Pmbus Addressing; Selection Of "Dual Sample And Hold" Channel; 8.14 Dual Sample And Hold - Texas Instruments UCD3138 Technical Reference Manual

Dual Sample and Hold

8.14 Dual Sample and Hold

The Dual Sample and Hold is primarily designed to support accurate measurement of electrical power in
AC/DC converters. Sampling of both current and voltage signal simultaneously will provide no delay in the
measurement sequence in order to increase the measurement precision. This feature can be turned on
via clearing of bit-8 through bit-10 in ADCCTRL register. It is worth noting that this mechanism can not
hold more than a single voltage at a time.
The operation and configuration of Dual sample and hold is as follows:
• Dual sample and hold provides simultaneous sampling of two ADC inputs. This is simply done by
sampling and holding one channel exactly at the time a second channel is sampled for conversion and
converting the sample and hold channel at a later event in the current measurement sequence.
• Channels 2, 1 and 0 are the ONLY channels with sample and hold capability. These channels can be
sampled simultaneously with certain other "converting channels".
• Only One "Dual sample and hold channel" can be selected per ADC sequence. Selection of this single
channel is controlled by bypass firmware controlled bits and shown in
one of the channels (0, 1 and 2) can be held for upcoming "Dual Sample Measurement".
BYPASS_EN[2]
1
1
0
308
ADC12 Overview
Figure 8-13. PMBus Addressing
Table 8-3. Selection of "Dual Sample and Hold" Channel
BYPASS_EN[1] BYPASS_EN[0]
1
0
1
Copyright © 2016, Texas Instruments Incorporated
Table
BYPASS_EN[2:0] value
in hex
0 0x6
1 0x5
1 0x3
SNIU028A – February 2016 – Revised April 2016
www.ti.com
8-3. In other words only
Selected Dual
Sample/Hold Channel
Channel 0
Channel 1
Channel 2
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