Detailed Description

The MAX11041/MAX11042 wired remote controllers

recognize either six or 30 different keypresses consist-

ing of a resistor/switch array over a single connector.

Designed for wired remote controllers on the head-

phone or headset cord, the MAX11041/MAX11042

contain debouncing circuitry and jack insertion/

removal detection. During a keypress, the MAX11041/

MAX11042 store the key type and key duration in an 8-

word FIFO and INT (interrupt output) goes low. The

interface.

FORCE and SENSE

located in the remote controller connects SENSE to

ground (Figure 2). This event changes the impedance

seen by the SENSE line. The MAX11041/MAX11042

decode this resistor value to an 8-bit result (see the

Required Resistor Set section). FORCE and SENSE are

±15kV ESD (IEC 61000-4-2) protected.

Register Description

The MAX11041/MAX11042 contain one 8-bit control

register, an 8-word FIFO (each word consists of an 8-

bit key value and an 8-bit duration value), and an 8-bit

chip ID.

Chip ID

The chip ID identifies the features and capabilities of the

wired remote controller to the software. For the

MAX11041, the chip ID is 0x00. For the MAX11042, the

chip ID is 0x01.

Control Register

The MAX11041/MAX11042 contain one control register

(see Table 1). Bits C7, C6, and C5 control software shut-

down. Set FORCE high-impedance and indicate if the

FIFO is empty. Write/read to the control register through

Interface section).

FIFO

The MAX11041/MAX11042 contain an 8-word FIFO that

can hold enough information for four keypresses and

releases. Each keypress and release results in two data

words being stored into the FIFO. Each FIFO word con-

sists of 2 bytes. The 1st byte is the decoded keypress or

release (K7–K0) and the 2nd byte is the keypress or

release duration time. Table 2 shows the format of a key-

compatible serial interface (see the Digital Serial

Interface section). At power-up, all the FIFO is reset such

that K7–K0 are set to 0xFF hex and 0x0F, and T6–T0 are

set to 0x00. See the Applications Information section for

an example of how data is entered into the FIFO.

Wired Remote Controllers

6

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Pin Description

PIN

TQFN

UCSP

NAME

FUNCTION

1

D1

GND

Ground

2

C1

SENSE

Voltage Sense Input. Connect SENSE to FORCE through an external lowpass filter

IEC61000-4-2 ESD protection on SENSE.

3, 11

B1, D3

capacitor to GND.

4

A1

N.C.

5A2

A1

6A3

A0

7

A4

SHDN

Active-Low Shutdown Input. Bring

SHDN low to put the MAX11041/MAX11042 in shutdown

mode. FORCE is in a high-impedance state while

SHDN is low.

8

B4

SCL

9

C4

SDA

10

D4

INT

Active-Low Interrupt Output.

INT goes low when a valid keypress is detected at SENSE.

12

D2

FORCE

Force Output. Connect FORCE to the external resistor array. Connect SENSE to FORCE

is a ±15kV IEC61000-4-2 ESD protection on FORCE.

EP

—

EP

Exposed Pad. Connect EP to GND.