TPD3S714-Q1: power consumption design questions

user4979899

Expert 3080 points

Part Number: TPD3S714-Q1

Hi Sir,

I have some questions about power consumption and behavior need your help to clarify it.

Could you please help on below questions?

- When system is in sleep mode(turn off VIN 3P3 supply), will find there is a current draw from VBUS_CONN.

1. Can EN_N disable VBUS_CON to reduce power consumption ?

2. Is EN_N function workable when VIN 3P3 off ?

3. The system doesn’t need 5V from external and we only need VDP/VDN ESD protection function.

Can we just leave VBUS_CON/VBUS_SYS/FLT_N pin as floating?

over 6 years ago

0 Michael Tan over 6 years ago

TI__Expert 8420 points

Hi,

Thanks for your question on TPD3S714-Q1, We will reply your question soon.

0 user4979899 over 6 years ago in reply to Michael Tan

TI__Expert 3080 points

Hi Michael,

waiting for your feedback.

And add one more questions as item 4.

- When system is in sleep mode(turn off VIN 3P3 supply), will find there is a current draw from VBUS_CONN.

1. Can EN_N disable VBUS_CON to reduce power consumption ?

2. Is EN_N function workable when VIN 3P3 off ?

3. The system doesn’t need 5V from external and we only need VDP/VDN ESD protection function.

Can we just leave VBUS_CON/VBUS_SYS/FLT_N pin as floating?

4. After removing R824(disconnect VBUS_CON),

We find it also has current draw from FLT_N(low level) when our device is in sleep mode(turn off VIN 3P3 supply)

Is ok if we disconnect VBUS_CON and FLT_N as below ?

0 Michael Tan over 6 years ago in reply to user4979899

TI__Expert 8420 points

Hi Anne,

You can find my comment as below :

1. Can EN_N disable VBUS_CON to reduce power consumption ? --> Yes, it can .

2. Is EN_N function workable when VIN 3P3 off ? It can work if VIN 3P3 off.

3. The system doesn’t need 5V from external and we only need VDP/VDN ESD protection function.

Can we just leave VBUS_CON/VBUS_SYS/FLT_N pin as floating?--> You can leave the VBUS_CON and FLT_N floating but the VBUS_SYS should connect to the 5V for internal logic circuit bias and power supply.

4. After removing R824(disconnect VBUS_CON),

We find it also has current draw from FLT_N(low level) when our device is in sleep mode(turn off VIN 3P3 supply)

Is ok if we disconnect VBUS_CON and FLT_N as below ? --If you don't use th FLT_N signal you can leave it floating. You SCH is OK .

0 user4979899 over 6 years ago in reply to Michael Tan

TI__Expert 3080 points

Hi Michael,

Thanks for your feedback. But I don’t fully understand the state of FLT_N.

Is the state of FLT_N related to VBUS_CON only ?

Base on below connection. We measured voltage of pins as below table.

Voltage Condition
VBUS_CON (Floating)	VBUS_SYS	EN_N	VIN	FLT_N (pull high 10M to 5V)	Note
4.94	4.94	GND	3.28	4.53	DUT is active
4.94	4.94	floating	3.28	4.53	DUT is active, but can't read USB port
0	4.96	GND	0	0	DUT is in sleep mode(turn off VIN 3.3V supply)
0	4.94	4.94	3.28	0	DUT is active, but can't read USB port

0 user4979899 over 6 years ago in reply to user4979899

TI__Expert 3080 points

Hi Michael,

Could you please help on it?

Thanks

0 Michael Tan over 6 years ago in reply to user4979899

TI__Expert 8420 points

Hi Anne,

Sorry for mistake.

The VBUS_CON should add a 1uF cap to GND.

The device will detect the VBUS_CON pin voltage once enable. If the VBUS_CON low than Vshrt(125mV) threshold. The FAUL will assert .

You can refer to the datasheet 8.3.2

0 user4979899 over 6 years ago in reply to Michael Tan

TI__Expert 3080 points

Hi Michael,

My question is when I leave VBUS_CON as floating and connect FLT_N to Vbus_sys with 10M ohm resistor,

Then I measure the FLT_N & VBUS_CON as below condition 1/2/3/4.

Item1: IC enable and VBUS_CON is floating. Why VBUS_CON is 4.95V and IC releases FLT_N to HIGH ?

