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WEBENCH® Tools/LM5122: Is this IC good for 3-44 VDC input to fixed 48 VDC?
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LM2776: LM2776
Part Number:LM2776
hi Team,
I am using LM2776 device to generate Negative 3.3V from +3.3V as Input supply. Both these voltages, +/- 3.3V, is applied as supply voltages of 3 OP-AMP and 1 Instrumentation Amplifier.
But I am getting Positive 0.5V approx at the output of Lm2776 instead of Negative 3.3V. When i am isolating the OP-AMPS and INA, output becomes -3.3V. In D/S max load current is mentioned as 200mA.
I have connected 1uF, with low ESR high stability, across C1 and C2. Also, input and output has 2.2uF in parallel to 0.1uF.
Please let me know of this behavior and any work around possible
Regards,
Vivek
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TPS548B22: VBP = 2.93V for MODE / VSEL / FSEL setting
Part Number:TPS548B22
Hello TI,
We're using TPS548B22 as our DCDC Buck converter solution. Our customer and we have a question regarding the VBP voltage for MODE / VSEL / FSEL setting.
The VBP is 5.07V in normal operation so we are confused why you particularly listed down the Vdetect_th range that calculated with VBP = 2.93V?
We know the controller will detect the external resistor divider ratio during initial power up (VDD = 3 V and VBP = 2.9 V).
It means the table in datasheet page 7 only happens at the moment when BP starts rising from 2.93V to 5.07V.
It looks like an unusual way to get config and we even cannot control VDD / VBP rising time. Or the VBP would keep at 2.93V and wait for all config settle down?
Is it necessary to use different RES divider ratio to get the same target voltage on each pin as page 7 listed ?
Stan.
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High reliability switching regulator with remote sensing feature.
Hi,
Microsemi has strong FPGA products in space grade temperature. Our FPGA has the remote sensing pins for Core voltage and GND. We are looking for a switching regulator with remote sensing feature with High reliability. The Regulator must be sustained in space qualification tests.
If you any parts, please share to us. Once we have tested with our FPGA, it will be suggested to space vendor to use the regulator.
Regards,
Srinivasrao
Senior Hardware design Engg,
Microsemi
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BQ25708: Battery charging in Precharging mode
Part Number:BQ25708
Dear support,
in the datasheet is metioned, that a deeply discharged battery is charged in precharge-mode.
What is the function of "VVBAT_UVLO"? Does the charger tries to charge a battery, if the VBAT is below VVBAT_UVLO?
(see 8.3.1 in datasheet)
In the datasheet (see 8.4.1.2) is a sentence "When battery is full or battery is not in good condition to charge, host terminates charge by setting
REG0x12[0] to 1, or setting ChargeCurrent() to zero"
What is the meaning of "in no good condition to charge"? Is this related to the Vvbat_uvlo?
Does the charger tries to charge the battery, even when it is "in no good condition to charge"?
We have tried to charge a battery with 2.0V (Charger programmed to 3S) and the charger does not enter precharge mode.
Regards,
Volker Placke
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TPS22917: RCB in disable mode
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UCC27714: HB,HS,HO leakage failure
Part Number:UCC27714
Three phase motor 12.5kHz PWM commutation 100VDC cause random failure to HS/HO junction, no signs of under/over shoot HO via soft turn on/off compensation resistors.
The means of using soft or even hard NFET turn on always results with high side Totem pole failing, stresses HS/HO internal NFET. Such results in leaking VS supply onto 1/2 bridge inductor raising typical 12.6v floating bias to nearly 14.3v, e.g. HB leakage via HS/HO breakdown.
Conditions: 80us overlapping PWM drive signals HI/LI inputs, LO/HO:130 ohm GTon, 75 ohm GToff (parallel R/Schottky), NFET Qg=<96NC @VBpin=13.6v
Contrast: Other vendor 600v gate driver (IGPK +/-600/350ma <10us pules) never fail similar described leakage, mandates unwarranted chip replacements.
1. How can maintaining IGPK +/-4amp (<10us pulses) ever cause HO/HS stress via 130 ohm GTon 75 ohm GToff resistor?
2. What is work around to stop HS to HO reverse leakage path from developing in first place, typical HS pin R value?
3. Why does HO/HS leakage path failure cause uncontrolled and very high inductive voltage overshooting?
4. Zener diode (15.2VzMin, 16.4VzMax @10ma) or 20k protection resistor placed across HS/HO, regulates floating VB the cause?
