Micrel, Inc.

MIC5206

May 2006

9

M9999-051506

(408) 955-1690

Ultra-Low-Noise Application

Figure 2. Ultra-Low-Noise Fixed Voltage Application

Figure 2 includes a 470pF capacitor for low-noise

operation and shows EN (pin 7) connected to IN (pin 8)

for an application where enable/shutdown is not

required. The error flag is shown with a 47kΩ pull-up

resistor.

Adjustable Regulator Applications

Figure 3 shows the MIC5206BMM adjustable output

voltage configuration. Two resistors set the output

voltage. The formula for output voltage is:

⎟

⎠

⎞

⎜

⎝

⎛

+

×

=

1

R1

R2

1.242V

Resistor values are not critical because ADJ (adjust) has

a high input impedance, but for best results use resistors

of 470kΩ or less. A capacitor from ADJ to ground

provides greatly improved noise performance.

Figure 3. Ultra-Low-Noise Adjustable Voltage Application

Figure 3 also includes a 470pF capacitor for lowest-

noise operation and shows EN (pin 7) connected to IN

(pin 8) for an application where enable/shutdown is not

with a 47kΩ pull-up resistor.

Thermal Considerations

Layout

The MIC5206-x.xBM5 (5-pin SOT-23 package) has the

following thermal characteristics when mounted on a

single layer copper-clad printed circuit board.

Multilayer boards having a ground plane, wide traces

near the pads, and large supply bus lines provide better

thermal conductivity.

PC Board

Dielectric

θ

JA

FR4

220°C/W

Ceramic

200°C/W

SOT-23-5 Thermal Characteristics

The “worst case” value of 220°C/W assumes no ground

plane, minimum trace widths, and a FR4 material board.

The MIC5206-xxBMM (8-pin MSOP) has a thermal

resistance of 200°C/W when mounted on a FR4 board

with minimum trace widths and no ground plane.

PC Board

Dielectric

θ

JA

FR4

200°C

MSOP Thermal Characteristics

Nominal Power Dissipation and Die Temperature

The MIC5206-x.xBM5 at a 25°C ambient temperature

will operate reliably at over 450mW power dissipation

when mounted in the “worst case” manner described

above. At an ambient temperature of 40°C, the device

may safely dissipate over 380mW. These power levels

are equivalent to a die temperature of 125°C, the

maximum operating junction temperature for the

MIC5206.

For additional heat sink characteristics, please refer to

Micrel Application Hint 17, “Calculating P.C. Board Heat

Sink Area For Surface Mount Packages”.