MIC5191YMM Micrel Inc, MIC5191YMM Datasheet - Page 12

• Manufacturer Part Number: MIC5191YMM
• Description: IC CTRLR LDO/FILTER HS 10MSOP
• Manufacturer: Micrel Inc
• Type: Positive Adjustabler

Specifications of MIC5191YMM

• Number Of Outputs: 1
• Voltage - Output: Adjustable
• Current - Supply: 15mA
• Voltage - Input: 1 ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-1245

Feedback Resistors
The feedback resistors adjust the output to the desired
voltage and can be calculated as follows:
V
output voltage (R1=0) is 0.5V. For output voltages less
than 1V, use the MIC5190.The resistor tolerance adds
error
accumulative for both R1 and R2. For example, our
resistors selected have a ±1% tolerance. This will
contribute to a ±2% additional error on the output
voltage. The feedback resistors must also be small
enough to allow enough current to the feedback node.
Large feedback resistors will contribute to output voltage
error.
For our example application, this will cause an increase
in output voltage of 12mV. For the percentage increase,
By reducing R1 to 100Ω, the error contribution by the
feed-back resistors and feedback current is reduced to
less than 0.1%. This is the reason R1 should not be
greater than 100Ω.
Micrel, Inc.
December 2006
REF
is equal to 1.0V for the MIC5191. The minimum
to
V
V
V
V
V
V
V
ERROR
ERROR
ERROR
ERROR
ERROR
ERROR
OUT
the
Figure 10. Adjustable Output
MIC5191
=
% = 0.8%
= R1 x 1
= 1kΩ x 12µA
= 12mV
%
%
V
output
REF
=
=
IR3716S
12mV
V
1.5V
⎛
⎜
⎝
V
1
ERROR
FB
OUT
+
FB
R2
R1
voltage.
×
100
⎞
⎟
⎠
×
100
R1
R2
These
COUT
GND
V
errors
OUT
are
12
Applying the MIC5191
Linear Regulator
The primary purpose of the MIC5191 is as a linear
regulator, which enables an input supply voltage to drop
down through the resistance of the pass element to a
regulated output voltage.
Active Filter
Another application for the MIC5191 is as an active filter
on the output of a switching regulator. This improves the
power supply in several ways.
First, using the MIC5191 as a filter on the output can
significantly reduce high frequency noise. Switching
power supplies tends to create noise at the switching
frequency in the form of a triangular voltage ripple. High
frequency noise is also created by the high-speed
switching transitions. A lot of time, effort, and money are
thrown into the design of switching regulators to
minimize these effects as much as possible. Figure 9
shows the MIC5191 as a post regulator.
Figure 11 shows the amount of ripple reduction for a 500
KHz switching regulator. The fundamental switching
frequency is reduced from greater than 100mV to less
than 10mV.
Figure 12. 10A Load Transient
Figure 11. Ripple Reduction
M9999-122206
MIC5191