5. Any Wiki report updates how to correct HO side gate drive failures caused from industry typical configurations?
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TPS650830: Long press PWRBTNIN to trigger shutdown
Part Number:TPS650830
Hi,
Based on the setting of FLT bits, we can long press PWRBTN to trigger an emergency shutdown. THe questions are,
- After PWRBTNIN is released, how long it takes to finish an emergency shutdown?
- Will all the register in UVLO domain be set back to default value from emergency shutdown?
- When will the register in RTC domain being reset?
Thanks!
Antony
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TPS65910: Startup waveform overshoot
Part Number:TPS65910
Hi team,
My customer is using TPS65910 as the PMIC of the AM5728. But they have some questions about the startup waveform.
As you could see below waveform, VPLL have the Startup overshoot, same as VDAC, VMMC, VAUX2.
Besides, for the VDD-CORE, it has weird ladder waveform as below.
Could you please help to provide some advice for this? Thanks.
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UCC28061: Applicability Area
Part Number:UCC28061
Hi,
I am a design engineer. I am facing a persistent failure occuring in PFC circuit. We use UCC28061D as a PFC controller. At start-up, UCC28061D get fatal damage accompanied by switching transistor damage in most cases. I am working on 3-phase 115VAC power system with 400Hz. So, my point to ask is that, although shown UCC28061D applications cover one-phase AC power system, is it compatible with working on 3-pHase power system applications? Any recommendation or help is invaluable regarding the area of applicability.
Thanks a lot in advance.
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TPS62130: Inductor for switching sometimes making noise.
Part Number:TPS62130
Hello everyone,
I have a power management circuit, in which the main regulation is done by TPS62130 switching regulator. It converts upto 8.4v of DC supply from a Li-Ion battery pack to 3.7V. Switching frequency is 2.5Mhz.
Here is the schematic of the supporting circuit.
Here are the waveforms at SW pins.
The operation of this circuit is quite smooth overall and I am satisfied with the performance. However, there are a very rare occasions where the inductor (L601) makes a faint high frequency humming noise. Inductor's part no.: 74404043022A (2.2µH Shielded Wirewound Inductor 3.83A 23 mOhm).
This circuit is used to power a GSM module through a load switch (TPS22810) along with other ICs and peripherals.
Can you please tell what could be the reason for this observation? And how do we rectify it?
Thank you.
Regards,
Vivek
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UCC28951: the PSFB can't work using UCC28951 when the output power higher than 1kW
Part Number:UCC28951
Hi,
customer use UCC28951 as phase shift full bridge controller and use UCC21521C as SiC driver, input voltage is 500VDC, output is 27.5V /3kW。
the circuit is refer to datasheet as below show.
The question is that the output will has large ripple when the output power is higher than 1.3kW both in voltage mode and current mode. below is the test waveform of QD.
The yellow is UCC28951 output signal, the green is UCC21521 output signal and the blue is current of inductor.
you can see UCC28951 lost a pulse during the working, which lead to the large ripple on output. if the output voltage higher than 32V, the load will get in to OVP mode, the output voltage will return back to 27.5V.
When the output power is lower than 1kW, this circuit can work properly.
is it may caused by the loop response? could you help give some ideas about it.
many thanks.
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BQ34Z100-G1: RemCap, FullChgCap, TrueRC and TrueFCC
Part Number:BQ34Z100-G1
Please see attached gg and log. Chem ID is 457.
RemCap, FullChgCap, TrueRC, TrueFCC all drop in value during charge when the current is still well above the taper setting (600mA).
At sample 1492, TrueFCC drops from 10120 to 9552 and hold for the duration of the charge
At sample 1493, TrueRC drops from 10105 to 9538, and starts to rise again
At sample 1504, RemCap and FullChgCap both drop from 10119 to 9952 and hold for the duration of the charge.
Any ideas on what setting I have wrong?
Thanks,
Larry Norman
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UCC28180: AC24V Input U
Part Number:UCC28180
Hi Sir:
We have one application for UCC28180 Which Input is AC24V and Output is 60V 2A,
We use Tina II for simulation but output ripple was very bigger ,as attached file(UCC28180-P.TSC) ,would U please review it and give us good suggestion.
