7547 datasheet(74/91 Pages) RENESAS

74 / 91 page

7547 Group

Rev.1.21

Nov 15, 2006

page 74 of 89

REJ03B0156-0121

Power-on reset circuit characteristics

(VCC = 1.8 to 5.5 V, VSS = 0 V, Ta = –20 to 85 °C, unless otherwise noted)

Valid start voltage of power-on reset circuit (Note)

VPOR hold time

Rising time of valid power source of power-on reset circuit

Min.

Typ.

Max.

Symbol

Parameter

Limits

Unit

Test conditions

VPOR

TW(VPOR)

TW(VPOR-VDET)

Note: VPOR is the start voltage level of Vcc for the built-in power-on reset circuit to operate normally.

Keep VPOR to be lower than the Vcc voltage before rising of the Vcc power source to use the built-in power-on reset circuit.

Set the built-in low voltage detection circuit to be valid when the built-in power-on reset is used.

TW(VPOR) > 10 s

Low voltage detection circuit characteristics

(VCC = 1.8 to 5.5 V, VSS = 0 V, Ta = –20 to 85 °C, unless otherwise noted)

Valid start voltage of low voltage detection circuit (Note)

VLVD hold time

Rising time of valid power source of low voltage detection circuit

Detection voltage of low voltage detection circuit

Detection voltage Hysteresis (when hysteresis is valid)

Detection time of low 5voltage detection circuit

Min.

1.0

1.85

1.8

Typ.

1.95

0.1

Max.

Symbol

Parameter

Limits

Unit

Test conditions

µs

2.05

2.1

VLVD

TW(VLVD)

TW(VLVD-VDET)

VDET-

V(VDET+–VDET-)

TDET

Note: VLVD is the start voltage level of Vcc for the built-in low voltage detection circuit to operate normally.

If the Vcc power source becomes lower than VLVD, first set the Vcc voltage to be lower than VPOR. Next, according to the electrical characteristics of

the power-on reset circuit, perform the rising of Vcc.

TW(VLVD) > 10 s

Ta = 0 to 50 °C

Ta = –20 to 85 °C

Fig. 92 Electrical characteristics of power-on reset circuit and voltage drop detection circuit

Vcc power source

waveform

VPOR

TW(VPOR)T(VPON-VDET)

TDET

TW(VLVD)T(VLVD-VDET)

Note

VDET+

VDET-

Internal reset signal

Power-on reset circuit

characteristics

Low voltage detection circuit

characteristics

Note: If the schmitt of the voltage drop detection circuit is set to be invalid, system is released from reset at the timing of rising to

power source voltage VDET-.

VPOR

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