Dear supporter
From TPS23881 datasheet the register 0x27 and 0x28 are for priority setting for four channels.
The datasheet said "OSS Code for Channel Off"
But I don't know what OSS code is ? how to produce a OSS code ? write OSS code to where(register?) to channel off.
Hello Minghao,
The OSS pin is an input pin for TPS23881 which can be used to quickly shutdown channels based on port priorities. You can configure TPS23881 to accept either single-bit OSS shutdown codes or multi-bit OSS shutdown codes.
Single-bit priority:
To use single-bit priority, set MbitPrty = 0 in register 0x17. This mode lets you set channels as low or high priority only. To configure channels as low or high priority, set bit fields OSS4-OSS1 in register 0x15. When the OSS pin goes high, this triggers shutdown and only low priority ports are turned off.
Multi-bit priority:
To use multi-bit priority, set MbitPrty = 1 in register 0x17. This mode gives you more priority options by assigning each channel a 3-bit priority code. Please see Table 42 where it describes the configuration needed for registers 0x27 and 0x28 to set this priority code of each channel using the MBPn bitfield.
The timing diagram shown below with bits SC 2, SC 1, SC 0 correspond to OSS[2:0] bits in Table 42. When a valid multi-bit OSS shutdown code is received on the OSS pin, it will be compared to the priority code of each channel and trigger channel shutdown if shutdown(OSS) code <= priority(MBPn) code of that channel.
When a channel is shutdown, select registers are reset as well and this is described in Table 23. Channel Turn Off with OSS. See Figure 38 of TPS23881 datasheet for 3-bit OSS shutdown code timing diagram.
where the timing values are
The OSS code can be generated by any processor, MCU, or FPGA which allows producing a waveform that meets the timing requirements shown above.
Regards,
Sai Gunda