Thanks
Gorden
.(Please visit the site to view this file)
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UCC1804: UCC1804
Part Number:UCC1804
Dear SIrs, good afternoon!
Could you help us to clarify if it is acceptable that in microchip UCC 1804J there is bare die (crystal) - UCC 3804? And what is the reason?
We are looking forward to your answer urgently.
SIncerely,
Olesya
Sovtest
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TPS92515: TPS92515: Operation current
Part Number:TPS92515
Hello there
I have to design a standby power consumption optimized design with the TPS92515.
The LEDs are turned off: Vadj is directly tied to Vcc. PWM input is controlled by uC and has a logic level of 0.
So everything is switched off.
My measurements show a power consumption of 4.9mA @24VDC and I can measure a leakage voltage at pin sw= 0.069V
From the datasheet 7.5 -> Electrical characteristics -> System currents
Icq operating current not switching VIADJ=VCC 0.85mA (typ) / 1.5mA (max)
How I can reach a 1.5mA operating current? Do I misunderstand operating current?
Thanks and regards,
Christian
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LM74700-Q1: Spice model LM74700-Q1
Part Number:LM74700-Q1
Hello,
is a spice model for the LM74700-Q1 available?
Regards,
Markus
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TPS3813: Datasheet discrepancy on WDI
Part Number:TPS3813
Team,
The latest datasheet from the T.I. website (July 2016) has the following text at paragraph 8.3.1:
“The TPS3813xxx family of devices have a watchdog timer that must be periodically triggered by either a positive or negative transition at the WDI pin”
However, at the same time at paragraph 8.2, the functional block diagram depicts a rising edge detector attached to the WDI input, which seems disagree with the text at paragraph 8.3.1.
Can you confirm which is correct for this device?
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LM25117: No output, what's different between webench and evm?
Part Number:LM25117
We followed TI webench tool to designed LM25117, input is 18 to 26V and output is 16V/7A. The resault is no output during test, and we found schematic is different between webench and EVM. Could you help me to chech what's wrong value or circuit to let no output?
My schematic:
Webench:
EVM:
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BQ27530-G1: An error in flowchart for programming the chip in production.
Part Number:BQ27530-G1
Hi,
I believe I have found an error in the document "Going to production with BQ275xx..." ( http://www.ti.com/lit/an/slua449f/slua449f.pdf
What I have learned trying to make the chip work, is that if you send data to the chip you are supposed to send it to the registers 0x64 and 0x65, then reading 0x66 to be able to confirm the action wanted. However in this document when trying to erase the IF rows the flowchart tells me to:
sendCommand(0x00,0x03);
sendCommand(0x01,0x00);
sendCommand(0x02,0x00);
sendCommand(0x00,0x00);
sendCommand(0x01,0x01);
Which would mean that the checksum to be written to 0x64 would be 0x04 yet the flowchart claims it should be 0x03, therefore it would seem that the two lines is an error? Furthermore I have found another of your chips equivelant document ( http://www.ti.com/lit/an/slua504a/slua504a.pdf problem with the document is that the checksum isnt even being written to 0x64.
being written. Because I am getting an error when reading from 0x66 and trying to compare it with 0, and i cannot seem to be able to salvage the chip, as it will be stuck in an eternal ROM mode, even when I try to pull it out of rom mode by writing:
sendExtendedCommand(0x00,0x00,0x0f);
sendCommand(0x64,0x0F);
sendCommand(0x65,0x00);
Underneath is a snip of both the flowcharts in question. The first is from the BQ275xx and the second is BQ274xx both on page 9. I have also included a snip of the implementation of the send commands. The timer sleep is in msec. I found that the chip is more responsive if the delay was added.
int sendCommand(uint8_t reg, uint8_t command) {
timer_sleep(5);
uint8_t buffer[2] = { 0x00, 0x00 };
buffer[0] = reg;
buffer[1] = command;
return i2c_write(I2C2, ADDR, sizeof(buffer), buffer);
}
void sendExtendedCommand(uint8_t reg, uint8_t command_MSB,
uint8_t command_LSB) {
uint8_t buffer[3] = { 0x00, 0x00, 0x00 };
buffer[0] = reg;
buffer[1] = command_LSB;
buffer[2] = command_MSB;
i2c_write(I2C2, ADDR, 3, buffer);
}
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