TAS2505-Q1: Unable to get low quiescent current in shutdown mode

Wesley Kerstens1

Part Number: TAS2505-Q1
Other Parts Discussed in Thread: TAS2505, TPS62740

Hi,

We're using the TAS2505 Class-D amplifier in a low power portable device. The speaker will only be used during certain events and will be in low power mode for most of the time.

We were in the assumption that the quiescent current would be <5uA when the RST is pulled low, as shown in this table:

We're however measuring a increase of 85uA when we mount the TAS2505. The TAS2505 is connected to a STM32 microprocessor using I2C and I2S, as shown here:

As you can see we're using the internal LDO to generate AVDD and DVDD.

Can you help us with lowering the quiescent current from 85uA to the specified <5uA?

Thanks.

over 6 years ago

0 Luis Fernando Rodriguez S. over 6 years ago

TI__Guru* 84915 points

Hi, Wesley,

Welcome to E2E and thank you for your interest in our products!

The current values that you mention apply only when the LDO is not being used. As mentioned in section 2.8.1.1.1 Standby Mode ( http://www.ti.com/lit/ug/slau472/slau472.pdf#page=43 ), when the LDO is used and all the blocks are powered down, the system could consume around 100uA (which is a similar value that you are getting).

However, in order to get a standby current of approximately 1.5uA at AVDD (which is the value mentioned in the electrical characteristics) you would need to disable LDO_SEL pin (connected to SPKVSS). See 2.8.1.2.1 Standby Mode section ( http://www.ti.com/lit/ug/slau472/slau472.pdf#page=43 ) for more details.

Please let me know if you have additional questions or comments.

Best regards,
Luis Fernando Rodríguez S.

0 Wesley Kerstens1 over 6 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 60 points

Hi,

Thanks for the reply. We were indeed already suspecting the LDO_SEL. Can we just connect this pin to a MCU IO in a next revision and toggle the pin high when we want the amp enabled? This is just a selection pin, it doens't have any power requirements right?

Regards,

Wesley

0 Luis Fernando Rodriguez S. over 6 years ago in reply to Wesley Kerstens1

TI__Guru* 84915 points

Hi, Wesley,

It is always recommended to connect the LDO_SEL pin to SPKVDD (or IOVDD) instead of a MCU IO. The LDO_SEL pin will deliver the power to both analog and digital power pins. The MCU IO won't be capable to handle all the current amount.

I would suggest to use a voltage-controlled switch in order to connect the SPKVDD or SPKVSS to LDO_SEL pin for your next revision. In that way, you would be able to reduce the current consumption in standby mode.

Best regards,
Luis Fernando Rodríguez S.

0 Wesley Kerstens1 over 6 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 60 points

Hi Luis,

Thanks.

We also have TPS62740 in the design with a integrated loadswitch (max 100mA). We'll use this pin to switch on the TAS2505 LDO.

Regards,

Wesley

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TAS2505-Q1: Unable to get low quiescent current in shutdown mode