S1F76540 Series

 

 

 

 

 

 

 

Reference Voltage Circuit

 

 

 

 

 

 

The S1F76540 has a built-in reference voltage circuit

ence voltage and the external resistance. The reference

for voltage regulation.

The regulated voltage (ex-

voltage can be used to change the temperature coeffi-

plained in the next “voltage regulator circuit” section) is

cient at pins TC1 and TC2. One of four states can be

set depending on the division ratio between this refer-

selected as listed on Table 2.6.

 

 

Table 2.6 Setup of reference voltage and temperature coefficient

 

 

 

 

 

 

 

 

 

TC1

TC2

Reference voltage,

Temperature coefficient,

 

(High = VDD) (High = VDD)

 

VREF (V)

 

 

CT (%/°C)

 

 

 

 

 

 

 

 

 

 

Mode

(Low = VI)

(Low = VI)

Min.

Typ.

Max.

Min.

Typ.

Max.

 

 

 

 

 

 

 

 

 

CT0

High

High

–1.55

–1.5

–1.45

–0.07

–0.04

0

 

 

 

 

 

 

 

 

 

CT1

High

Low

–1.70

–1.5

–1.30

–0.25

–0.15

–0.07

 

 

 

 

 

 

 

 

 

CT2

Low

High

–1.90

–1.5

–1.10

–0.45

–0.35

–0.20

 

 

 

 

 

 

 

 

 

CT3

Low

Low

–2.15

–1.5

–0.85

–0.75

–0.55

–0.30

 

 

 

 

 

 

 

 

 

Notes: 1. The reference voltage is given at Ta = 25°C.

2.The reference voltage and temperature coefficient of the chip products may vary depending on the moldings used on each chip. Use these chips only after the temperature test.

The temperature coefficient (CT) is defined by the following equation. The negative sign of the temperature coefficient (CT) means that the VREF value decreases when the temperature rises.

CT =

VREF (50°C) – VREF (0°C)

×

100

 

 

50°C – 0°C

VREF (25°C)

Notes on TC1 and TC2 pin replacement:

•When replacing the TC1 and TC2 pins after power-on, always select the power-off mode (POFF1 = POFF2 = VI) and replace them by each other.

S1F76540

Series

 

 

Voltage Regulator Circuit

The voltage regulator circuit regulates a voltage entered in the VRI pin and can output any voltage. It uses the series voltage regulation. As shown in Figure 2.5, the VRI and VO pins must be short-circuited by a jumper as short as possible except for larger time boosting by using external diodes.

As shown by equation (1), any output voltage can be set by the ratio of external division resistors R1 and R2. The sum of division resistance is recommended to be

small as possible to avoid an external noise interfer- ence. As the current consumed by division resistors (equation (2)) flows, the 100Ω to 1MΩ are recommended to use.

The temperature coefficient of the regulated voltage is equal to the temperature coefficient of the reference voltage that is explained in the “reference voltage cir- cuit” section.

S1F70000 Series Technical Manual

EPSON

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