MIC2213_05 Datasheet, PDF (10/11 Pages) Micrel Semiconductor – Sequenced Portable Power Management IC

MIC2213
Input Capacitor
Good bypassing is recommended from input to ground to
help improve AC performance. A 1µF capacitor or greater
located close to the IC is recommended.
Bypass Capacitor
The internal reference voltage of the MIC2213 can be by-
passed with a capacitor to ground to reduce output noise and
increase power supply rejection (PSRR). A quick-start feature
allows for quick turn-on of the output voltage regardless of
the size of the capacitor. The recommended nominal bypass
capacitor is 0.01µF, but it can be increased without limit.
Output Capacitor
Each regulator output requires a 1µF ceramic output capaci-
tor for stability. The output capacitor value can be increased
to improve transient response, but performance has been
optimized for a 1µF ceramic type output capacitor.
X7R/X5R dielectric-type ceramic capacitors are recom-
mended because of their temperature performance. X7R-type
capacitors change capacitance by 15% over their operating
temperature range and are the most stable type of ceramic
capacitors. Z5U and Y5V dielectric capacitors change value
by as much as 50% and 60% respectively over their operat-
ing temperature ranges. To use a ceramic chip capacitor with
Y5V dielectric, the value must be much higher than a X7R
ceramic capacitor to ensure the same minimum capacitance
over the equivalent operating temperature range.
Adjustable Regulator Design
VOUT1
R1
VOUT2
ADJ1
ADJ2
R2
GND
Micrel, Inc.
R1
R2
MIC2213 Adjustable Regulator Design
The MIC2213 allows the programming of the output voltages
1 and 2 anywhere between 1.25V and 5.5V, the maximum
operating rating of the part. Two resistors are required for each
output. Appropriate resistor values are required to prevent
the low quiescent current performance being compromised.
Resistor values recommended are between 100kΩ and
500kΩ.
The resistor values are calculated by:
R1 = R2 ^VOUT – 1
1.250
where V_OUT is the desired output voltage. Calculate sepa-
rately for each output.
M9999-101705
10
October 2005