IR3898MPBF IRF [International Rectifier], IR3898MPBF Datasheet - Page 2

• Manufacturer Part Number: IR3898MPBF
• Description: USER GUIDE FOR IR3898 EVALUATION BOARD
• Manufacturer: IRF [International Rectifier]

CONNECTIONS and OPERATING INSTRUCTIONS
A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum of 6A load should be
connected to VOUT+ and VOUT-. The inputs and output connections of the board are listed in Table I.
IR3898 has only one input supply and internal LDO generates Vcc from Vin. If operation with external Vcc
is required, then R15 can be removed and external Vcc can be applied between Vcc+ and Vcc- pins. Vin pin
and Vcc/LDO_Out pins should be shorted together for external Vcc operation.
The output can track voltage at the Vp pin. For this purpose, Vref pin is to be connected to ground (use zero
ohm resistor for R21). The value of R14 and R28 can be selected to provide the desired tracking ratio
between output voltage and the tracking input.
LAYOUT
The PCB is a 4-layer board (2.23”x2”) using FR4 material. All layers use 2 Oz. copper. The PCB
thickness is 0.062”. The IR3898 and other major power components are mounted on the top side of the
board.
Power supply decoupling capacitors, the bootstrap capacitor and feedback components are located
close to IR3898. The feedback resistors are connected to the output at the point of regulation and are
located close to the SupIRBuck IC. To improve efficiency, the circuit board is designed to minimize the
length of the on-board power ground current path.
12/8/2011
VIN+
VIN-
Vout+
Vout-
Vcc+
Vcc-
Enable
PGood
AGnd
Connection
Table I. Connections
Vin (+12V)
Ground of Vin
Vout(+1.2V)
Ground for Vout
Vcc/ LDO_Out Pin
Ground for Vcc input
Enable
Power Good Signal
Analog ground
Signal Name
IRDC3898-P1V2
2