S-1721 Datasheet, PDF (19/38 Pages) Seiko Instruments Inc – SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR

SUPER-SMALL PACKAGE 2-CIRCUIT HIGH RIPPLE-REJECTION LOW CURRENT CONSUMPTION LOW DROPOUT CMOS VOLTAGE REGULATOR
Rev.1.1_00
S-1721 Series
3. ON/OFF pin 1 and 2
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.
Logic Type
ON/OFF Pin
1ch “H”: Power on
A
2ch “H”: Power on
B
1ch “H”: Power on
2ch “L”: Power on
C
1ch “L”: Power on
2ch “H”: Power on
D
1ch “L”: Power on
2ch “L”: Power on
E
1ch “L”: Power off
2ch “L”: Power off
F
1ch “L”: Power off
2ch “H”: Power off
G
1ch “H”: Power off
2ch “L”: Power off
H
1ch “H”: Power off
2ch “H”: Power off
Table
Internal
Circuits
Operate
Operate
Operate
Operate
Operate
Operate
Operate
Operate
Stop
Stop
Stop
Stop
Stop
Stop
Stop
Stop
8
VOUT Pin Voltage
Set value
Set value
Set value
Set value
Set value
Set value
Set value
Set value
V_SS level
V_SS level
V_SS level
V_SS level
V_SS level
V_SS level
V_SS level
V_SS level
Current
Consumption
I_SS1
I_SS1
I_SS1
I_SS1
I_SS1
I_SS1
I_SS1
I_SS1
I_SS2
I_SS2
I_SS2
I_SS2
I_SS2
I_SS2
I_SS2
I_SS2
(1) S-1721 Series A, B, C, D Types
VIN
(2) S-1721 Series E, F, G, H Types
VIN
B (2ch), C (1ch), D types
ON/OFF
A, B (1ch), C (2ch) type
Figure 24
VSS
ON/OFF
VSS
Figure 25
Seiko Instruments Inc.
19