UCD3138064ARGCR datasheet(42/83 Pages) TI1

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Vdd

I BIAS

To ADC Mux

On/Off Control

AD00,

AD01

Resistor to

set PMBus

Address

UCD3138064A

SLUSCA5A – DECEMBER 2015 – REVISED AUGUST 2016

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Detailed Description

The PMBus/I2C interface is designed to minimize the processor overhead required for interface. It can

automatically detect and acknowledge addresses. It handles start and stop conditions automatically, and

can clock stretch until the processor has time to poll the PMBus status. It will automatically receive and

send up to 4 bytes at a time. It can automatically verify and generate a PEC. This means that a write byte

command can be received by the processor with only one function call. There is no need for any interrupts

at all with this PMBus/I2C interface. If it is polled every few milliseconds, it will work perfectly.

The interface also supports automatic ACK of two independent addresses. If both PMBus/I2C interfaces

are used at the same time a total of 4 independent addresses can be automatically detected.

Example: PMBus Address Decode via ADC12 Reading

The user can allocate 2 pins of the 12-bit ADC input channels, AD_00 and AD_01, for PMBus address

decoding. At power-up the device applies IBIAS to each address detect pin and the voltage on that pin is

captured by the internal 12-bit ADC.

Figure 6-21. PMBUS Address Detection Method

PMBus/I2C address 0x7E is a reserved address and should not be used in a system using the UCD3138x.

This address is used for manufacturing test.

6.4.7.3

SPI

The SPI is a high-speed synchronous serial input/output port that allows a serial bit stream of programmed

length (1 to 16 bits) to be shifted into and out of the device at a programmed bit-transfer rate. The SPI is

normally used for communication between the UCD3138x and external peripherals. Typical applications

include an interface to external I/O or peripheral expansion via devices such as shift registers, display

drivers, SPI EPROMs and analog-to-digital converters. The SPI allows serial communication with other

SPI devices through a 3-pin or 4-pin mode interface.

UCD3138064ARGCR Folha de dados(PDF) 42 Page - Texas Instruments