Author: SananyaM_56 Version: **
The faults in PAG1 are divided into source-side faults, load-side faults, and internal faults.
Source-Side faults | Load-Side faults | Internal faults |
Overcurrent | Overcurrent | Over temperature |
Undervoltage | Short circuit | |
Overvoltage | Undervoltage | |
Overvoltage |
For more details about the test cases and relevant procedures for these protection schemes, see the 18W PAG1S+PAG1P Design files. Also see the PAG1P Primary Side Start up Controller datasheet and PAG1S - CYPAS111 USB-PD Power Adapter Secondary Side Controller datasheet.
For all protection schemes, the following general flow of protection applies:
Fault event > Immediate protective action > Post-fault behaviour
The following changes must be made in the EZ-PD Configuration Utility tool. See the test report of the 18W PAG1P+PAG1S design file for relevant waveforms.
Figure 1. OCP feature in EZ-PD Configuration utility
See the following for PAG1 load-side protection of events. See the PAG1S - CYPAS111 USB-PD Power Adapter Secondary Side Controller datasheet for details.
Protection Feature | Fault Event | Immediate Protective Action | Post-Fault Behavior |
Overcurrent Protection | Current increases beyond the set OCP threshold. For example, 3x1.2 = 3.6 A | NGDO turns off in approximately 10 µs | Retry the set “Retry Count” times. Turn off NGDO if fault persists. For example, Retry Count = 2 |
Overvoltage Protection | Voltage exceeds the set OVP threshold. For example, 5x1.2 = 6 V | NGDO turns off in approximately 10 µs | Retry the set “Retry Count” times. Turn off NGDO if fault persists. For example, Retry Count = 2 |
Undervoltage Protection | Output voltage falls below the set UVP threshold. For example: 5x 0.7 = 3.5 V | NGDO turns off in approximately 10 µs | Retry the set “Retry Count” times. Turn off NGDO if fault persists. For example, Retry Count = 2 |
Short-Circuit Protection | Output current exceeds the threshold value of 6 A. | NGDO turns off in approximately 10 µs | Retry the set “Retry Count” times. Turn off NGDO if fault persists. For example, Retry Count = 2 |
Over-temperature Protection | Temperature at the sense point exceeds the cut-off value. | NGDO turns off in approximately 10 µs | Wait for the temperature to fall below the Restart value. Turn on NGDO. |
When any of these fault conditions occur, detach and the reattach the USB type-C cable to reestablish the contract. To always retry, make the Retry Count as 255.
The following table lists the PAG1 source-side fault conditions and their detection pins:
Fault Condition | Detection Pin |
Input Undervoltage | VDDD700 |
Input Overvoltage | VDDD700 |
Overcurrent | CS |
Secondary Over Voltage | OVP_AUX |
Figure 2. Flyback converter circuit with Cypress’s primary side controller PAG1P
See the following table for PAG1 source-side protection flow of events. See the PAG1P Primary Side Start up Controller datasheet for details.
Protection Feature | Fault Event | Immediate Protective Action | Post-Fault Behavior |
Undervoltage Protection | VDD falls below 90 V. (debounce = 30 ms) | Gate pulses are turned off. | Auto-restart if VDD700>100 V. PAG1P will wait TAR seconds before a soft start. This sequence is repeated three times. |
Overvoltage Protection | VDD rises above 448 V. | Gate pulses are turned off. | Auto-restart if VDD<445 V. PAG1P will wait TAR seconds before a soft start. This sequence is repeated thrice. |
Overcurrent Protection | When the CS pin voltage exceeds V_CSTH1 = 0.5 V. | Limits the primary current by turning OFF the primary FET. | Output voltage falls. Delivers limited power because of limited duty (for closed loop) and auto restarts (for open loop) |
Secondary Overvoltage Protection | OVP_AUX pin voltage exceeds 1.2 V. (blanking time=2 us) | Gate pulses are turned off. | Auto-restart if OVP_AUX < 1.2 V |