Item3: When VIN is off, IC detects it and releases FLT_N to LOW while enabled.

	What we setting			Measurement Result
Item	VBUS_SYS	EN_N	VIN	FLT_N (pull high 10M to 5V)	VBUS_CON (Floating)	Note
1	4.95	GND	3.28	2.6	4.95	DUT is active
2	4.95	floating	3.28	2.6	4.95	DUT is active, but can't read USB port
3	4.97	GND	0.65	0	0	DUT is in sleep mode(turn off VIN 3.3V supply)
4	4.95	4.95	3.28	0	0	DUT is active, but can't read USB port

0 Michael Tan over 6 years ago in reply to user4979899

TI__Expert 8420 points

Hi Anne,

Item1: IC enable and VBUS_CON is floating. Why VBUS_CON is 4.95V and IC releases FLT_N to HIGH ?

--> What is your mean VBUS_CON floating ? It should have 5V in VBUS_CON after you add 1uF in this pin. The FLT will not assert as this is an normal operation.

Item3: When VIN is off, IC detects it and releases FLT_N to LOW while enabled.

--> In your itme3 , The BUS_SYS is OV , the whole device is power off, the FLT should be low.

0 user4979899 over 6 years ago in reply to Michael Tan

TI__Expert 3080 points

Hi Michael,

We don't add 1uF in the VBUS_CON so we just leave it as floating, and you think the behavior of VBUS_CONN and FLT_N is fine?

And the voltage of FLT_N = 2.6V in item1 & 2 are correct?

Thanks

0 Michael Tan over 6 years ago in reply to user4979899

TI__Expert 8420 points

Hello Anne,

Pls. make sure every thing you setup is correct . I can't give any comment in your wrong setup result.

First, don't let VBUS_CON flaoting.

Second, use 10K resistor pull up to VBUS_SYS.

If you don't add the 1uF cap in the VBUS_CON , the FLT will not be set low once device enable.

The item 1 and 2 is the wrong pull up resistor value , pls use the 10K resistor then your result should be 5V.

0 user4979899 over 5 years ago in reply to Michael Tan

TI__Expert 3080 points

Hi Michael,

Follow your connection(add 1uF cap in VBUS_CON , use 10K ohm pull up for FLT_N) as below diagram.

For Item1, why VBUS_CON is 4.94V and FLT_N is high when VBUS_CON is floating with 1uF to GND ? We can’t find the result that meets Vbus logic table.

For Item3, when our device is in sleep mode, we only turn off VIN, NOT VBUS_SYS. VBUS_SYS is always on. Does this IC release FLT_N to LOW if VIN is off ?

	Voltage Condition
Item	VBUS_CON (Floating) (add 1uF)	VBUS_SYS	EN_N	VIN	FLT_N (pull high 10K to 5V)	Note
1	4.94	4.94	GND	3.28	4.94	DUT is active
2	4.94	4.94	floating	3.28	4.94	DUT is active
3	0	4.96	GND	0	0	DUT is in sleep mode(only turn off VIN 3.3V supply; VBUS_SYS is always on)
4	0	4.94	4.94	3.28	0	DUT is active, but can't read USB port

0 Michael Tan over 5 years ago in reply to user4979899

TI__Expert 8420 points

Hi Anne,

Sorry for the late response!

For the item 1 , the behavior with in SPEC. I highlight the behavior below to the yellow row.

For the Sleep mode, we don't suggest to set the VIN to low , as this pin supply power for the DP/M OVP . You can refer to datasheet 10.2 as below.

In you test the Vin=0V , the FLT be assert , device detect the OVP behavior in the DP/DM . The reason is you haven't put supply for this pin.

0 Michael Tan over 5 years ago in reply to user4979899

TI__Expert 8420 points

Hi Anne,

Sorry for the late response!

For the item 1 , the behavior with in SPEC. I highlight the behavior below to the yellow row.

For the Sleep mode, we don't suggest to set the VIN to low , as this pin supply power for the DP/M OVP . You can refer to datasheet 10.2 as below.

In you test the Vin=0V , the FLT be assert , device detect the OVP behavior in the DP/DM . The reason is you haven't put supply for this pin.

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TPD3S714-Q1: power consumption design questions