HA16129FPJ Datasheet, PDF (5/23 Pages) Hitachi Semiconductor – Single Watchdog Timer

HA16129FPJ
Functional Description
This section describes the functions provided by the HA16129FPJ. See the section on formulas for details on
adjustment methods.
Regulator Block
• Vout Voltage
This IC provides a stabilized 5 V power supply by controlling the base current of an external transistor. The largest
current (the maximum CONT pin current) that can be drawn by the base of this external transistor is 20 mA. Also
note that the Vout output is also used for the power supply for this IC’s internal circuits.
Current Limiter Block
When a current detection resistor (R_CS) is connected between the V_CC pin and the CS pin, and the voltage between these
pins exceeds the V_CS voltage (150 mV Typ), the CONT pin function turns off and the output voltage supply is stopped.
This function can not work when V_OUT < 2 V.
Note: This function is not short detection.
Output Voltage (Vout) Adjustment
The output voltage can be adjusted by connecting an external resistor at the output voltage adjustment pin (Voadj).
However, if for some reason the voltage on this Vout line increases and exceeds the voltage adjustment range (7 V
Max), the CONT pin function turns off and the output voltage supply is stopped.
Refer to the timing charts in conjunction with the following items.
LVI (Low Voltage Inhibit)
• NMI Detection Voltage
This function monitors for drops in the power-supply voltage. This function can be set up to monitor either V_CC or
Vout. When Vout is monitored, a low level is output from the NMI pin if that voltage falls under the detection
voltage (4.63 V Typ). Then, when the power-supply voltage that fell rises again, the NMI pin will output a high
level. Note that this function has a fixed hysteresis of 50 mV (Typ). The monitored power supply is selected by
connecting the NMIsns pin either to the V_CC pin or to the V_OUT pin. When detecting V_CC, an external adjustment
resistor is required.)
The detection voltage can also be adjusted with the NMIadj pin.
• STBY Detection Voltage
This function monitors for drops in the Vout voltage. It monitors the Vout voltage, and outputs a low level from the
STBY pin if that voltage drops below the detection voltage (3.0 V Typ). Then, when the power-supply voltage that
fell rises again, the STBY pin will output a high level. Note that this function has a fixed hysteresis of 1.35 V (Typ).
The detection voltage can also be adjusted with the STBYadj pin.
Function Start Voltage
This is the minimum required Vout voltage for the RES, NMI, STBY, and OUTE output pin functions to start operating.
It is stipulated as the voltage that Vout must reach after power is first applied for these pins to output a low level.
Hysteresis
This is the difference between the LVI function detection voltage when the power-supply voltage drops, and the clear
(reset) voltage when the power-supply voltage rises.
(V_HYSN = V_NMI' – V_NMI; V_HYSS = V_STBY' – V_STBY)
Rev.3.00 Jun 15, 2005 page 5 of 22