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TLV1117: Output capacitor of TLV1117

Part Number: TLV1117

Dear all,

Our customer is considering using TLV1117.
According to the data sheet, it is described that an electrolytic capacitor having an ESR of 0.2Ω to 10Ω is used for stable operation as follows.

However, our customers are considering using low ESR ceramic capacitors (connecting ESR resistors in series) to the output capacitor from the viewpoint of life, size and cost.
Could you tell me the following contents?
1. When a low ESR ceramic capacitor is connected to the output capacitor (an ESR resistor is connected in series),

is the required capacitance for stable operation about 100 μF as shown in the following circuit diagram?


2. Regarding the resistance value of the ESR connected to the ceramic capacitor, is it necessary to set the resistance to 0.2 to 10Ω as described in the data sheet together with the ESR of the ceramic capacitor in order to stabilize the operation?

Best Regards,

Y.Ottey

  • Hi Y.Ottey,

    For question #1. a common trick employed with using ceramic capacitors is to add a series resistor of ~1-Ohm. Most 1117's recommend a minimum capacitance of 10uF (while not explicitly stated on the TLV1117 datasheet). 100uF is commonly used as this is much more stable. Note: the regulator sees the total ESR if multiple capacitors are used at the output.

     

    For Question #2: Yes, as answered above.

    We have created a next-generation version of this that is much better all around. The TLV767 has the following improvements:.

    1. Ceramic capacitor stable only 1uF required

    2. Much lower Iq 50uA vs the 5mA of a 1117

    3. No minimum load current (10mA for a 1117)

    4. Superior Inrush control

    5. Fold-back current limiting

    I hope this helps.