Preliminary

<Setting of Output Voltage>

VOUT = RFB1 / RFB2 + 1

[ Example of Equation ]

VOUT = 3.0V

RFB1 = 200k

Ω, RFB2 = 110kΩ, CFB = 68pF

VOUT = 220k / 110k + 1 =3.0V

fzfb = 1 / (2 x

π x 68p x 220k ) = 10.64kHz

<External Components>

Tr 1, Tr 2

$ IOUT

= 2 ~ 3A

IRF7313 (Nch x 2) (IR, SO-8)

$ IOUT

= ~10A

SUP70N03-09

(Vishay, TO-220AB)

SUB70N03-09

(Vishay, TO-263)

L:

6.8

µF

(CDH127-6H1, SUMIDA)

SD 1 :

CMS02

(Schottky barrier diode, TOSHIBA)

SD 2 :

CRS02

(Schottky barrier diode, TOSHIBA)

* Please select SD2 with low reverse current.

RSENSE : Current Limit Value = 150mV / RSENSE

ex.) When RSENSE = 30m

Ω,

Current Limit = 150mV / 30m

Ω = about 5A

CPRO :

TPRO = CPRO x 1e6

ex.) When CPRO = 100pF

TPRO = 100e -12 x 1e6 =100

µS

CSS=

TSS = CSS x 3e6

ex.) When CSS = 3300pF,

TPRO = 3300e - 12 x 3e6 = 9.9mS

CBST :

0.1

µF ~ 1µF

* Please adjust according to

reverse current characteristics of SD2.

CVL :

1

µF

CIN :

22

µF

(OS-CON, SANYO)

CL :

150

µF

(OS-CON, SANYO)

Output voltage can be set by adding external split resistors. Output voltage is determined by the following equation, based on the

values of RFB1 and RFB2. The sum of RFB1 and RFB2 should normally be 2 M

Ω or less.

The value of CFB1, speed-up capacitor for phase compensation, should be fzfb= 1 / (2

× π × CFB × RFB1) which is equal to 10kHz.

Adjustments are required from 1kHz to 50kHz depending on the application, value of inductance (L), and value of load capacity

(CL).

XC9213 Series

Driver Transistor Built-In

Synchronous Step-Down DC/DC Controller Ics

Input Voltage : 25V

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