MCP1650/1/2/3 Evaluation Board User’s Guide

DS51462A-page 6

 2004 Microchip Technology Inc.

- The Under Voltage Lockout (UVLO) feature will prevent the MCP1651 from

starting the converter until the input voltage is above the minimum thresh-

old. Once the input voltage is raised above the UVLO threshold, the

converter will begin to boost the output voltage up to 5V. The output voltage

is fed back to the input so that, once the Boost converter has started, it can

run down to lower input voltages at reduced load currents.

2. Applying the load to the MCP1651 bootstrap application circuit:

- To apply a load to the MCP1651 application circuit, the positive side of the

_1 test point (TP2). The negative

side of the load should be connected to the GND test point (TP3). The

maximum load current should not exceed 1A while the input voltage is

within the range specified for this application (2.8V to 4.8V).

3. Using the shutdown feature of the MCP1651 application circuit:

- To shutdown the MCP1651, use a jumper wire to connect the SHDN test

point (TP5) to the GND test point (TP4). By grounding the shutdown pin, the

MCP1651 will enter the shutdown state and minimum quiescent current will

be drawn from the input source. To resume normal operation, remove the

jumper pin from the SHDN test point to ground and the MCP1651 will start.

4. Low Input Status LED:

- The MCP1651 has a low input voltage status indicator that will provide

visual indication (via a LED) when the input voltage is below 3V. This LED

will illuminate to provide a warning that the input voltage is approaching the

minimum 2.8V input voltage.

MCP1653S Application Circuit

1. Powering the MCP1653 non-bootstrap application circuit:

- Apply the input voltage to the surface-mount test points provided. The input

voltage source should be limited to the 3.0V to 3.6V range to regulate the

12V output. The input voltage must not exceed the +5.5V maximum rating

of the MCP165X. The source current necessary to regulate the output

voltage to +12V at 0.4A should be a minimum of approximately 3A.

(TP6). Connect the negative, or return side, (–) of the input source to the

- The UVLO feature will prevent the MCP1653 from starting the converter

until the input voltage is above the minimum threshold. Once the input

voltage is raised above the UVLO threshold, the converter will begin to

boost the output voltage up to 12V. To maintain regulation of the 12V output,

the input voltage range should be between 3.0V and 3.6V.

2. Applying the load to the MCP1653 non-bootstrap application circuit:

- To apply a load to the MCP1653 application circuit, the positive side of the

_2 test point (TP7). The negative

side of the load should be connected to the GND test point (TP10). The

maximum load current should not exceed 0.4A while the input voltage is

within the range specified for this application (3.0V to 3.6V).

3. Using the shutdown feature of the MC1653 application circuit:

- To shutdown the MCP1653, use a jumper wire to connect the SHDN test

point (TP9) to the GND test point (TP8). By grounding the shutdown pin, the

MCP1653 will enter the shutdown state and minimum quiescent current will

be drawn from the input source. To resume normal operation, remove the

jumper pin from the SHDN test point to ground and the MCP1653 will start.