HA16129FPJ Datasheet, PDF (7/23 Pages) Hitachi Semiconductor – Single Watchdog Timer

HA16129FPJ
Calculation Formulas
Item
Reference
voltage
Formula
( Vout = 1.225 1 + 37 // R1
12 // R2
R1, R2; kΩ
Notes
While the Vout voltage will be 5 V ±1.5% when the Voadj
pin is open, the circuit shown here should be used to change
the Vout voltage externally.
Current
limiter
voltage
V_CS (150 mV Typ) < I_L ⋅ R_CS
V_CC CS
Vout
R1
Voadj
R2
When this function operates, the base current to the external
transistor connected to the CS pin stops and the Vout output
is lowered.
R_CS
I_L
V_CC CS
Vout
OVP
t_RH, t_RL
t_ON
t_OFF
—
t_RH = 3.3 × C_R ⋅ R_R
t_RL = 1.1 × C_R ⋅ R_R
t_ON = 1.1 × C_R ⋅ R_T
t_OFF = 6.5 × C_R ⋅ R_R
This function prevents the microprocessor from being
damaged if the Vout voltage is inadvertently increased to too
high a level. The OVP detection voltage is fixed.
These determine the reset pulse frequency and duty.
RES
t_RL
t_RH
Sets the time from the rise of the NMI signal to the point the
RES output is cleared.
NMI
RES
t_ON
Sets the time from the point the P-RUN pulse stops to the
point a reset pulse is output.
P-RUN
RES
toff
Rev.3.00 Jun 15, 2005 page 7 of 22