MIC5283YML datasheet(9/19 Pages) MICREL

9 / 19 page

Micrel, Inc.

MIC5283

March 2012

M9999-030812-A

Detailed Description

The MIC5283 voltage regulator accepts a 6V to 120V input

voltage and has an ultra-low 8µA typical quiescent current

while offering an excellent line transient response and

PSRR. These features make it ideal for harsh, noisy

environments. All options offer 150mA of output current.

The MIC5283YML and MIC5283YME offer an adjustable

output voltage from 1.22V to 5.5V. The MIC5283-3.3YML

and MIC5283-3.3YME offer fixed 3.3V outputs and the

MIC5283-5.0YML and MIC5283-5.0YME offer fixed 5.0V

outputs. The YME packaged devices feature a heat slug to

more effectively remove heat from the die.

Applications Information

Thermal Protection

The MIC5283 has internal thermal shutdown to protect it

from excessive heating of the die. When the junction

temperature exceeds approximately +155°C, the output is

disabled and the device begins to cool down. The device

turns back on when the junction temperature cools by

15°C. This will result in a cycled output during continuous

thermal-overload conditions.

Current Limit

The MIC5283 features output current-limit protection. The

output sustains a continuous short circuit to GND without

damage to the device, but thermal shutdown often results.

The typical value for the current limit of the MIC5283 is

300mA.

Input Capacitor

Connect a 1.0µF capacitor from VIN to GND. Micrel

recommends

the

C5750X7R2E105M,

1.0µF,

250V

capacitor made by TDK. When using a different capacitor,

assure that the voltage rating of the capacitor has

adequate headroom to withstand any potential transient.

CPSRR Capacitor

To maintain high power supply rejection, connect a 0.1µF

capacitor from CPSRR to GND. The voltage rating of the

capacitor must be at least 14V.

Output Capacitor

Connect a 10µF capacitor from VOUT to GND. Assure that

the voltage rating of the capacitor exceeds the designed

output voltage of the MIC5283.

Output Voltage Setting

For the MIC5283YML and MIC5283YME, VOUT is

programmable from 1.22V to 5.5V using an external

resistive divider. VOUT is set using the following equation:



















REF

OUT

where VREF = 1.22V, and R1 and R2 form the feedback

voltage divider from VOUT to ground.

Thermal Measurements

It is always prudent to measure an IC’s case temperature

to make sure that it is within operating limits, but it is easy

to get erroneous results. The standard thermocouple that

comes with many voltage meters uses a large wire gauge

that behaves like a heat-sink, resulting in artificially low

case temperature measurements. Use a thermocouple of

36-gauge wire or smaller, such as the Omega (5SC-TT-K-

36-36), to minimize the heat-sinking effect. Also, apply a

thermal compound to maximize heat transfer between the

IC and the thermocouple.

An infrared thermometer is a recommended alternative.

The IR thermometer from Optris has a 1mm spot size,

ideal for monitoring small surface mount packages. Also,

the optional stand makes it easy to keep the beam on the

IC for long periods of time.

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