HA16129AFPJ

Rev.1.00 Jun 15, 2005 page 5 of 22

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.

Short Detection Block

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

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

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.