AN8032 データシートの表示（PDF） - Panasonic Corporation

部品番号

コンポーネント説明

メーカー

AN8032

Active filter control IC

Panasonic Corporation 

AN8032

s Application Notes (continued)

[2] Operation descriptions (continued)

1. Normal control (continued)

3) Description of each function (continued)

(1) VB (continued)

ID

SDB

VB lower limit

voltage clamp

current

VB upper limit

voltage clamp

current

VCC

VB

AN8032

VB

Lower limit

voltage clamp

IDS

Voltage Regulators

IDS

ID

Time

Clamp upper

limit voltage

VB

VB

threshold value

Upper limit

voltage clamp

GND

Clamp upper

limit voltage

Reset operation

of inductor

Time

Figure 5. Explanation of VB operation

<Setting the VB terminal constant>

• Regulation by clamper in/out-current value

The allowable output current of the upper

limit voltage clamper is −5 mA and the allow-

able input current of the lower limit voltage

clamper is +5 mA. Either one of these allow-

able values is exceeded, the voltage clamp op-

eration of the VB terminal is not guaranteed.

Therefore, RB should be set so that these values

are not exceeded.

• Consumption current and delay

When the RB value is too large, the VB

threshold could be exceeded. When the RB value

is too small, the consumption current becomes

too large.

In order to determine the RB value prop-

erly, the input voltage range and the dispersion

of components should be taken into consider-

ation and it should be confirmed that a stable

operation can be ensured under start/overload

conditions or under a small load condition.

AN8032

VB

±5 mA or less

RB

RB too large: Consumption current becomes small, however,

TOFF is extended by the delay amount because of low speed.

RB too small: Speed is high, however, consumption current

is small and undershoot tends to be generated easily.

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