MAXIM MAX11041 Technical data

General Description

The MAX11041 wired remote controller converts up to
30 different pushbuttons into an I2C register. Together
with low-cost pushbutton switches and 1% resistors,
the MAX11041 is a total solution over a single-wire
interface. A wired remote controller easily piggybacks
to a standard 3.5mm headphone jack using a fourth
contact or one of the audio signals.

To conserve battery life, the MAX11041 consumes only
5µA (typ) while reading keypresses in real time without
microprocessor (µP) polling. The device sends the
debounced keypress along with key duration to the
application processor over the I2C interface. An 8-word
FIFO buffer records up to four keypress events to allow
plenty of time for the application processor to respond
to the MAX11041.

The MAX11041 includes ±15kV ESD protection devices
on the FORCE and SENSE inputs to ensure IEC 61000-4-2
compliance without any external ESD devices.

The MAX11041 is available in a 12-pin TQFN package.
The device is specified over the extended temperature
range (-40°C to +85°C).

Applications

Features

o Detect Up to 30 Different Keys and Jack

Insertion/Removal

o Works with Either 32Ω or 16Ω Headphones

o Adds Remote-Control Functionality to Devices

Using a Simple Resistor and Switch Array

o Low-Power Operation Consuming a Supply

Current of Only 5µA (typ)

o Works with Standard 2.5mm or 3.5mm 4-Pin

Headphone Jacks

o Supports Hold Function to Lockout Keys

o 100kHz/400kHz I2C Interface

o Single 1.6V to 3.6V Supply Voltage Range

o ±15kV ESD Protection (IEC 61000-4-2)

MAX11041

Wired Remote Controller

________________________________________________________________

Maxim Integrated Products

1

19-3984; Rev 3; 1/10

For pricing delivery, and ordering information please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

Pin Configuration

Ordering Information

*

EP = Exposed pad.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

Multimedia Controls for
Multimedia-Enabled
Cell Phones

Keyboard Encoder for
Slider, Flip, and other
Cell Phones

Portable Media Players

MP3, CD, DVD Players

PDAs

Digital Still Cameras

PDA Accessory
Keyboards

Multimedia Desktop
Speakers

Portable Game
Consoles

PART TEMP RANGE PIN-PACKAGE

MAX11041ETC+ -40°C to +85°C 12 TQFN-EP*

TOP VIEW

INT

V

FORCE

SDA

987

10

11

DD

12

EXPOSED PAD CONNECTED TO GND.

MAX11041

+

12

GND

THIN QFN

(4mm x 4mm x 0.6mm)

SCL

SENSE

3

SHDN

DD

V

A0

6

5

A1

N.C.

4

MAX11041

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VDDto GND...........................................................-0.3V to +4.0V

INT to GND.................................................-0.3V to (V

DD

+ 0.3V)

SCL, SDA, A1, A0, SHDN to GND.........................-0.3V to +4.0V

FORCE, SENSE to GND.........................................................±6V

Current into Any Pin..........................................................±50mA

Maximum ESD per IEC 61000-4-2

Human Body Model, FORCE, SENSE............................±15kV

FORCE, SENSE Short to GND....................................Continuous

Junction Temperature......................................................+150°C

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Soldering Temperature (reflow) .......................................+260°C

ELECTRICAL CHARACTERISTICS

(VDD= +1.6V to 3.6V, C

SENSE

= 10nF, R

SENSE

= 10kΩ, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

Wired Remote Controller

2 _______________________________________________________________________________________

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

KEY DETECTION CHARACTERISTICS

Detectable Keys

Maximum Switch Resistance (Note 1) 100 Ω

Maximum Switch Bounce Time (Note 1) 13 ms

External Resistor Tolerance (Note 1) ±1 %

SWITCH DEBOUNCE

Debounce Analog Time Constant

Chatter Rejection Pulses shorter than this are ignored 18 ms

Rising Voltage Debounce Time t

CPW

Provided the keys meet the next three
specifications; R
recommended circuit

C

= 10nF, external resistor from

SENSE

FORCE to SENSE is 10kΩ (R

Time required for a new voltage (due to
keypress) to be detected and stored in
FIFO

connected; use

JACK

SENSE

)

