UPD161401WSLASHP datasheet(39/126 Pages) RENESAS

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Data Sheet S15726EJ2V0DS

µµµµPD161401

5.6 Power Supply Circuit

5.6.1 Power supply circuit

The power supply circuit generates the voltage necessary for driving the LCD. The power circuit consists of a booster

circuit, voltage regulator circuit, and voltage follower circuit.

Power system control register 1 (R52) turns ON/OFF the transformer, reference voltage generator, voltage regulator

circuit (V regulator circuit), and voltage follower circuit (V/F circuit). Part of the internal power supply function and an

external power supply can be used in combination. Table 5

−−−−12 shows the functions controlled by the 4-bit data of

power system control register 1 (R52). Table 5

−−−−13 shows examples of combinations of the power circuit functions.

Table 5

−−−−12. Function of Each Bit of Power System Control Register

Status

Item

OP3

: Booster circuit control bit

OFF

OP2

: Reference voltage generator control bit

OFF

OP1

: Voltage regulator circuit (V regulator circuit) control bit

OFF

OP0

: Voltage follower circuit (V/F circuit) control bit

OFF

Table 5

−−−−13. Examples of Combinations (Reference Values)

Status

OP3

OP2

OP1

OP0

Booster

Circuit

Reference

voltage

V Regulator

Circuit

V/F

Circuit

External

Power Input

Booster

System Pins

<1> Only internal power supply is

used

ΟΟ

VDD2

Used

<2> External VOUT power supply

×Ο

VDD2, VOUT

Open

<3> Only V/F circuit is used

Ο×

VDD2,

AMPOUT

Used

<4> Only external power supply is

used

××

VDD2, VOUT,

VLCD,

VLC1 to VLC4

Open

Remarks 1. The “booster system pins” are the C1

+, C1− to C5+, C5− pins.

2. All the power circuits are turned OFF when the

µPD161401 serves as a slave (M,/S pin = L).

5.6.2 Booster circuit

The power supply circuit has an internal booster circuit that increases the LCD driver voltage two- to seven-fold.

Because this booster circuit uses the internal oscillator signals, either the oscillator must be operating or an external

display clock must be input to operate this circuit.

The booster circuit usually uses the C1

+, C1− to C5+, C5− pins and VDD2 pins. Keep the wiring impedance of these pins

as low as possible. The number of boosting steps for main duty display and sub-duty display is set as shown in Table

−−−−14 by the MBTn and SBTn flags of power system control register 4 (R55).

For the number of boosting steps and how to connect capacitors, refer to Figure 5

−−−−15.

UPD161401W/P Datasheet(PDF) 39 Page - Renesas Technology Corp

UPD161401W/P Datasheet(HTML) 39 Page - Renesas Technology Corp

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