Epson S1C63558 2.1 Power Supply, 2.1.1 Voltage <VD1> for oscillation circuit and internal circuits, 2.1.2 Voltage <VC1–VC5>for LCD driving, EPSON

CHAPTER 2: POWER SUPPLY AND INITIAL RESETCHAPTER 2 POWER SUPPLY AND INITIAL RESET

2.1 Power Supply

The S1C63558 operating power voltage is as follows:Supply voltage VDD = 2.2 V to 5.5 V

The S1C63558 operates by applying a single power supply within the above range between VDD and VSS. The S1C63558 itself generates the voltage necessary for all the internal circuits by the built-in power supply circuits shown in Table 2.1.1.

Table 2.1.1 Power supply circuits

Circuit	Power supply circuit	Output voltage
Oscillation and internal circuits	Oscillation system voltage regulator	VD1
LCD driver	LCD system voltage circuit	VC1–VC5
FSK demodulator	Analog system power supply	AVDD, AVDD

Note: • Do not drive external loads with the output voltage from the internal power supply circuits.

• See Chapter 7, "Electrical Characteristics", for voltage values and drive capability.

		VDD			Internal
		AVDD
				VD1	circuits
		VD1
			Oscillation system		Oscillation	OSC1~4
			voltage regulator		circuit
		VC1
External	+	VC23
power	-	VC4
supply		VC5
			LCD system
		CA	voltage circuit	VC1 ~ VC5	LCD driver	COM0~16
						SEG0~39
		CB
		CC
		AVSS
		VSS

Fig. 2.1.1 Configuration of power supply

2.1.1 Voltage <VD1> for oscillation circuit and internal circuits

VD1 is a voltage for the oscillation circuit and the internal logic circuits, and is generated by the oscillation system voltage regulator for stabilizing the oscillation. The VD1 voltage is fixed at 2.1 V, so it is not necessary to control by software.

2.1.2 Voltage <VC1–VC5> for LCD driving

VC1, VC23, VC4 and VC5 are the LCD (1/4 bias) drive voltages generated by the LCD system voltage circuit. These four output voltages can only be supplied to the externally expanded LCD driver.

The LCD system voltage circuit generates VC23 with the voltage regulator built-in, and generates three other voltages by boosting or reducing the voltage of VC23. Table 2.1.2.1 shows the VC1, VC23, VC4 and VC5 voltage values and boost/reduce status.

Table 2.1.2.1 LCD drive voltage when generated internally

LCD drive voltage	Boost/reduce status	Voltage value [V]
VC1	VC2 ⋅ 0.5	1.13
VC23	VC2 (standard)	2.25
VC4	VC2 ⋅ 1.5	3.38
VC5	VC2 ⋅ 2	4.50

Refer to Section 4.7, "LCD Driver", for control of the LCD drive voltage.

Note: The LCD drive voltage can be adjusted by the software (see Section 4.7.5). Values in the above table are typical values.

8 EPSON S1C63558 TECHNICAL MANUAL