30 Keys

0.4 ms

18 ms

Falling Voltage Debounce Time t

Jack Insertion Debounce Time (Note 2) 18 ms

Jack Removal Debounce Time (Note 2) 18 ms

DURATION COUNTER

Duration-Counter Resolution One tick 32 ms

Duration-Counter Range MSB is overflow bit 0 127 Counts

Duration-Counter Accuracy ±20 %

DIGITAL INPUTS (SDA, SCL, SHDN, A0, A1)

Input High Voltage V

Input Low Voltage V

Input Leakage Current IIH, I

Input Hysteresis 9%V

Input Capacitance 10 pF

LPWS

Time required for detection of key release
and final time duration to be stored in FIFO

IH

IL

IL

18 ms

0.7 x
V

DD

0.3 x
V

DD

-10 +10 µA

V

V

DD

MAX11041

Wired Remote Controller

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +1.6V to 3.6V, C

SENSE

= 10nF, R

SENSE

= 10kΩ, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

____________________________________________________________________________________ 3

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DIGITAL OUTPUTS (SDA, INT)

Output High Voltage (INT)VOHI

Output Low Voltage (INT)V

Output High Leakage Current

Output Low Voltage (SDA) V

I2C TIMING CHARACTERISTICS (see Figure 1)

Serial Clock Frequency f

Bus Free Time Between STOP
and START Conditions

Hold Time (Repeated) START
Condition

SCL Pulse-Width Low t

SCL Pulse-Width High t

Setup Time for a Repeated
START Condition

Data Hold Time t

Data Setup Time t

SDA and SCL Receiving Rise
Time

SDA and SCL Receiving Fall
Time

SDA Transmitting Rise Time t

SDA Transmitting Fall Time t

Setup Time for STOP Condition t

Bus Capacitance C

Pulse Width of Suppressed Spike t

OLINTISINK

I

OHL

OLSDA

SCL

t

BUF

t

HD,STA

LOW

HIGH

t

SU,STA

HD,DAT

SU,DAT

t

RR

t

FR

RT

FT

SU,STO

b

SP

≤ 2mA

SOURCE

≤ 2mA

V

= V

OUT

DD

IOL = 3mA for VDD > 2V 0.4 V

IOL = 3mA for VDD < 2V

(Note 3)

(Note 3)

VDD = 3.6V (Note 3)

VDD = 2.4V to 3.6V

VDD = 1.6V to 2.4V

0.9 x
V

DD

0.1 x
V

DD

1µA

0.2 x
V

DD

0 400 kHz

1.3 µs

0.6 µs

1.3 µs

0.6 µs

0.6 µs

0 900 ns

100 ns

20 +

C

b

20 +

C

b

20 +

C

b

20 +

C

b

20 +
C

b

/ 10

/ 10

/ 10

/ 20

/ 20

300 ns

300 ns

250 ns

250

375

0.6 µs

400 pF

050ns

V

V

V

ns

MAX11041

Wired Remote Controller

4 _______________________________________________________________________________________

Note 1: Recommended properties of external switch for proper detection of 30 keys or key combinations.
Note 2: See the

Jack Insertion/Removal Detection

section.

Note 3: C

b

is the bus capacitance in pF.

Note 4: Key current depends on external key resistors and is calculated by V

DD

/ (30.1kΩ + RSW).

Figure 1. I2C Serial-Interface Timing

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +1.6V to 3.6V, C

SENSE

= 10nF, R

SENSE

= 10kΩ, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLIES

Power-Supply Voltage V

Average Operational Supply
Current

Shutdown Power-Supply Current I

Jack Current I

Key Current I
SHDN High to Part Active Wake-up time 5 ms

DD

I

DDOP

DDSHDN

DDJACK

DDBUTTON

1.6 3.6 V

Excluding jack/key current 5 20

Jack inserted, R

= 619kΩ 8

JACK

Excluding jack/key current 1 µA

Flowing when jack is inserted 4 µA

Flowing when keys pressed (Note 4) 90 µA

µA

START CONDITION

(S)

SDA

t

HD,STA

t

SU,DAT

SCL

t

HIGH

t

HD,DAT

REPEAT START CONDITION

(Sr)

t

SU,STA

t

RR

t

FR

t

LOW

t

HD,STA

t

RR,tRT

t

SU,STO

STOP CONDITION

t

FR,tFT

(P)

t

BUF

START CONDITION

(S)

MAX11041

Wired Remote Controller

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

____________________________________________________________________________________ 5

*

Oscilloscope shots are taken with simulated bounce and chatter. Real switches will exhibit different bounce and chatter characteristics.

