MCP1601 Eval. Board User Guide
DS51315A-page 4
2003 Microchip Technology Inc.
1.2
DETAILED DESCRIPTION
The MCP1601 is a 500 mA Synchronous BUCK Regulator. Both the high-side BUCK
P-Channel and the low-side N-Channel switches are integrated within the device. The
integrated synchronous switch makes the MCP1601 very efficient, even when convert-
ing unregulated input voltages to low voltage fixed outputs. This evaluation board is
designed for a wide range of output voltages and currents. For specific applications,
smaller inductors, shielded inductors, tantalum capacitors and different output voltage
settings can improve the total DC/DC converter performance and cost.
The MCP1601 device can operate in three different modes of operation to optimize the
efficiency of the voltage conversion. The three operating modes are:
• Automatic switching from PFM Mode to PWM mode and back
• Synchronization to external Oscillator
• Fixed Frequency Forced PWM Mode
The MCP1601 output voltage is adjustable and is set by two external divider resistors.
A two-position switch is used on the MCP1601 Evaluation Board to change the resis-
tance of the external divider and adjust the output voltage to four different settings.
These output voltage settings are: 1.8V, 2.05V, 2.45V and 3.28V.
1.2.1
Applying Power to the Board
Two surface mount test points are used to apply power to the MCP1601 Evaluation
Board. For proper operation, the input voltage range is 2.7V < +V
IN
< +5.5V for all oper-
ating conditions. The MCP1601 has an internal Under-Voltage Lockout (UVLO) which
will prevent the board from operating when the input voltage is below the specified 2.7V
minimum.
1. Connect the positive side of the external power supply (+) to the +V
IN
test point.
2. Connect the negative side (GND) of the external power supply to the P
GND
test
point which is located directly below the +V
IN
test point.
1.2.2
Connecting a Load to the Board
To connect an external load to the board, the +V
OUT
and P
GND
test points are used.
• Connect the positive side of the load to the +V
OUT
pin and the negative or ground
side of the load to the P
GND
test point located directly under the +V
OUT
test point.
The MCP1601 output is rated for 500 mA (maximum) continuous current. The out-
put is protected against over current and short circuit conditions.
1.2.3
Enabling the MCP1601 - Using Switch U
3
, Position 1
Switch U
3
, position 1 is used to determine the SHDN mode for the MCP1601 device.
With switch U
3
, position 1 pushed to the right, the SHDN pin is pulled up and the output
of the MCP1601 device is enabled. When switch U
3
, position 1 is to the left, the
MCP1601 device is in a low quiescent current SHDN mode and the output is disabled.
