NJM2352D Просмотр технического описания (PDF) - Japan Radio Corporation

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NJM2352D

LOW POWER SWITCHING REGULATOR

Japan Radio Corporation  

NJM2352

■ MINIMUM OPERATING VOLTAGE

Minimum operating voltage is V+ ≥ 2.6V at 25°C and its temperature coefficient is negative. Be careful when you

design. Less than this minimum operating voltage, internal switching transistor becomes on, and the surge-like high

current flows into it especially in Step-Up or Inverting application.

■ OSCILLATOR

Oscillator frequency is decided by putting a capacitor into PIN 2. The amplitude of both square wave A and triangular

wave B is between 1 VBE and 3VBE.

■ AMPLIFIER

AMP source current it 20 µA max. and so the feedback resistor R1 to be connected to PIN 6 and PIN 7 are

recommended more than 100kΩ.

■ SWITCHING TRANSISTOR

When the negative voltage more than 0.5V absolute value based on ground level is applied, the NJM2352 may

operate unordinary by reason of parasitic effect in it. And so put SBD in between PIN 3 and ground when you drive

directory coil with internal switching transistor.

NJM2352

■ DETECTION CIRCUIT OF INPUT VOLTAGE DROP

When input voltage becomes lower than specified voltage, transistor Q56 switches on and indicative device like LED

turns on. The specified voltage is decided by internal reference voltage and outer resistors ratio.

VTH = VREF (1+R2/R5) + R2 x 0.5µA

When - input voltage becomes lower than + input voltage, PIN 1 of COMP-3 sinks about 1µA and thus prevents

chattering. Transistor Q56 becomes off condition when PIN 1 voltage is lower than about 0.2V. It is recommendable to

put about 1µF to PIN 1 in actual application to avoid switching noise.

- 10 -

Ver.2003-07-18

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