DA6240.001

20 November 2006

1 (10)

MAS6240

Piezo Driver with Multi-Mode Charge Pump

• Both Single Ended and

Differential Output

• Three-Step Volume Adjusting

• Up to 18Vpp Output from 3V

Supply

• One Wire Audio & Shutdown

Control

• High Efficiency

• Solution without Inductors

• Low External Part Count

DESCRIPTION

MAS6240 is a piezo driver device that can drive

outputs up to 18Vpp from 3V supply. An internal

three-mode charge pump generates boosted supply

voltage for piezo driver. For adjusting the piezo

element sound volume, the charge pump can

operate in either of a 1x, 2x or 3x mode. In 1x mode

the input voltage is bypassed to the output, in 2x or

3x mode the input voltage is boosted up accordingly

2 or 3 times. Charge pump mode is selected by

control pins EN1 and EN2 (see Table1 at page 2).

MAS6240 is an easy and low-cost solution for piezo

driver, since only 4 small value capacitors are

needed in addition to sound element - the use of

inductors can be avoided. The inductorless design

also causes significantly less disturbance to the

surrounding circuits making it an ideal choice for

sensitive designs. Its charge pump switches at

1MHz, allowing to use as small as 100nF external

capacitors.

Control logic is switching the charge pump on at

first rising signal of digital input (DIN) pin. The

switch-off signal will be generated while the signal at

DIN has been low at least for 10ms. The piezo

driver is enabled at a second rising edge of a pulse

at DIN and the signal is transferred to piezo output

VO1. The same signal is inverted into output VO2

for using differential output.

Continuous logic high level at DIN input causes the

charge pump to be turned ON but leaves the audio

amplifier disabled. In that state the charge pump

output can be used to power the external LEDs or

any other external circuit. The output voltage is still

selectable at three steps.

In "disabled" mode (DIN has been low for 10ms) all

functional blocks are switched off to achieve the

quiescent current less than 1µA.

See more information in the chapter Detailed

Description.

FEATURES

APPLICATIONS

Thin 0.75 mm QFN 12 package

Piezo Driver

•

Three-Step Volume Adjusting

•

Both Single Ended and Differential Output

•

Up to 18Vpp Output from 3V Supply

•

One Wire Audio & Shutdown Control

Charge Pump

•

Wrist Watches

•

Alarm Clocks

•

Handheld GPS devices

•

PDAs

•

Portable Device with Sound Feature

•

Low External Part Count

•

Solution without Inductors

•

1 MHz Switching Frequency

•

Multi-Mode Charge Pump (1x/2x/3x)

This is preliminary information on a new

product under development. Micro Analog

Systems Oy reserves the right to make any

changes without notice.