UPC1934 Просмотр технического описания (PDF) - NEC => Renesas Technology

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UPC1934

DC-DC CONVERTER CONTROL IC

NEC => Renesas Technology 

µ PC1934

3.2 Setting the Oscillation Frequency

Choose RT according to the oscillation frequency (fOSC) vs timing resistor (CT, RT) characteristics (refer To Typical

Characteristics Curves fOSC vs CT, RT). The formula below (3-1) gives an approximation of fOSC. However, the result of

formula 3-1 is only an approximation, and the value must be confirmed in actual operation, especially for high-frequency

operation.

fOSC [Hz] ≅ 0.375/(CT [F] x RT [Ω]) (3-1)

3.3 Preventing Malfunction of the Timer Latch-Method Short Circuit Protection Circuit

The timer latch short-circuit protection circuit operates when the error amplifier outputs (pin 5 and 12) goes below

approximately 0.63 V, and cuts off the output. However, if the rise of the power supply voltage is fast, or if there is noise on

the DLY pin (pin 15), the latch circuit may malfunction and cut the output off.

To prevent this, lower the wiring impedance between the DLY pin and the GND pin (pin 8), and avoid applying noise to

the DLY pin.

3.4 Connecting Unused Error Amplifiers

When one of the two control circuits is used, connect the circuit so that the output of the error amplifier of unused circuit

is high. Figure 3-2 shows examples of how to connect unused error amplifiers.

Figure 3-2 Examples of Connecting Unused Error Amplifiers

(1) Error amplifier E/A1

16 VREF

3

E/A1

4

5

6 DTC1

(2) Error amplifier E/A2

16 VREF

14

E/A2

13

12

11 DTC2

Data Sheet G13567EJ3V0DS00

13

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