AS39513 datasheet(91/108 Pages) AMSCO

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ams Datasheet

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[v1-10] 2018-Apr-25

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AS39513 − Detailed Description

SPI Commands

The AS39513 has a serial peripheral interface (SPI) bus that

enable full and unlimited EEPROM access. Its primary purpose

is production calibration and UID programming, but it could

also be used by an application to configure the chip during

device test.

The SPI bus uses four digital signals. Three of these signals are

inputs: CE (SPI chip enable), SCLK (SPI clock), and DIN (SPI data

input). One is an output: DOUT (SPI data output). The CE signal

enables the SPI interface when high. (When CE is low, the

DIN/DOUT pins are used by other application functions unless

the SPI direct command “Set IO Mode” has locked the device in

SPI mode). The CE input includes an RD=100k ohm pull down

to ground. If driven externally the CE pin should have a 1nF

capacitor connected to ground. The SCLK is used to control the

timing of the output data and determine when to capture the

input data. The maximum SCLK clock frequency fSLCK is 100kHz.

The SCLK input includes an RD= 100k ohm pull down to ground.

DIN data is captured on the falling edge of SCLK. DOUT data will

change on the rising edge of SCLK. The DIN input can be

configured to have an RD=100k ohm pull down to ground or

RU=30k ohm pull up resistor. See DIMD[1:0].

When CE is set high, a delay time is needed to allow the on-chip

high-speed clock and the digital supply regulators to wake up.

(If the device is locked in SPI mode through the “Set IO Mode”

direct command, this delay is much shorter since the

high-speed clock and regulators remain active.) The SPI

interface also needs to check that DOUT is low. If DOUT is high,

this is a busy signal that indicates that the interface is not ready

to receive SPI commands.

Once there has been sufficient delay and DOUT is low, the

command and any additional input data are clocked in, MSB

first, using SCLK and DIN. For commands with a response, the

DOUT pin will go high to indicate data is ready, and then SCLK

pulses are used to clock out the data on DOUT. For write

commands, DOUT pin acts as a memory busy indicator, going

high while the write is in progress.

Commands are not intended to be chained, that is, CE is

expected to go low after each command. If a command requires

additional processing time after CE goes low, such as an

EEPROM write, the processing continues and the regulators and

high-speed clock are not shut down until the command is

processed.

All SPI commands and data are grouped along 8-bit byte

boundaries. There are three types of commands: write

commands, read commands, and direct commands. The two

MSBs in the 8 or 16-bit command word selects the command

type. Each command type is described below.

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