AN8049 データシートの表示（PDF） - Panasonic Corporation

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AN8049

1.8-volt 3-channel step-up, step-down, and polarity inverting DC-DC converter control IC

Panasonic Corporation 

Voltage Regulators

AN8049SH

I Usage Notes

[1] Allowable power dissipation

1. Since the power dissipation (P) in this IC increases proportionally with the supply voltage, applications must be careful

to operate so that the loss does not exceed the allowable power dissipation, PD, for the package. See the PD  Ta curve.

Reference formula:

P = (VCC −VBEQ1) × ISO(OUT)1 × Du1 + (VCC − VBEQ2) × ISO(OUT)2 × Du2 + VO(SAT)3 × IOUT3 × Du3 + VCC × ICC

< PD

VBEQ1 : The voltage between the base and emitter of the channel 1 npn transistor

ISO(OUT)1 : The OUT1 pin output source current

(This is set by the resistor connected to the RB1 pin. When RB is 1 kΩ, ISO(OUT)1 will be 34 mA,

maximum.)

Du1 : The output 1 on-duty

VBEQ2 : The voltage between the base and emitter of the channel 2 npn transistor

ISO(OUT)2 : The OUT2 pin output source current

(This is set by the resistor connected to the RB2 pin. When RB is 1 kΩ, ISO(OUT)2 will be 34 mA,

maximum.)

Du2 : The output 2 on-duty

VO(SAT)3 : The OUT3 pin saturation voltage (0.5 V maximum when IOUT3 is 40 mA.)

IOUT3 : The OUT3 pin current (This will be {VCC − VBEQ3 − VO(SAT)3}/RO3 .)

Du3 : The output 3 on-duty

ICC

: The VCC pin current

2. If the IC is shorted to ground, shorted to VCC, or inserted incorrectly, either the device itself or peripheral

components will be destroyed.

[2] Allowable VCC ripple

VCC ripple due to the switching transistor being turned on and off can cause this IC's U.V.L.O. circuit, which is

biased by VCC, to operate incorrectly, and can cause the S.C.P. capacitor charging operation to fail to start when the

output is shorted.

The figure shows the allowable range for VCC ripple. Applications should reduce VCC ripple either by inserting a

ripple filter in the VCC line or by inserting a capacitor between the IC GND and VCC pins and locating that capacitor

as close to the IC as possible.

Note that the allowable range shown here is the result of testing the IC independently, and that the allowable range

may differ depending on the actual system of the power supply circuit. Also note that this allowable range is a design

target, and is not guaranteed by testing of all samples.

Allowable VCC ripple

10M

Allowable range

when VCC is 3 V.

1M

100k

Allowable range

when VCC is 10 V.

10k

0

1

2

3

4

5

6

7

8

VCC ripple voltage VCC(AC) (V[p-p])

11

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