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# TLV743P: The IQ LDO

Part Number: TLV743P
Other Parts Discussed in Thread: TL1963A, TLV767-Q1

Hi

The smart door lock project requires low-power LDO, please help to recommend the following selection, thank you!

The main parameter requirements are as follows:
1. Static power consumption: not more than 2Ua.
2. Input voltage: above 8V.
3. Output current: 1A.
4. Output voltage: 3.3V fixed or adjustable.
5. Vdrop is less than 900mV

Regards,

Charlie

• Hi Charlie,

Regarding static power consumption, are you referring to ground current at full load or no load?

Based on the other requirements, I would recommend a DC/DC converter to lower Vin as thermals here could be problematic.

Erin

• Hi Erin,

Under the working condition of Vin=8V, Vout=3.3V, Iout=1A, the efficiency of LDO is only 41.25%, and the power loss of LDO is 4.7W.

Can LDO products withstand such heat? How many watts can a general LDO withstand? Thanks.

Regards,

Charlie

• Hi Erin,

Do we have LDO products that can meet customer needs? Dissipated power greater than 4.7W. Thanks.

Regards,

Charlie

• Hi Charlie,

LDOs can typically handle around 1W, thermal shutdown is typically ~160°C. Given the thermal resistance of most of our devices, this is risky. TLV76733QWDRBRQ1 or TL1963A-33DCQT would work here if Vin was lower.

Power Dissipation (PD) = (8-3.3) * 1 = 4.7 or PD = (5-3.3) * 1 = 1.7

TL1963A:

Junction Temperature (TJ) = Ambient Temperature (TA) + (50.5 * 4.7) = 244°C/W + TA → thermal shutdown

or TA + (50.5 * 1.7) = 85.85°C/W + TA

TLV767-Q1:

TJ = TA + (51.9 * 4.7) = 243.93 °C/W + TA → thermal shutdown

or TA + (51.9 * 1.7) = 88.23°C/W + TA