S-8540A15FN-IAAT2Z Datasheet, PDF (12/36 Pages) Seiko Instruments Inc – SWITCHABLE SWITCHING REGULATOR CONTROLLER

STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
S-8540/8541 Series
Rev.4.0_01
3. ON/ OFF pin (shutdown pin)
This pin deactivates or activates the step-down operation.
When the ON / OFF pin is set to "L", the VIN voltage appears through the EXT pin, prodding the
switching transistor to go off. All the internal circuits stop working, and substantial savings in current
consumption are thus achieved.
The ON / OFF pin is configured as shown in Figure 10. Since pull-up or pull-down is not performed
internally, please avoid operating the pin in a floating state. Also, try to refrain from applying a voltage of
0.3 to 1.8 V to the pin, lest the current consumption increase. When this ON / OFF pin is not used,
leave it coupled to the VIN pin.
ON / OFF Pin
“H”
“L”
Table 7
CR Oscillation Circuit
Activated
Deactivated
Output Voltage
Set value
OPEN
VIN
ON/OFF
VSS
Figure 10
12