Detailed Description

The MAX17841B allows any host controller with an SPI

port to communicate with one or more battery manage-

ment slave devices that use Maxim’s battery manage-

ment UART protocol.

Together with the host controller, the ASCI is the mas-

ter for communications with the slave devices. Figure 5

shows the functional block diagram. Table 1 shows how

power is distributed inside the device.

Serial Peripheral Interface (SPI)

The SPI port is a synchronous data link that the host uses

to read and write the ASCI registers and the UART com-

munication buffers.

SPI Transactions

An SPI transaction is initiated when the host drives the CS

pin low. The host always transmits data most-significant

bit (MSB) first to the ASCI. After the first byte, it can termi-

Pin Description (continued)

Table 1. Internal Power Distribution

Figure 5. Functional Diagram

PIN

NAME

FUNCTION

DESCRIPTION

15

RXN

Output

UARTReceiverNegativeInput.ConnecttoTxportnegativeoutputofUARTslavedevice

per application circuit.

16

RXP

Output

UART Receiver Positive Input. Connect to Tx port positive output of UART slave device per

application circuit.

BLOCK

SUPPLY

Oscillator

SPIPortandLDORegulator

DCIN

Digital,UART,andControl

DOUT

INT

RXN

RXP

TXP

TXN

GNDL

REGISTERS

CONTROLLER

DCIN

3.3V

SPI SLAVE

CONTROLLER

CS

SCLK

DIN

RECEIVE

BUFFER

UART

DECODER

DCIN

AGND

SHDN

RECEIVER

16MHz

OSCILLATOR

3.3V LDO

REGULATOR

TRANSMIT

BUFFER

MAX17841B

FILL BYTE

GENERATOR

UART

ENCODER

TRANSMITTER

Maxim Integrated │ 8

MAX17841B

Automotive SPI Communication Interface (ASCI)

www.maximintegrated.com