Features

User programmable maximum pulse width adjustment

DDM ratio

100 a start current

Run to 1MHz

] Internal full -cycle soft start

Inner front edge tailor

current influenza response signal

ucc3807 series of high -speed low work The consumption circuit includes all the control and driving circuit minimum external connection frequency current mode switching power part counts required for offline and DC-DC fixed.

These devices are similar to the UCC3800 series, but increase the characteristics of the user's maximum duty cycle. The frequency and maximum occupy ratio of the oscillator are programmed by two resistors and a capacitor.

The UCC3807 series also has the front edge of the internal full -cycle soft start and the internal current sensing input.

The UCC3807 series provides a variety of packaging options, temperature volume options and critical voltage levels. There are thresholds and lag of ultraviolet lines and battery power supply systems at home.

The threshold is shown in the table below.

Absolutely maximum rated value

Power voltage (IDD 10mA). Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence 13.5 il

Power supply current. Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence 30 mia

output current. 1 An

Analog input (FB, CS). Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence - 0.3v to (VDD+0.3V)

TA+25 ° C power consumption (n or J packaging). 1 tile

Power consumption (D package) at TA+25 ° C. Essence Essence Essence Essence Essence Essence Essence Essence Essence 0.65 watt

Storage temperature. Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence –65 ° C to+150 ° C

Conclusion temperature. Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence –65 ° C to+150 ° C

Lead temperature (welding, 10 seconds). Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence Essence +300 degrees Celsius

All currents are positive input and negative output. For the heat limit and packaging precautions, see the packaging part of the data manual.

The pipeline description

COMP: COMP is the input of an error amplifier and a PWM comparator. The error amplifier UCC3807 is a low output impedance with a operating frequency of 2 MMH. Comp can be both source current or exchange current. The internal current of this error amplifier is limited, allowing zero -occupying ratio through the ground forced compressor ground.

The UCC3807 series has a built -in full -cycle soft startup function.

Soft start is the maximum compensation voltage.

CS: current influenza input. There are now two comparators, PWM comparators and over -current comparators on the chip.

UCC3807 also contains a front edge consolidated circuit, which is used to disconnect the external CS signal and current influenza response comparator in a 100ns time interval. In most applications, CS does not need to simulate filtering. Compared with the external RC filtering technology, the front edge has smaller validity CS output transmission delay. However, please note that the minimum non-zero opening time of the output signal is delayed by the output transmission of the front edge and the influence of the CS-TO.

Over -current comparators are only used for fault sensors. More than the over -current threshold will cause a soft startup cycle.

FB: The reverse input of the error placing the large device. The best stability is to keep the connection with the FB as short as possible.

GND: Reference grounding and power grounding for all functions of components.

Output: The output drive peak current of the large current power drive is a grid with a power MOSFET with a power of more than 1A. When VDD is lower than the UVLO threshold.

The large current power drive consists of a Totitan MOSFET output device. This allows the output from VDD to GND. The output level provides extremely low impedance at the same time to make over and overwhelm. In most cases, the outside does not need to be clamping the diode

pins instructions (continued)

trigger/release: oscillator control tube foot. TRIG is a regular input of an oscillator and has an RC -type charging power signal control chip internal oscillator. Disk is an external RC network that provides a low -impedance loop loop pins during normal operation. Calculating oscillating frequency and maximum duty cycle are as follows:

In order to obtain the best performance, please keep the lead from CT to GND as short as possible. CT's separate ground connection is intentional. The minimum value of RA is 10k, the minimum value of RB is 2.2K, and the minimum value of CT is 47 pounds.

VDD: The power input connection of this device. The total VDD current is the sum of static current and average output current. The calculation formula of the working frequency MOSFET grid charge (QG) and the average output current is as follows. The frequency is as follows, where F is the frequency.

In order to prevent noise, use ceramic capacitors and electrolytic capacitors as close to the chip as much as possible.

oscillator box diagram

Application information

UCC3807 in typical offline applications. 100 watts, 200kHz, the general input positive input switch is generated to adjust the 12 -volts of DC power when 8 amp.The programmable maximum occupation ratio of UCC3807 allows the operation to turn off the simple RCD, which can reach 80VRMS and 265VRMS to restrict the MOSFET voltage and provide core reset.In this application, the maximum duty ratio is set to about 65%.Another feature of the design is the anti -gratitude winding on the output filter to guide binding and voltage adjustment.This loop closure method eliminates optocoupler and secondary regulators. It is usually used for most offline designs, while providing good lines and load adjustments.

Application information (continued)

Use the typical offline application of UCC3807-2