UPC1935 データシートの表示（PDF） - NEC => Renesas Technology

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UPC1935

DC-DC CONVERTER CONTROL IC

NEC => Renesas Technology 

µ PC1935

2.1 Reference Voltage Generator

The reference voltage generator is comprised of a band-gap reference circuit, and outputs a temperature-compensated

reference voltage (2.1 V). The reference voltage can be used as the power supply for internal circuits, or as a reference

voltage, and can also be accessed externally via the VREF pin (pin 2).

2.2 Oscillator

The oscillator self-oscillates if a timing resistor is attached to the RT pin (pin 3). This oscillator waveform is input to the

inverted input pins (channel 1 and 2) or non-inverted input pin (channel 3) of the three PWM comparators to determine the

oscillation frequency.

2.3 Under Voltage Lock-out Circuit

The under voltage lock-out circuit prevents malfunctioning of the internal circuits when the supply voltage is low, such as

when the supply voltage is first applied, or when the power supply is interrupted. When the voltage is low, the three output

transistors are cut off at the same time.

2.4 Error Amplifiers

The non-inverted input pins of the error amplifiers E/A1, E/A2, and E/A3 are connected internally to 0.3 V (the input

threshold voltages are all 0.3 V (TYP.)). The circuits of the error amplifiers E/A1, E/A2, and E/A3 are exactly the same. The

first stage of the error amplifier is a P-channel MOS transistor input.

2.5 PWM Comparators

The output ON duty is controlled according to the outputs of the error amplifiers and the voltage input to the Dead Time

Control pin (fixed internally for channel 1).

A triangular waveform is input to the inverted pin, and the error amplifier output and Dead Time Control pin voltage (fixed

internally for channel 1) are input to the non-inverted pins of the PWM comparators for channel 1 and channel 2.

Therefore, the output transistor ON period is the period when the triangular waveform is lower than the error amplifier

output and Dead Time Control pin voltage (fixed internally for channel 1).

Channel 3 is the logical inverse of channel 1 and channel 2. Consequently, the triangular waveform is input to the non-

inverted input pin, and the error amplifier output and Dead Time Control pin voltage are input to the inverted input pins of

the PWM comparator for channel 3. Therefore, the transistor ON period is the period when the triangular waveform is

higher than the error amplifier output and Dead Time Control pin voltage (refer to Timing Charts).

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Data Sheet G13418EJ3V0DS00

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