S-1721 Seiko Instruments, S-1721 Datasheet - Page 19

• Manufacturer Part Number: S-1721
• Description: SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR
• Manufacturer: Seiko Instruments

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Rev.1.1
(1) S-1721 Series A, B, C, D Types
3. ON/OFF pin 1 and 2
B (2ch), C (1ch), D types
SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR
These pins start and stop the regulator.
When the ON/OFF pin is set to the power-off level, the entire internal circuit stops operating, and the built-in P-
channel MOS FET output transistor between the VIN and VOUT pin is turned off, in order to reduce the current
consumption significantly. The VOUT pin is set to the VSS level by the internal dividing resistor of several hundred
kΩ which is placed between the VOUT and VSS pin. Note that the current consumption increases when a voltage of
0.3 V to 1.2 V (@Ta = 25°C) is applied to the ON/OFF pin.
The ON/OFF pin is configured as shown in Figures 24 and 25. In the S-1721 Series A, B C, and D types, the
ON/OFF pin is internally pulled up to VIN or pulled down to VSS when in the floating status, so the VOUT pin is set
to the VSS level.
In the S-1721 Series E, F, G and H types, do not use S-1721 Series in the floating status because the ON/OFF pin
is not internally pulled up or pulled down.
When not using the ON/OFF pin in the S-1721 Series E, F, G, and H types, connect the ON/OFF pin to the VIN pin
in the E, F (1ch only), and G (2ch only) types. In the F (2ch only), G (1ch only) and H types, connect the ON/OFF pin
to the VSS pin.
A, B (1ch), C (2ch) type
_00
Logic Type
C
D
G
H
A
B
E
F
ON/OFF
1ch “H”: Power on
2ch “H”: Power on
1ch “H”: Power on
2ch “L”: Power on
1ch “L”: Power on
2ch “H”: Power on
1ch “L”: Power on
2ch “L”: Power on
1ch “L”: Power off
2ch “L”: Power off
1ch “L”: Power off
2ch “H”: Power off
1ch “H”: Power off
2ch “L”: Power off
1ch “H”: Power off
2ch “H”: Power off
Figure 24
ON/OFF Pin
Seiko Instruments Inc.
VSS
VIN
Operate
Operate
Operate
Operate
Operate
Operate
Operate
Operate
Internal
Circuits
Stop
Stop
Stop
Stop
Stop
Stop
Stop
Stop
Table 8
(2) S-1721 Series E, F, G, H Types
VOUT Pin Voltage
Set value
Set value
Set value
Set value
Set value
Set value
Set value
Set value
V
V
V
V
V
V
V
V
SS
SS
SS
SS
SS
SS
SS
SS
ON/OFF
level
level
level
level
level
level
level
level
Figure 25
VSS
S-1721 Series
VIN
Consumption
Current
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
SS1
SS1
SS1
SS1
SS1
SS1
SS1
SS1
SS2
SS2
SS2
SS2
SS2
SS2
SS2
SS2
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