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PAC1921

HIGH-SIDE CURRENT/POWER SENSOR

EVALUATION BOARD USER’S GUIDE

 2015 Microchip Technology Inc.

DS50002376A-page 21

Chapter 3. Hardware Description

3.1

INTRODUCTION

The PAC1921 High-Side Current/Power Sensor Evaluation Board provides the means

to evaluate features, and to view and modify registers. There are two modes for using

the evaluation board:

• Demo mode: Monitors an on-board power source

• Sys mode: Monitors an external power source

LEDs indicate status information and test points are included to monitor system

voltages with a user-provided voltmeter or oscilloscope.

The PAC1921 device is an SMBus-compliant, high-side current/power monitor in a

10-pin, 3 mm x 3 mm DFN package. For details regarding the PAC1921 device, refer

to the “PAC1921 Data Sheet” (DS20005293).

3.1.1

Power Source

The board requires only one Universal Serial Bus (USB) connection to power the

board. USB bus voltage is provided to the on-board test power sources and the

USB-to-SMBus bridge. The evaluation board circuitry uses the on-board regulator to

regulate the +5V USB power to +3.3V.

3.2

USB-TO-SMBus BRIDGE

The USB-to-SMBus is based on the MCP2221 USB-to-I2C™ protocol converter, which

provides the interface between the USB and the SMBus. Power is sourced to the

microcontroller from the USB interface for device power and communication.

3.2.1

Direct SMBus Connect Option

It is also possible to connect an external SMBus master to the PAC1921 High-Side

Current/Power Sensor Evaluation Board. A few modifications to the board are

required, as explained below:

• Remove the jumpers on J13 and connect the SMBus master to the

SMBus_DATA, SMBus_CLK and #READ/INT pins, as well as an external supply

for +3.3V. Note that a return is also provided on this header for convenience

(GND).

• The +3.3V can be supplied by the SMBus bridge by leaving the +3.3V jumper in

place and retaining the USB connection.

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