Ns

GND

UCC24636

VPC

DRV

GND

TBLK

VSC

VDD

3.0

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

4.1

4.2

4.3

4.4

4.5

0.5

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

VPC V-us (uWb)

C008

13

UCC24636

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SLUSCG2A – MARCH 2016 – REVISED MARCH 2016

Product Folder Links: UCC24636

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Copyright © 2016, Texas Instruments Incorporated

Feature Description (continued)

The UCC24636 is designed to operate in a variety of flyback converter applications over a wide operating range.

The internal volt-sec control ramps do have a dynamic range limit based on volt-sec on the VPC pin. As shown

in Figure 14, a Volt-sec product exceeding 7 V-µs on the VPC pin will result in saturation of the VPC volt-sec

the device. Assuming a converter operating in transition mode at low line and full load with a 50% duty cycle, the

operating period is 28 µs which results in a frequency that is under 40 kHz. The UCC24636 low-frequency

should be less than 7 V-µs.

The device can support switching frequencies exceeding 130 kHz but the following timing limits need to be

confirmed to be compatible with the power train. The minimum primary on time when the device is expected to

Figure 15. SR Controller Components