1 and inputs and outputs of the
board are listed in Table I.
IR3640 has two input supplies, one for biasing (Vcc) and the other as input voltage (Vin). Separate supplies
should be applied to these inputs. Vcc input should be a well regulated 4.5V-5.5V supply and it would be
connected to Vcc+ and Vcc-.
Table I. Connections
Connection
VIN+
VIN-
Vcc+
Vcc-
VOUT+
VOUT-
Sync
PGood
Signal Name
V
in
(+12V)
Ground of V
in
Vcc input
Ground for Vcc input
V
out
(+1.8V)
Ground of Vout
Synchronous input
Power Good Signal
LAYOUT
The PCB is a 6-layer board. All of layers are 2 Oz. copper. The IR3640 and other components are
mounted on the top and bottom side of the board.
Power supply decoupling capacitors, the Bootstrap capacitor and feedback components are located
close to IR3640. The feedback resistors are connected to the output voltage at the point of regulation
and are located close to IR3640. To improve efficiency, the circuit board is designed to minimize the
length of the on-board power ground current path.
2
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
