Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - power management - special purpose 5.5 mA VQFN 48 (7x7)

PRODUCTPREVIEW

VIN

10uF

VCOM_PWR

4.7uF

To panel back -plane

(-0.5 to -5.0V, 15mA)

From Input Supply

(3.0V-6.0V)

4.7uF

VREF

AGND1

DAC

VCOM

VCOM[8:0]

VCOM_CTRL

4.7uF

From uC

VREF

4.7uF

INT_LDO

From VN (-17V)

TPS65186

www.ti.com

SLVSB04 –JULY 2011

V3P3 POWER SWITCH

The integrated power switch is used to cut the 3.3-V supply to the EPD panel and is controlled through the

V3P3_EN pin of the ENABLE register. In SLEEP mode the switch is automatically turned off and its output is

discharged to ground. The default power-up state is OFF. To turn the switch ON, set the V3P3_ENbit to 1.

VCOM ADJUSTMENT

VCOM is the output of a power-amplifier with an output voltage range of 0 V to -5.11 V, adjustable in 10-mV

steps. In a typical application VCOM is connected to the VCOM terminal of the EPD panel and the amplifier is

controlled through the VCOM_CTRL pin. With VCOM_CTRL high, the amplifier drives the VCOM pin to the

voltage specified by the VCOM1 and VCOM2 register.

For ease of design, the VCOM_CTRL pin may also be tied to the battery or IO supply. In this case, VCOM is

enabled with STROBE4 during the power-up sequence and disabled on STROBE1 of the power-down sequence.

Therefore VCOM is the last rail to be enabled and the first to be disabled.

KICK-BACK VOLTAGE MEASUREMENT

TPS65186 can perform a voltage measurement on the VCOM pin to determine the kick-back voltage of the

panel. This allows in-system calibration of VCOM. To perform a kick-back voltage measurement, follow these

steps:

• Pull the WAKEUP pin and the PWRUP pin high to enable all output rails.

• Set the HiZ bit in the VCOM2 register. This puts the VCOM pin in a high-impedance state.

• Drive the panel with the Null waveform. Refer to E-Ink specification for detail.

• Set the ACQ bit in the VCOM2 register to 1. This starts the measurement routine.

• When the measurement is complete, the ACQC (Acquisition Complete) bit in the INT1 register is set and the

nINT pin is pulled low.

• The measurement result is stored in the VCOM[8:0] bits of the VCOM1 and VCOM2 register.

Please note that the measurement result is not automatically programmed into non-volatile memory. Changing

the power-up default is described in the following paragraph.

STORING THE VCOM POWER-UP DEFAULT VALUE IN MEMORY

The power-up default value of VCOM can be user-set and programmed into non-volatile memory. To do so, write

the default value to the VCOM[8:0] bits of the VCOM1 and VCOM2 register, then set the PROG bit in VCOM2

such that it becomes the new power-up default. Once programming is complete, the PRGC bit in the INT1

VCOM[8:0] bits to 0x000h, then pull the WAKEUP pin low. After the WAKEUP pin is pulled back high, read the

VCOM[8:0] bits to verify that the new default value is correct.

Figure 25. Block Diagram of VCOM Circuit