DEBOUNCE SCOPE SHOT (FALLING)

MAX11041 TOC01

V

SENSE

10ms/div

µ

P READS FIFO

INT

DEBOUNCED KEY
ADDED TO FIFO

VDD SUPPLY CURRENT vs. VOLTAGE

7.0
NO JACK INSERTED

6.5

6.0

TA = +85°C

DEBOUNCE SCOPE SHOT (RISING)

V

SENSE

INT

DEBOUNCE KEY ADDED

TO FIFO

MAX11041 TOC04

KEYPRESS RELEASE SCOPE SHOT*

MAX11041 TOC02

V

SENSE

µ

10ms/div

P READS

FIFO

VDD SHUTDOWN SUPPLY CURRENT

1.00
NO JACK INSERTED

0.75

INT

DEBOUNCE KEY ADDED

vs. VOLTAGE

TO FIFO

µ

10ms/div

MAX11041 TOC05

MAX11041 TOC03

P READS

FIFO

(µA)

5.5

DD

I

5.0

4.5

4.0

TA = +25°C

TA = -40°C

1.6 2.62.1 3.1 3.6
VDD (V)

(µA)

0.50

DD

I

0.25

0

1.6 2.62.1 3.1 3.6

TA = +85°C

TA = -40°C

TA = +25°C

VDD (V)

MAX11041

Detailed Description

The MAX11041 wired remote controller recognizes 30 dif­ferent keypresses consisting of a resistor/switch array
over a single connector. Designed for wired remote con­trollers on the headphone or headset cord, the
MAX11041 contains debouncing circuitry and jack inser­tion/removal detection. During a keypress, the MAX11041
stores the key type and key duration in an 8-word FIFO
and INT (interrupt output) goes low. The results stored in
the FIFO are accessed through the I

2

C interface.

FORCE and SENSE

During a keypress, a unique external resistor (R

SW_

)
located in the remote controller connects SENSE to
ground (Figure 2). This event changes the impedance
seen by the SENSE line. The MAX11041 decodes 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 contains 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.

Control Register

The MAX11041 contains one control register (see Table

1). Bits C7, C6, and C5 control software shutdown. Set
FORCE high-impedance and indicate if the FIFO is
empty. Write/read to the control register through the I

2

C-

compatible serial interface (see the

Digital Serial

Interface

section).

FIFO

The MAX11041 contains 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 consists 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 keypress
entry into the FIFO. Read the FIFO through the I2C-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 Controller

6 _______________________________________________________________________________________

Pin Description

PIN NAME FUNCTION

1 GND Ground

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

2 SENSE

3, 11 V

4 N.C. No Connection. Leave unconnected or connect to VDD.

5A1I

6A0I

7 SHDN

8 SCL I2C Serial-Interface Clock Input. SCL requires a pullup resistor.

9 SDA I2C Serial-Interface Data Input/Output. SDA requires a pullup resistor.

10 INT Active-Low Interrupt Output. INT goes low when a valid keypress is detected at SENSE.

12 FORCE

EP EP Exposed Pad. Connect EP to GND.

DD

and C
SENSE.

Power-Supply Input. Connect both VDD inputs together and bypass each VDD with a 0.1µF capacitor to
GND.

2

C Address Input 1. Logic state represents bit 1 of the I2C slave address.

2

C Address Input 0. Logic state represents bit 0 of the I2C slave address.

Active-Low Shutdown Input. Bring SHDN low to put the MAX11041 in shutdown mode. FORCE is in a
high-impedance state while SHDN is low.

Force Output. Connect FORCE to the external resistor array. Connect SENSE to FORCE through an
external lowpass filter composed of R
ESD protection on FORCE.

(see the FORCE and SENSE section). There is a ±15kV IEC 61000-4-2 ESD protection on

SENSE

= 10kΩ and C

SENSE

= 10nF. There is a ±15kV IEC 61000-4-2

SENSE

SENSE