HA16114PJ View Datasheet(PDF) - Renesas Electronics

Part Name

Description

Manufacturer

HA16114PJ

Switching Regulator for Chopper Type DC/DC Converter

Renesas Electronics 

HA16114P/PJ/FP/FPJ, HA16120FP/FPJ

5. Voltage Reference (Vref = 2.5 V)

5.1 Voltage Reference

A bandgap reference built into the IC (see figure 5.1) outputs 2.5 V ± 50 mV. The sawtooth oscillator,

PWM comparator, latch, and other internal circuits are powered by this 2.5 V and an internally-generated

voltage of approximately 3.2 V.

The voltage reference section shut downs when the IC is turned off at the ON/OFF pin as described later,

saving current when the IC is not used and when it operates in intermittent mode during overcurrent.

ON/OFF

−

+

1.25 V

Sub bandgap circuit

Main bandgap circuit

VIN

1.25 V

25 kΩ

25 kΩ

3.2 V

Vref

2.5 V

ADJ

Figure 5.1 Vref Reference Circuit

5.2 Trimming the Reference Voltage (Vref and ADJ pins)

Figure 5.2 shows a simplified circuit equivalent to figure 5.1. The ADJ pin in this circuit is provided for

trimming the reference voltage (Vref). The output at the ADJ pin is a voltage VADJ of 1.25 V (Typ)

generated by the bandgap circuit. Vref is determined by VADJ and the ratio of internal resistors R1 and R2 as

follows:

Vref = VADJ ×

R1 + R2

R2

The design values of R1 and R2 are 25 kΩ with a tolerance of ±25%.

If trimming is not performed, the ADJ pin open can be left open.

VIN

Vref

R1

25 kΩ

(typ)

ADJ

R2

25 kΩ

(typ)

VBG (bandgap voltage)

1.25 V (typ)

Figure 5.2 Simplified Diagram of Voltage Reference Circuit

Rev.2.0, Sep.18.2003, page 13 of 37

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