DA6240C.000
1 November, 2010
MAS6240C
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 output voltage is
same to the input voltage, 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 Table 1 on 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 using
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 at low mostly for 50ms. 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 15ms
typically) all functional blocks are switched off to
achieve the quiescent current less than 1µA.
Two QFN packaged device versions are available. C1
version has short circuit protection which limits input
current taken from the supplies. It is suitable for
driving piezo in single ended configuration. C2 version
does not have input current limitation but it provides
maximum output current drive capability and loudest
sound pressure level. It is suited for driving piezo in
both single ended and differential configurations. In
the die form version D1 the input current limitation is
selectable by bonding.
FEATURES
Piezo Driver & Charge Pump
•
Thin 0.75 mm QFN 12 package
•
Three-Step Volume Adjusting
•
Both Single Ended and Differential Output
•
Up to 18Vpp Output from 3V Supply
•
One Wire Audio & Shutdown Control
•
Low External Part Count
•
Solution without Inductor
•
1 MHz Switching Frequency
•
Multi-Mode Charge Pump (1x/2x/3x)
APPLICATIONS
•
Wrist Watches
•
Alarm Clocks
•
Handheld GPS devices
•
PDAs
•
Portable Device with Sound Feature
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MAS [ MICRO ANALOG SYSTEMS ]
