PCA9546A datasheet(10/29 Pages) TI

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2C Interface Timing Requirements

Switching Characteristics

Interrupt and Reset Timing Requirements

PCA9546A

4-CHANNEL I2C AND SMBus SWITCH

WITH RESET FUNCTION

SCPS148E – OCTOBER 2005 – REVISED JANUARY 2008

over recommended operating free-air temperature range (unless otherwise noted) (see Figure 10)

STANDARD MODE

FAST MODE

I2C BUS

UNIT

MIN

MAX

MIN

MAX

fscl

I2C clock frequency

100

400

kHz

tsch

I2C clock high time

0.6

µs

tscl

I2C clock low time

4.7

1.3

µs

tsp

I2C spike time

tsds

I2C serial-data setup time

250

100

tsdh

I2C serial-data hold time

0(1)

µs

ticr

I2C input rise time

1000

20 + 0.1Cb

(2)

300

ticf

I2C input fall time

300

20 + 0.1Cb

(2)

300

tocf

I2C output fall time

10-pF to 400-pF bus

300

20 + 0.1Cb

(2)

300

tbuf

I2C bus free time between stop and start

4.7

1.3

µs

tsts

I2C start or repeated start condition setup

4.7

0.6

µs

tsth

I2C start or repeated start condition hold

0.6

µs

tsps

I2C stop condition setup

0.6

µs

tvdL(Data)

Valid-data time (high to low)(3)

SCL low to SDA output low valid

µs

tvdH(Data)

Valid-data time (low to high)(3)

SCL low to SDA output high valid

0.6

µs

ACK signal from SCL low

tvd(ack)

Valid-data time of ACK condition

µs

to SDA output low

I2C bus capacitive load

400

(1)

A device internally must provide a hold time of at least 300 ns for the SDA signal (referred to the VIH min of the SCL signal), in order to

bridge the undefined region of the falling edge of SCL.

(2)

Cb = total bus capacitance of one bus line in pF

(3)

Data taken using a 1-k

Ω pullup resistor and 50-pF load (see Figure 10)

over recommended operating free-air temperature range, CL ≤ 100 pF (unless otherwise noted) (see Figure 10)

FROM

PARAMETER

MIN

MAX

UNIT

(INPUT)

(OUTPUT)

RON = 20 Ω, CL = 15 pF

0.3

tpd

(1)

Propagation delay time

SDA or SCL

SDn or SCn

RON = 20 Ω, CL = 50 pF

(1)

The propagation delay is the calculated RC time constant of the typical ON-state resistance of the switch and the specified load

capacitance, when driven by an ideal voltage source (zero output impedance).

over recommended operating free-air temperature range (unless otherwise noted)

PARAMETER

MIN

MAX

UNIT

tWL

Pulse duration, RESET low

trst

(1)

RESET time (SDA clear)

500

tREC(STA)

Recovery time from RESET to start

(1)

trst is the propagation delay measured from the time the RESET pin is first asserted low to the time the SDA pin is asserted high,

signaling a stop condition. It must be a minimum of tWL.

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