HT45F43 datasheet(98/152 Pages) HOLTEK

98 / 152 page

LDO Function

The devices contain a low power voltage regulator implemented in CMOS technology. Using CMOS

technology ensures low voltage drop and low quiescent current. There are two fixed output voltages of

2.4V and 3.3V, which can be controlled by a specific register. The internal LDO output combined with

various options by register can provide a fixed voltage for the LCD bias voltage, the OPA reference

voltage, the ADC reference voltage and as a fixed power supply for external device.

LDO Control Register

Bit

76543210

Name

¾¾¾

VLOE

REN1

VRES

VSEL

LDOEN

R/W

¾¾¾

R/W

POR

¾¾¾

00000

Bit 7~5

unimplemented, read as

²0²

Bit 4

VLOE: LDO output voltage control bit

0: disable

1: enable

If the VLOE and LDOEN are set to

²1², the LDO will output 2.4V or 3.3V to pin and disable

I/O function.

Bit 3

REN1: Bias voltage divided resistor control bit

0: disable

1: enable

If the REN1is set to

²1², that will turn on the resistor DC path, which will generate bias voltage

for OPAs or LCD SCOM.

Bit 2

VRES: Divided resistor voltage supply selection bit

0: VDD

1: VLDO

Bit 1

VSEL: LDO output voltage selection bit

0: 2.4V

1: 3.3V

Bit 0

LDOEN: LDO control bit

0: disable

1: enable

Note: 1. The total resistance of the divided resistor, 500K or 200K, can be selected by the ISEL flag in LCDC

2. To disable the LDO function will turn off the BUF1 as well, no matter the LDO output voltage control bit,

VLOE, is enabled or not.

3. If the LCD COM1 is enabled, COM1EN=1, then the VLOE flag will be forced to

²0² by hardware to disable

the LDO output ,in order to avoid the conflict with LCD COM1 bias voltage output.

4. If the LDO output is as the ADC reference voltage, then the VCAP should be connected a 0.1u capacitor to

ground.

5. If the LCDBUF is enabled, then the BUF2 will be turned on and the SW7 will be turned off.

6. If the LDO is disabled, LDOEN=0, then the SW4 will be turned to VDD, no matter VRES flag is

²1² or not.

Rev. 1.20

September 15, 2011

HT45F23/HT45F43

8-Bit Flash MCU with Op Amps & Comparators

HT45F43 датащи(PDF) 98 Page - Holtek Semiconductor Inc

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