4 POWeR SuPPlY
S1C17624/604/622/602/621 TeChniCal Manual
Seiko epson Corporation
4-1
Power Supply
4
Power Supply Voltage (V
4.1
DD
)
The operating voltage range of the S1C17624/604/622/602/621 is as follows:
For normal operation:
V
DD
= 1.8 V to 3.6 V
For Flash programming: V
DD
= 2.7 V to 3.6 V
S u p p l y a vo l t a g e w i t h i n t h e r a n g e t o t h e V
D D
p i n s w i t h t h e V
S S
p i n s a s t h e G N D l eve l . T h e
S1C17624/604/622/602/621 provides two or more V
DD
and V
SS
pins. Do not leave any power supply pins open and
be sure to connect them to + power source and GND.
analog Power Supply Voltage (aV
4.2
DD
)
The analog power supply pin (AV
DD
) is provided separately from the V
DD
pin in order that the digital circuits do
not affect the analog circuits (A/D converter). The AV
DD
pin is used to supply an analog power voltage and the V
SS
pin is used as the analog ground. The following voltage is enabled for AV
DD
:
AV
DD
= V
DD
= 1.8 V to 3.6 V (V
SS
= GND)
note: Be sure to supply the same voltage as V
DD
to the AV
DD
pin even if the analog circuit is not used.
Noise on the analog power lines decrease the A/D converting precision, so use a stabilized power supply and make
the board pattern with consideration given to that.
internal Power Supply Circuit
4.3
The S1C17624/604/622/602/621 has a built-in power supply circuit shown in Figure 4.3.1 to generate all the power
voltages required for the internal circuits. The power supply module consists of two circuits.
3.1 Power Supply Circuit
Table 4.
Circuit
Power supply circuit
Output voltage
Oscillator and internal logic circuits Internal logic voltage regulator
V
D1
LCD driver
LCD system voltage regulator
V
C1
to V
C3
V
D1
External
power
supply
Oscillator
Internal logic
voltage regulator
Internal circuit
OSC1, OSC2
OSC3, OSC4
V
D1
V
C1
V
C2
V
C3
CA
CB
V
SS
AV
DD
V
DD
A/D converter
AIN
x
LCD driver
COM
x
SEG
x
LCD system
voltage regulator
V
C1
–V
C3
VCSEL
LHVLD
VD1MD
HVLD
3.1 Configuration of Power Supply Circuit
Figure 4.
note: Be sure to avoid using the V
D1
and V
C1
–V
C3
pin outputs to drive external circuits.