PAC1941T-1ESLASH4MX. datasheet(23/96 Pages) MICROCHIP

23 / 96 page

 2021 Microchip Technology Inc.

DS20006543A-page 23

PAC194X

5.0

DEVICE OVERVIEW

A high-voltage multiplexer connects the input pins to

the VBUS and VSENSE amplifiers. The amplifier outputs

are sampled simultaneously for each channel, con-

verted by 16-bit ADCs and processed for gain and off-

set error correction. After each conversion, VBUS and

VSENSE are multiplied together to give VPOWER.

An internal oscillator and digital control signals control

the two ADCs and the MUX. The MUX sequentially

connects each channel’s amplifiers to the ADC inputs.

The

PAC1941-1,

PAC1942-1,

PAC1943-1

and

PAC1944-1 devices share a pin for the VBUS measure-

ment and the source-side voltage VSENSE+ across an

external current sense resistor, RSENSE. This enables

four input channels with eight pins. For PAC1941-2

and PAC1942-2, the chip allows VBUS+ and VBUS- to

go to separate pins for two channels, unconnected

from the VSENSE+ and VSENSE- pins. This enables the

low-side current measurement.

5.1

Initial Operation

After Power-on Reset and a start-up sequence, the

device is in the Active state and begins sampling the

inputs sequentially. Voltage and current are sampled

for all active channels and power is calculated and

accumulated. All active channels are sampled at

1024 SPS by default. Sample rates of 256, 64 or

8 SPS may be programmed over the I2C or SMBus. If

the SLOW pin is asserted, the sample rate is 8 SPS.

For sampling rates lower than 1024 SPS, the device is

in Sleep mode for a portion of the conversion cycle,

which results in lower power dissipation. If fewer than

four channels are active, power is also reduced.

To read accumulator data and reset the accumulators,

the REFRESH command is used. To read the voltage,

current, power and accumulator data without resetting

the accumulators, the REFRESH_V command is

used. Changes to the Control register (01h) are acti-

vated by sending any REFRESH command. When a

new value is written to the Control register (01h), the

new values take effect after the current round robin

cycle (actively sampling) or before the next round

robin sampling cycle following any REFRESH

command.

5.2

REFRESH Command

The host sends the REFRESH command after

changing the Control register and/or before reading

accumulator data from the device. The host controls

the accumulation period in this manner.

The readable registers for the VBUS, VSENSE, Power,

accumulator outputs and accumulator count are

updated by the REFRESH command and the values

are static until the next REFRESH command.

These readable registers will be stable within 1 ms

from sending the REFRESH command and may be

read by the host at any time up until the next

REFRESH command is sent.

Changes written to the Control and Configuration

registers take effect within 1 ms after a REFRESH

command is sent. Any new commands written within

this 1 ms window will be ignored and NACKed to

indicate that they are ignored.

The values for VBUS and VSENSE measurement results

and Power calculation results respond to the

REFRESH command in the same fashion as the

accumulators and accumulator count. The readable

registers will be stable within 1 ms from sending the

REFRESH command and may be read by the host at

any time. The internal values continue to be updated

according to the sampling plan determined by the

settings in the Control register. The results that are

sent to the readable registers for VBUS, VSENSE and

Power are the values from the most recent complete

conversion cycle. See Register 7-1.

5.3

REFRESH_G Command

The REFRESH_G command is identical in every

respect to the REFRESH command, but it is used with

the I2C General Call address (0000 000). This allows

the system to issue a REFRESH command to all of the

PAC194X devices in the system with a single

command. After the REFRESH_G command, the data

may be read device by device to capture a snapshot of

the system power and energy for all devices (see

can also be used with a valid client address, but in this

case, only the device with this client address will

receive the command. In other words, it has the same

properties as the REFRESH command with the

possibility of being compatible with the I2C General

Call address.

Note:

In Burst/Fast modes with one or more

channels disabled, the 1 ms REFRESH

delay will be 200 µs per channel, with an

additional 200 µs delay in Fast mode for

the calibration channel. The internal accu-

mulator values and accumulator count are

reset by the REFRESH command, but the

sampling of the inputs, data conversion

and power integration are not interrupted

and continue as determined by the

settings in the Control register.

PAC1941T-1E/4MX. Datasheet(PDF) 23 Page - Microchip Technology

PAC1941T-1E/4MX. Datasheet(HTML) 23 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96

Datasheet Download

Link URL