Part Number: TAS5634
My customer encountered problem below while performing output power measurement:
Setting : PVDD=58.5V, Rosc=30kohm
3 ohm load : Vout about 27Vrms, /OTW & /Fault are activated
4 ohm load : Vout about 28Vrms, /OTW & /Fault are activated
5 ohm load : Able to achieve Vout about 50Vrms, /OTW is activated at low Vout too but /Fault remain high.
1) Why /OTW is activated at low output?
2) Why /Fault is activated for 3 & 4 ohm load?
BTL mode: (5 ohm load)
Abnormal output signal when output power exceeds 120W
Question : What is the possible cause?
Additional info : Customer is using their current design of TAS5624A circuitry and replace the IC by TAS5634 with surrounding components' value as stated in datasheet.
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In reply to Adam Sidelsky:
Please refer to attachment for the construction and inductor's specs.
Construction & Specs.xlsx
"Higher load of 5 ohm requires PVDD to be lowered. With 30k ROC, PVDD in 5 ohm case should be max 53V, at 27k ROC, up to 56.5V PVDD can be used with 5 ohm."
==> Customer actually wants to achieve output power with PBTL 3ohm load and BTL 5ohm load as stated in datasheet at PVDD 58.5V.
==> Using higher load (4 & 5 ohm) at PBTL just to verify the shutdown symptom.
==> Originally Roc=27k is used and it seems not much different result compared to 30k.
Do inform if you need more info.
In reply to Wee Keat Chin:
We used the EVM to verify the output power and below are the results:
1) PBTL (3 ohm ): Result is OK. Can achieve output power (>600W) at PVDD=58V, Vo=43.5Vrms
2) BTL (5 ohm): At 58V, there is noise observed as below (signal is not clipped) [This is similar waveform, the actual waveform I took in my hp seems missing. If you need, I need to ask customer to measure again]
So the noise disappeared when the PVDD is reduced to 54V(signal clipped as normal, Vo=37V), however, we can't achieve the desired output power due to lower PVDD.
And we also encountered the DC power supply (equipment) is shutdown(overload) when we tried to increase the Vo.
[eg. at PBTL mode, further increase the gain to get THD 30%. Same phenomena occurred for BTL mode]
We check the current at the DC power supply, there is only drain about 14A. The equipment current capability is 60A max.
Please advise for this phenomena and the noise.
After that, customer may study using their own PCB.
Please advise for this phenomena and the noise. After that, customer may study using their own PCB.
Below is the waveform for the PWM signal before the output filter and Vout (CH3&4 is PWM before coil) when the Damp shutdown.
Customer still yet to decide the output power target, however they may study to drive the IC at typical PVdd =>about 58.5V, THD=30%, Load=3 ohm(PBTL) & 5ohm(BTL).
Customer is checking the output power performance based on datasheet specification which is guaranteed by TI.
Refer to the 5ohm data provided by TI, it mentions that 'Typical 58V PVDD is not supported at 5Ohm BTL'.
If customer wants to use 58V@5ohm load [due to sharing of power supply to PBTL & BTL IC], could you advise what is the maximum output power can be achieved at 30% THD?
Can Roc be reduced to 25k in order to achieve higher current?
Also do you have any idea about the shutdown of the power supply during increment of Vo?
I am little bit confused with your explanation compared to the datasheet information.
For PBTL: Datasheet (pg 9) stated that RL = 3 Ω, 10% THD+N, PVDD=58.5V can achieve 600W.
Question: Is this setting feasible for actual design or PVDD=58.5V is not recommended (must be lower)?
For BTL : Understood that lower PVDD is needed if 5 ohm load used. So based on the 5 ohm Data provided, with PVDD=56V & Roc=27k , the device can achieve 315W 10% & peak power 440W 30%.
Question: i) Is this a feasible design? Or PVDD= 56V is not recommended (must be lower) ?
ii) Customer target is 350W at 10%THD. Can Roc be reduced (eg. 25k ohm used) in order to achieve higher output power?
Hope to get clarification from you.
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