SCI7638 データシートの表示（PDF） - Seiko Epson Corp

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SCI7638

POWER SUPPLY IC - DC/DC Switching Regulators

Seiko Epson Corp 

SCI7630 Series

PWCR

VO circuit

RST

VI1 circuit

VI1

Output voltage response compensation

The SCI7638 series are provided with a response com-

pensation input. A response compensation capacitor is

connected between VCONT and VO, allowing the ripple

voltage generated by the boosted output voltage to be

suppressed to a minimum.

Standby mode and battery backup

The SCI7631 series are equipped with a standby mode,

initiated by connecting PS to GND.

In standby mode, the booster, including the crystal os-

cillator, is disabled (the switching transistor used to

drive the inductor is turned OFF) and the built-in

backup switch is turned ON, so that the input voltage at

VI2 is output at VO. This enables the battery backup

function. PS is pulled-up internally, so when standby

mode is not required, the pin should be left open.

Powering up

Ensure that V0 is at least the minimum operating volt-

age (0.9V) before switching on the booster circuit.

One way to do this is to attach a battery so that V0 never

drops below the minimum required for backup mode. If

no such external power supply is available, connect VI2

to VI1 and hold PS LOW when applying power for the

first time.

Battery

VI2

PS

C SCI7631M

TYPICAL APPLICATIONS

Example Circuits

The output current, IO, and power conversion effi-

ciency, Peff of a particular device in a series depends on

SCI7631 series

L

D

factors such as the switching frequency, type of coil,

and the size and type of other external components.

SCI7638 series

L

D

VSW

VI1

VO

VI2 SCI7631M/C

GND

PWCR

R1

C1

VSW

VI1

VO

SCI7638M/C

GND

VCONT

C1

PS RST

PWCR PS RST

SCI7000 Series

Technical Manual

EPSON

4–15

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