Octal SMBus-to-Parallel I/O Expanders

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5

500mV/div

V+

2V/div

PULLUP = 10k

Ω to V+

MAX1608

IO_ POWER-UP RESPONSE

Typical Operating Characteristics (continued)

IO_

2V/div

ALERT

5V/div

200ns/div

IO_ DRIVEN EXTERNALLY

ALERT DELAY

(IO_ FALLING)

NAME

FUNCTION

1– 8

IO0– IO7

Combined Input/Output. Open-drain output. Can withstand +28V.

9

GND

Ground

PIN

10, 11

ADD0, ADD1

SMBus Address Select. See Table 1.

12

SMBDATA

SMBus Serial-Data Input/Output. Open-drain output. Requires external pullup resistor.

16

V+

Supply Voltage Input, +2.7V to +5.5V. Bypass to GND with a 0.1µF capacitor.

15

SMBSUS

SMBus Suspend-Mode Control Input. The device enters the state previously stored in the

suspend-mode registers if low, or enter the state previously stored in the normal-mode reg-

isters if high.

14

SMBCLK

SMBus Serial Clock Input

13

ALERT

Active-Low Interrupt Output. Open-drain output. Requires external pullup resistor.

Pin Description

Detailed Description

The MAX1608/MAX1609 convert 2-wire SMBus serial

data into eight latched parallel outputs (IO0–IO7). These

devices are intended for general-purpose remote I/O

expansion. Each device has eight high-voltage open-

drain outputs that double as TTL-level logic inputs.

Typical applications range from high-side MOSFET load-

switch drivers in power-management systems, to push-

button switch monitors, to general-purpose digital I/Os.

The MAX1608/MAX1609 include two complete sets of

registers, each consisting of one output data register to

set the output states and two interrupt mask registers.

The SMBSUS line selects which set of registers control

the device state. The input register is used to perform

readback of the actual IO states.

The MAX1608/MAX1609 operate from a single +2.7V

to +5.5V supply with a typical quiescent current of

2.5µA, making them ideal for portable applications.

Additionally, the devices include an ALERT function to

alert the master of change of condition (Figure 1).