UCC3800: How to design a UCC3800-based open-loop fixed-cycle flyback power supply

April 29, 2019, 10:29 pm

≫ Next: TPS23751: Aux power issue

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Part Number:UCC3800

Dear seniors,

I want to use UCC3800 to make a 2W flyback power supply.

Because the input voltage range is narrow, about 11.5V~12.5V, and the output voltage is 14V~16V, the accuracy is not high.

However, due to the small size requirements of the power supply, the efficiency requirements are high.

Therefore, I want to make a flyback power supply with a fixed duty cycle.

I looked at the UCC3800 application manual and the schematic diagram of the flyback power supply with closed-loop optocoupler feedback.

How can UCC3800 be wired to achieve open loop duty cycle, preferably the maximum bearer ratio output?

Is there a corresponding schematic or application documentation to see?

Thank you.

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TPS23751: Aux power issue

April 29, 2019, 10:59 pm

≫ Next: UCC28951: Controlling duty In voltage control mode-Open loop control

≪ Previous: UCC3800: How to design a UCC3800-based open-loop fixed-cycle flyback power supply

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Part Number:TPS23751

Hello all,

Aux power supply 12v input and want to 12v output, light load is normal, 12v output voltage will drop after loading.

Attachment is schematic,and transformer datasheet.

Thank you.

(Please visit the site to view this file)(Please visit the site to view this file)

UCC28951: Controlling duty In voltage control mode-Open loop control

April 29, 2019, 11:20 pm

≫ Next: BQ24133: 1.6MHz Synchronous Switch-Mode Li-Ion/Li-Polymer Stand-Alone Battery Charger Reference Design

≪ Previous: TPS23751: Aux power issue

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Part Number:UCC28951

Hi,

If we want to operate this IC in open loop and in voltage mode control we will have to connect Rsum resistor to Vref and we are giving constant DC voltage at EA- pin to simulate fixed duty condition. but we are observing that it is either giving 0volt at comp pin (min duty and burst mode) or 5V at comparator pin (full duty 70%).We are getting this transition from min duty to max duty condition with a very small difference between EA- and EA+ (0.1V). So we are not able to control duty in open loop. Please suggest how to do it. Please note we have removed C1 capacitor (parallel cap in compensation circuit on comp pin )and shorted C2 capacitor  (series cap in compensation circuit on comp pin )also to make it work like a traditional error amplifier.

Regards,

Jyoti

BQ24133: 1.6MHz Synchronous Switch-Mode Li-Ion/Li-Polymer Stand-Alone Battery Charger Reference Design

April 29, 2019, 11:25 pm

≫ Next: UCC38085: SETTING VALUE OF RSET (pin 2)

≪ Previous: UCC28951: Controlling duty In voltage control mode-Open loop control

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Part Number:BQ24133

Document tidr037, Schematic/Block Diagram,  is missing most of its pages, only last two pages left. Do you have the complete document?

UCC38085: SETTING VALUE OF RSET (pin 2)

April 29, 2019, 11:28 pm

≫ Next: BQ24780S: BQ24780S Query related

≪ Previous: BQ24133: 1.6MHz Synchronous Switch-Mode Li-Ion/Li-Polymer Stand-Alone Battery Charger Reference Design

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Part Number:UCC38085

Hi FORUM.

I am now working on a DC-DC converter using the 38085 but there are a couple of things in the Data sheet which are not very clear to me.

The value of this resistor is found from the Formula  on the image.
I'm not too clear on how to derive :RAMP VOLTAGE HEIGHT"  ?
Is this the peak voltage developed across the current sense resistor?  or something else.

Thanks

Julian

BQ24780S: BQ24780S Query related

April 30, 2019, 12:11 am

≫ Next: TPS53355: Phase Margin and Gain Margin

≪ Previous: UCC38085: SETTING VALUE OF RSET (pin 2)

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Part Number:BQ24780S

Hi Sir,

We are using BQ24780S-EVM for our smart Battery testing.

In this, we have connected the board to 19V and 3.3V Power Supply but we could not charge the battery.

Issue:

We Have connected the EVM to the power supply with Necessary Jumper Settings. When the supply Voltage is given ACDET value is above  2.5V but the ACOK signal is not pulled high and the LED is not Glowing. We Have Also measured the REGN Voltage which is 0V when the Supply voltage is given to the board. The Impedance Occurs the VREGN and Ground is found to be 8.93Kilo Ohm.

