BD64550EFV データシートの表示（PDF） - ROHM Semiconductor

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BD64550EFV

System Driver for Ink Jet Printers

ROHM Semiconductor 

BD64550EFV

Technical Note

●Switching regulator operation

○Basic operation

A switching regulator circuit that repeats on/off being synchronized with internal CLK (200 KHz) is built-in.

The start up output voltage SWOUT (pin 12) becomes up and run step by step with soft start at the VM power-on

(VM≧VMPORH).The output voltage is determined by the equation below with external resistance.

VOUTDCDC=VBIAS・｛(R1+R2)/R2 ｝ [V]

The setting should be performed so that the switching regulator output voltage (VOUTDCDC) waveform is optimized within

the range of VOUTDCDC = 3V to 5V, VBIAS = 0.9V (Typ.), R1 + R2 = 1kΩ to 10kΩ, C1 = 1,000pF to 10,000pF.

DSEN

-

++

0.9V

BIAS

DAC

SWOFF

SS

COUNTER

200KHzCLK

DRIVER

CLK（=1.95kHz）

SWOUT

VOUTDCDC

R1

C1

DSEN

R2

Fig.22 Switching Regulator Block Diagram

Reference clock

（200kHz）

DUTY MAX

Output voltage

SWOUT

MAX_DUTY 92%

Fig.23 Timing Chart of Switching Regulator Operation

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© 2010 ROHM Co., Ltd. All rights reserved.

9/16

2010.06 - Rev.A

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