TPS51220A: V5SW

Shota Mago

Expert 8110 points

Part Number: TPS51220A
Other Parts Discussed in Thread: TPS51220

Hi team,

My customer will use 2pcs of TPS51220A for their application with following usage.

Usage1:

VIN：13V~18V
Vout1：4.57V
Vout2：3.3V

Usage2:

VIN：13V~18V
Vout1：12V
Vout2：5V

Questions

Datasheet page 9 shows that "When EN1 is high, PGOOD1 indicates GOOD and V5SW voltage is higher than 4.8 V, switch-over function is enabled. When switch-over is enabled, VREG5 output voltage is approximately equal to the V5SW input voltage."
What is reason to switch to VREG5=V5SW ?(Because generating 5V using LDO from VIN cause heating?)
Like Usage1, if the application does not generate 5V, can this V5SW be OPEN?
Like Usage2, in case of generating 5V from Vout2, is it okay to connect Vout2(5V) to V5SW?
Or should 5V be generated from Vout1?

Best regards,

Shota Mago

over 5 years ago

0 Yuchang Zhang over 5 years ago

TI__Mastermind 18510 points

Mago,

1, switchover is for improving eff to save power.

2, if no proper input, let it floating

3, suggest channel1 with 5Vout

Yuchang

0 Shota Mago over 5 years ago in reply to Yuchang Zhang

TI__Expert 8110 points

Hi Yuchang,

Thanks for your quick reply.

Regarding 1, could you provide how much power consumption can be saved using V5SW comparing to Vin=18V?

Regarding 3, Is channel1 with 5Vout must requirement? Or just nice to have?

The customer would like to keep channel2 5Vout since it needs tedious layout modification.

Best regards,

Shota Mago

0 Yuchang Zhang over 5 years ago in reply to Shota Mago

TI__Mastermind 18510 points

Hi, For 1, I have no data, you know if from Vin the power loss will be (Vin-5)*IV5REG, current depends on customer appreciation use.

For 2, need use Channel1 for 5Vout if with switchover functions.

Yuchang

0 Shota Mago over 5 years ago in reply to Yuchang Zhang

TI__Expert 8110 points

Hi,

Sorry, I forgot to add current information on VREG5.

VREG5 is just connected to 10uF capacitor and it doesn't drive any load.

So I think output I5VREG depends on current of gate driver and other internal analog components.

Datasheet page 5 shows that I(V5SW) is 1.4mA in case of TRIP=0.

Is I5VREG roughly equal to 1.4mA if switchover is disabled and VREG5 doesn't drive external load?

Best regards,

Shota Mago

0 Yuchang Zhang over 5 years ago in reply to Shota Mago

TI__Mastermind 18510 points

Hi,

I haven't found 1.4mA data in 51220A DS, but based on your description, if you don't use the LDO for system power source with some loading, only IC internal logic will use it with small current. generally it is below 10mA or around 10mA.

Yuchang

0 Shota Mago over 5 years ago in reply to Yuchang Zhang

TI__Expert 8110 points

Hi,

Sorry, I referred to TPS51220's DS not TPS51220A by mistake.

Thanks for your answer.

Best regards,

Shota Mago

Power management

Power management forum

TPS51220A: V5SW