UCC24636DBVT datasheet(19/35 Pages) TI1

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UCC24636

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SLUSCG2A – MARCH 2016 – REVISED MARCH 2016

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8.4 Device Functional Modes

According to VDD voltage, VSC voltage, and VPC voltage and frequency, the device can operate in different

modes.

8.4.1 Start-Up

During start-up when VDD is less than VVDD(on) the device is disabled. When VDD exceeds the VVDD(on) UVLO

threshold the IDD goes to IRUN and the device begins the start sequence detailed in Start Up and UVLO.

8.4.2 Normal Operation

When VDD exceeds VVDD(on), the VPC voltage exceeds VVPC-EN and VVPC-TH, and the VSC voltage exceeds

VVSCEN the DRV output is active. If the switching frequency is above the standby criteria of > 5 kHz the device is

in normal operation determining the DRV time based on volt-sec control. IDD will be IRUN.

1. The device operates in volt-sec control based on the VPC and VSC volt-sec control ramps.

8.4.3 Standby Operation

If the number of VPC pulses is less than nENTO, 64, during tENTO the device enters standby mode. DRV operation

stops and most device functions are shut down. IDD is ISTBY during standby operation. To exit standby mode the

number of VPC pulses must exceed nEN, 32, during tEN. IDD returns to IRUN and the DRV output starts after the

initialization time as outlined in Figure 12.

8.4.4 Conditions to Stop Operation

The following conditions can disable DRV operation; IDD is IRUN during these conditions.

1. VPC overvoltage: When VVPC > VVPCDIS for >500 ns the DRV output is disabled for the cycle.

2. VSC undervoltage: When VVSC < VVSCEN, the DRV output is disabled.

3. VPC undervoltage: When VVPC< VVPCEN, the DRV output is disabled.

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