Is the measured Impedance Value is Acceptable and what steps could be taken to make the board function properly?

Regards

ANANDAN N

TPS53355: Phase Margin and Gain Margin

April 30, 2019, 12:14 am

≫ Next: TPS23756: TPS23756 circuit

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Part Number:TPS53355

Dear Team,

If I want to measure the phase margin and gain margin for the below circuit, how to modify the circuit?

Is change the R450 to 10 ohm ?

BTW, is this one need to measure the gain margin and phase margin?

BR

Kevin

TPS23756: TPS23756 circuit

April 30, 2019, 12:23 am

≫ Next: What should we promote to customer as they require HV-buck(370Vdc input, 110Vdc/1A output)

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Part Number:TPS23756

Hi Team,

Would you help review our customer schematic and feedback if any comments? thanks. 

Thanks & Regards

Eddie(Please visit the site to view this file)

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What should we promote to customer as they require HV-buck(370Vdc input, 110Vdc/1A output)

April 30, 2019, 12:37 am

≫ Next: TLC59108: What's the difference between output current error & threshold current for error detection (TLC59108)

≪ Previous: TPS23756: TPS23756 circuit

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What should we promote to customer as they require HV-buck(370Vdc input, 110Vdc/1A output)

TLC59108: What's the difference between output current error & threshold current for error detection (TLC59108)

April 30, 2019, 1:48 am

≫ Next: BQ24171: May BQ24171 can use in charger 4V Battery?

≪ Previous: What should we promote to customer as they require HV-buck(370Vdc input, 110Vdc/1A output)

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Part Number:TLC59108

Hi,

May I know what's the difference between output current error and threshold current for error detection on TLC59108?

Thanks,

Christina

BQ24171: May BQ24171 can use in charger 4V Battery?

April 30, 2019, 1:50 am

≫ Next: TPS65094: The Jitter issue of TPS650942 VCGI power rail(Buck 2)

≪ Previous: TLC59108: What's the difference between output current error & threshold current for error detection (TLC59108)

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Part Number:BQ24171

Hi Sir 

May BQ24171 can use in charger 4V Battery? 

if yes, we currently battery pack is use bq28z610.((gauge set 4V to be battery full)

But BQ24171 will going to Blinking at 0.5 Hz when Battery is 4V. 

Is something we need to notice?

                                                              Bogey

TPS65094: The Jitter issue of TPS650942 VCGI power rail(Buck 2)

April 30, 2019, 1:57 am

≫ Next: TPS2546: IEC 62368-1 specification

≪ Previous: BQ24171: May BQ24171 can use in charger 4V Battery?

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Part Number:TPS65094

Dear Sir,

I am Alec Chen form WT and our customer is currently using TPS650942 in their design(please see the schematic as below). And we discover that the Jitter for the Buck 2(VCGI) power rail is over RD's spec (within 25%) . Please also see the Jitter waveform that we measure shown as below. The first one is the 4A load waveform and sec one is the 21A(max load). We check TPS650942's spec and it seems that there are not much that we can change to improve the Jitter . Therefore , Could you kindly give us some advice about improving the Jitter issue? Thanks in advance

Above, please kindly help us and thank in advance. if there is any question,please feel free to contact with me

Cheers

Alec

TPS2546: IEC 62368-1 specification

April 30, 2019, 2:16 am

≫ Next: CC & CV tracking IC for Laser diode driver power supply.

≪ Previous: TPS65094: The Jitter issue of TPS650942 VCGI power rail(Buck 2)

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Part Number:TPS2546

Dear sir,

Our customers want to know if the TPS2546 has a specification that complies with IEC 62368-1?

Would you please help to answer? Thank you very much.

CC & CV tracking IC for Laser diode driver power supply.

April 30, 2019, 2:19 am

≫ Next: TPS53015: What does it mean about the EN of TPS53015

≪ Previous: TPS2546: IEC 62368-1 specification

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Hi,

I am searching a Texas IC, which I would be used for Laser Diode driver power (Isolated) supply

It should have a provision to provide the external reference voltage to track the constant voltage and constant current. In my design I would like to control the Laser diode current and voltage using Digital control

techniques. So can you please suggest any part number which would opted for the specified application.

