MIC5200 Datasheet, PDF (6/6 Pages) Micrel Semiconductor – 100mA Low-Dropout Voltage Regulator Preliminary Information

MIC5200
Micrel
Ripple
vs. Frequency
100
80
I_L = 100µA
60
40
20
0
Ripple
vs. Frequency
100
80
I_L = 1mA
60
40
20
0
Ripple
vs. Frequency
100
80
I_L = 100mA
60
40
20
0
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
Applications Information
External Capacitors
A 1µF capacitor is recommended between the MIC5200
output and ground to prevent oscillations due to instability.
Larger values serve to improve the regulator's transient re-
sponse. Most types of tantalum or aluminum electrolytics will
be adequate; film types will work, but are costly and therefore
not recommended. Many aluminum electrolytics have electro-
lytes that freeze at about –30°C, so solid tantalum capacitors
are recommended for operation below –25°C. The important
parameters of the capacitor are an effective series resistance
of about 5Ω or less and a resonant frequency above 500kHz.
The value of this capacitor may be increased without limit.
At lower values of output current, less output capacitance is
required for output stability. The capacitor can be reduced to
0.47µF for current below 10mA or 0.33µF for currents below
1 mA. A 1µF capacitor should be placed from the MIC5200
input to ground if there is more than 10 inches of wire between
the input and the AC filter capacitor or if a battery is used as
the input.
The MIC5200 will remain stable and in regulation with no load
in addition to the internal voltage divider, unlike many other
voltage regulators. This is especially important in CMOS RAM
keep-alive applications.
When used in dual supply systems where the regulator load
is returned to a negative supply, the output voltage must be
diode clamped to ground.
Thermal Considerations
Part I. Layout
The MIC5200-xxBM (8-pin surface mount package) has the
following thermal characteristics when mounted on a single
layer copper-clad printed circuit board.
PC Board
Dielectric
FR4
Ceramic
θ_JA
160°C/W
120°C/W
Multi-layer boards having a ground plane, wide traces near
the pads, and large supply bus lines provide better thermal
conductivity.
The "worst case" value of 160°C/W assumes no ground plane,
minimum trace widths, and a FR4 material board.
Part II. Nominal Power Dissipation and Die Temperature
The MIC5200-xxBM at a 25°C ambient temperature will
operate reliably at up to 625mW power dissipation when
mounted in the "worst case" manner described above. At an
ambient temperature of 55°C, the device may safely dissipate
440mW. These power levels are equivalent to a die tempera-
ture of 125°C, the recommended maximum temperature for
non-military grade silicon integrated circuits.
For MIC5200-xxBS (SOT-223 package) heat sink character-
istics, please refer to Micrel Application Hint 17, “Calculating
P.C. Board Heat Sink Area for Surface Mount Packages”.
ENABLE Input
50 mil
The MIC5200 features nearly zero OFF mode current. When
the ENABLE input is held below 0.7V, all internal circuitry is
powered off. Pulling this pin high (over 2.0V) re-enables the
245 mil
150 mil
device and allows operation. The ENABLE pin requires a
small amount of current, typically 15µA. While the logic
threshold is TTL/CMOS compatible, ENABLE may be pulled
as high as 30V, independent of the voltage on V_IN.
30 mil
50 mil
Minimum recommended board pad size, SO-8.
July 1998
3-128