S-1702 Datasheet, PDF (25/45 Pages) Seiko Instruments Inc – Built-in overcurrent protection circuit

SUPER-LOW CURRENT CONSUMPTION 150 mA VOLTAGE REGULATOR WITH BUILT-IN HIGH-ACCURACY VOLTAGE DETECTOR AND RESET INPUT FUNCTION
Rev.2.2_01
S-1702 Series
2. 2. 1 Output transistor
The S-1702 Series regulator block uses a low on-resistance Pch MOS FET transistor as the output transistor.
Caution Be sure that VOUT does not exceed VIN + 0.3 V to prevent the voltage regulator from being
damaged due to inverse current flowing from the VOUT pin through a parasitic diode to the
VIN pin, when the potential of VOUT became higher than VIN.
2. 2. 2 Discharge shunt function
The discharge shunt function is enabled in the S-1702Axx, Bxx, Cxx, Exx, Fxx, Gxx, Jxx, Lxx, and Nxx.
When the regulator block is stopped, the output transistor is turned off and the discharge shunt circuit is
turned on according to the combination of the ON / OFF and the RESX pins.
This operation causes the charge in the output capacitor (CL) to be discharged, and forcibly sets the VOUT
pin the VSS level.
The VOUT pin is set at the VSS level in a shorter time than the S-1702Dxx, Hxx, Kxx, Mxx, and Pxx, because
they disable the discharge shunt function.
VIN
ON / OFF
RESX
Output transistor: OFF
*1
V_IN
Reference
voltage
circuit
V_ref
−
+
ON / OFF
circuit
Reset circuit
R_f
V_fb
R_s
Logic
circuit
S-1702 Series
V_OUT
Discharge
shunt circuit :
ON
*1
VOUT
Current flow
C_L
Output capacitor
VSS
*1. Parasitic diode
Figure 27 Discharge Shunt Function
GND
25