It would be great, if you provide the part # with other features like Remote ON/OFF, Over voltage protection,Over current protection and Thermal shutdown.

I am trying to find. Please support.

TPS53015: What does it mean about the EN of TPS53015

April 30, 2019, 2:25 am

≫ Next: LM5116: IC power dissipation (real power dissipation vs webench)?

≪ Previous: CC & CV tracking IC for Laser diode driver power supply.

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Part Number:TPS53015

Hi team,

What does it mean about the EN of TPS53015, whether all EN voltage above 1.6v can enable here? Thanks.

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LM5116: IC power dissipation (real power dissipation vs webench)?

April 30, 2019, 2:26 am

≫ Next: BQ25713: Boost mode

≪ Previous: TPS53015: What does it mean about the EN of TPS53015

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Part Number:LM5116

Team,

Looking at the below webench design :
LM5116MHXNOPB ‑ Vin: 36V-57V , Vout: 24.00V @ 2.8A
https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=D17CD48FC65A0A86

The IC power consumption from the power tab is more than 1 W.
-Is it correct? (as it seems significant, even more than the FET loss)

-Is the Webench PCB design taking into account the thermal to be sure that the junction temperature will not exceed the limit?

-Is the webench schematics taking into account accordingly the VCCX input for the internal LDO supply?

Thanks in advance,

A.

BQ25713: Boost mode

April 30, 2019, 2:42 am

≫ Next: BQ34110: Facing issue on Data Flash Access Commands to Change the Operation Config A

≪ Previous: LM5116: IC power dissipation (real power dissipation vs webench)?

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Part Number:BQ25713

Hi,

We use BQ25713RSNR to charge a 2-cell battery.

Situation and Phenomenon:
Boost mode,VBUS 5V,VBAT 7.4V
We measure the boost-mode MOSFET Gate drive signal.
CH3: Highside Vgs(Q209)
CH1: Lowside Vgs
Vgs(th)=1V (Min.)
Low side MOSFET rise over Vgs(th) before highside fall bellow Vgs(th);
High side fall slowly, and there is a step when falling down.There is risk that the Vin may be shorted to Ground.

Question:

Please help refer to the attached schematic and test result and check if they are OK.

(Please visit the site to view this file)

Thanks

BQ34110: Facing issue on Data Flash Access Commands to Change the Operation Config A

April 30, 2019, 2:51 am

≫ Next: BQ25713: IIC

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Part Number:BQ34110

Hi Team TI,

We are trying to write Design Capacity in Data Memory using Advanced communication I2C as explained in the manual slua790.pdf (Page No. 8 & 9).

/cfs-file/__key/communityserver-discussions-components-files/196/6237.slua790.pdf

Our Battery pack Design Capacity is 6000mAH.

We are using BQSTUDIO test (1.3.90 BUILD1) and Updated the EV2400 firmware with the latest version (v0.28 REV 1) from TI website.

So,  We followed the below procedure to write design capacity as mentioned on the reference manual.

       1. Start Register 3E, Bytes to Write F5 41 (data flash address)

       2. Start Register 40, Byte to Write 70 17 (new data)

       3. Start Register 60, Byte to Write 42 (checksum)

       4. Start Register 61, Byte to Write 06 (length of data written)

Data is Writing Successfully. But when we read back the registers it is showing the old Data.

Suggest us how to write the values into Data Memory.??

BQ25713: IIC

April 30, 2019, 2:52 am

≫ Next: BQ27Z561: Recommend wirless charging module and architecture overview for TI Video Doorbell design

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Part Number:BQ25713

Hi

I find in the BQ25713 datasheet the IIC clock frequency is recommended 100KHz max.
But IIC clock frequency can be up to 400KHz in fast mode.In fact we use 600KHz to drive the IIC line and it seems OK.
Could you help check the clock frequency 400KHz or 600KHz is OK?

Thanks

BQ27Z561: Recommend wirless charging module and architecture overview for TI Video Doorbell design

April 30, 2019, 3:17 am

≫ Next: UCC2818: Difference between UCC2818 and UCC28180 PFC controller

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Part Number:BQ27Z561

Hi, 

Can anyone recommend any options for wireless charging components that I can integrate into the TI CC3200 Video Doorbell reference design architecture provided within the below link?

http://www.ti.com/solution/video_doorbell_baby_monitor