LR9500

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

6 of 6

www.unisonic.com.tw

QW-R102-083.a

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CAPACITOR CHARACTERISTICS

The LR9500 is designed to work with ceramic capacitors on the input and output to take advantage of the

benefits they offer. For capacitance values in the range of 0.47 μF to 4.7 μF, ceramic capacitors are the smallest,

least expensive and have the lowest ESR values, thus making them best for eliminating high frequency noise. The

ESR of a typical 0.47 μF ceramic capacitor is in the range of 20 mΩ to 40 mΩ, which easily meets the ESR

requirement for stability for the LR9500.

The temperature performance of ceramic capacitors varies by type and manufacturer. Most large value ceramic

capacitors (≥ 2.2 µF) are manufactured with Z5U or Y5V temperature characteristics, which results in the

capacitance dropping by more than 50% as the temperature goes from 25°C ~ 85°C.

A better choice for temperature coefficient in a ceramic capacitor is X7R. This type of capacitor is the most stable

and holds the capacitance within ±15% over the temperature range. Tantalum capacitors are less desirable than

ceramic for use as output capacitors because they are more expensive when comparing equivalent capacitance and

voltage ratings in the 0.47 μF to 4.7 μF range.

Another important consideration is that tantalum capacitors have higher ESR values than equivalent size ceramics.

This means that while it may be possible to find a tantalum capacitor with an ESR value within the stable range, it

would have to be larger in capacitance (which means bigger and more costly) than a ceramic capacitor with the

same ESR value. It should also be noted that the ESR of a typical tantalum will increase about 2:1 as the

temperature goes from 25°C down to −40°C, so some guard band must be allowed.

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NO-LOAD STABILITY

The LR9500 will remain stable and in regulation with no external load.

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ENABLE CONTROL

The LR9500 may be switched ON or OFF by a logic input at the ENABLE pin. A high voltage at this pin will turn

the device on. When the enable pin is low, the regulator output is off and the device typically consumes 3nA.

output permanently on. In this case the supply voltage must be fully established 500 μs or less to ensure correct

operation of the startup circuit. Failure to comply with this condition may cause a delayed startup time of several

seconds.

swing above and below the specified turn-on/off voltage thresholds listed in the Electrical Characteristics section

UTC assumes no responsibility for equipment failures that result from using products at values that

exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or

other parameters) listed in products specifications of any and all UTC products described or contained

herein. UTC products are not designed for use in life support appliances, devices or systems where

malfunction of these products can be reasonably expected to result in personal injury. Reproduction in

whole or in part is prohibited without the prior written consent of the copyright owner. The information

presented in this document does not form part of any quotation or contract, is believed to be accurate

and reliable and may be changed without notice.