DA6250.007

13 April, 2018

12 (24)

DETAILED DESCRIPTION

MAS6250 operating modes are controlled by ROSC, DIN and CTRL pins as follows.

Table 1. Operating modes

CONTROL INPUTS

OPERATING MODES

ROSC

DIN

CTRL

DC/DC

OSC

PIEZO

LED

FB FET

PIEZO DRIVE

MODE

VIN

LOW 2)

LOW 2)

OFF

OFF

OFF 4)

OFF

OFF

EXTERNAL

SHUTDOWN

VIN

LOW 2)

HIGH

ON

OFF

OFF 4)

ON

ON 5)

EXTERNAL

LED

VIN

HIGH 3)

LOW 2)

ON

OFF

ON 1)

OFF

OFF

EXTERNAL

PIEZO

VIN

HIGH 3)

HIGH

ON

OFF

ON 1)

ON

OFF

EXTERNAL

PIEZO+LED

ROSC 6)

LOW 2)

LOW 2)

OFF

OFF

OFF 4)

OFF

OFF

SELF

SHUTDOWN

ROSC 6)

LOW 2)

HIGH

ON

OFF

OFF 4)

ON

ON 5)

SELF

LED

ROSC 6)

HIGH

LOW 2)

ON

ON

ON

OFF

OFF

SELF

PIEZO

ROSC 6)

HIGH

HIGH

ON

ON

ON

ON

OFF

SELF

PIEZO+LED

Note 1: In external drive mode the piezo outputs are enabled after two rising edges appeared at DIN

Note 2: For DIN and CTRL

“LOW” means being low at least max 15ms

Note 3: For DIN the “HIGH” corresponds to logic high level or pulsed signal at minimum 200Hz frequency

Note 4: Piezo

“OFF” is disable mode in which both piezo outputs are pulled to ground (VOP=VON=GND)

Note 5: Feedback switch between FB and ILED is activated when only LED is driven

Note 6: SELF drive mode selected by connecting frequency adjustment resistor from ROSC pin to GND.

Both DIN and CTRL pins have internal pull-down by 400k

Ω which is disabled to save current when the inputs are

pulled high. When selecting DIN=CTRL=GND the device is in shutdown mode and consumes only very small

leakage current.

The ROSC pin state selects between external drive and self-drive modes. In external drive mode (ROSC=VIN)

the internal oscillator is always disabled (off). In self-drive mode (frequency adjustment resistor connected from

ROSC pin to GND) the oscillator is enabled (on) when the DIN is set high.

In external drive mode (ROSC=VIN) the DIN pin can be used to control boost DC/DC converter on (DIN=HIGH)

and off (DIN=GND) while keeping driver outputs (VOP, VON) disabled. When disabled the driver outputs are at

GND state. The DC/DC converter is turned on by setting DIN=HIGH. By setting DIN=LOW turns off the DC/DC

converter after max 15 ms shutdown delay. This is useful operating mode when using MAS6250 just as DC/DC

power supply (see figure 12).

To drive piezo in external drive mode (ROSC=VIN) pulses need to be applied to the DIN pin at the desired signal

frequency. The rising edge of the first DIN pulse turns on the DC/DC converter but the piezo driver outputs (VOP,

VON) are enabled only at rising edge of the second DIN pulse as illustrated in figure 13. The piezo driver outputs

are disabled and DC/DC converter is turned off after keeping DIN=LOW for typ 10ms as illustrated in figure 14.

Again when new pulses are fed into DIN the charge pump and piezo driver will be enabled. In self-drive mode

(ROSC=VIN) the internal oscillator will provide the necessary pulses to enable piezo driver outputs and drive

audio frequency signal to the piezo.