MIC47100-0.8YML TR Micrel Inc, MIC47100-0.8YML TR Datasheet - Page 10

• Manufacturer Part Number: MIC47100-0.8YML TR
• Description: 1A High Speed, Low Vin LDO In MLF R
• Manufacturer: Micrel Inc

Specifications of MIC47100-0.8YML TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 0.8V
• Voltage - Input: 1 ~ 3.6 V
• Voltage - Dropout (typical): 0.08V @ 1A
• Number Of Regulators: 1
• Current - Output: 1A
• Current - Limit (min): 1.1A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MLF®, QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-3112-2

Micrel, Inc.
Applications Information
The MIC47100 is a high speed, dual supply NMOS LDO
designed to take advantage of point-of-load applications that
use multiple supply rails to generate a low voltage, high
current power supply.
output current while only requiring a 1µF ceramic output
capacitor for stability.
The MIC47100 regulator is fully protected from damage due
to fault conditions, offering linear current limiting and thermal
shutdown.
Bias Supply Voltage
V
to the control portion of the MIC47100. Bypassing on
the bias pin is recommended to improve performance
of the regulator during line and load transients. Small
ceramic capacitors from V
high frequency noise from being injected into the
control circuitry from the bias rail and are good design
practice.
Input Supply Voltage
V
minimum input voltage is 1V, allowing conversion from
low voltage supplies.
Output Capacitor
The MIC47100 requires an output capacitor of 1µF or
greater to maintain stability. The design is optimized
for use with low-ESR ceramic chip capacitors. High
ESR capacitors may cause high frequency oscillation.
The
performance has been optimized for a 1µF ceramic
output capacitor and does not improve significantly
with larger capacitance.
X7R/X5R
recommended
performance.
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 operating temperature ranges. To use a ceramic
chip capacitor with Y5V dielectric, the value must be
much higher than an X7R ceramic capacitor to ensure
the same minimum capacitance over the equivalent
operating temperature range.
Input Capacitor
The MIC47100 is a high-performance, high bandwidth
device. Therefore, it requires a well-bypassed input
supply for optimal performance. A 1µF capacitor is
required from the input to ground to provide stability.
Low-ESR
performance at a minimum of space. Additional high-
September 2008
BIAS
IN
provides the supply to power the LDO. The
, requiring relatively light current, provides power
output
dielectric-type
ceramic
capacitor
because
X7R-type
The MIC47100 can source 1A of
capacitors
can
BIAS
ceramic
of
-to-ground help reduce
capacitors
be
their
provide
increased,
capacitors
temperature
change
optimal
are
but
10
frequency capacitors, such as small-valued NPO
dielectric-type
frequency noise and are good practice in any RF-
based circuit.
Minimum Load Current
The MIC47100, unlike most other regulators, does not
require a minimum load to maintain output voltage
regulation.
Adjustable Regulator Design
The
programming the output voltage anywhere between
0.8V and 2.0V. Two resistors are used. The R1
resistor value between V
not exceed 10kΩ. Larger values can cause instability.
R2 connects between the adjust pin and ground. The
resistor values are calculated by:
Where V
Enable/Shutdown
The MIC47100 comes with a single active-high enable
pin that allows the regulator to be disabled. Forcing
the enable pin low disables the regulator and sends it
into a “zero” off-mode-current state. In this state,
current consumed by the regulator goes nearly to
zero. Forcing the enable pin high enables the output
voltage. The active-high enable pin uses CMOS
technology and the enable pin cannot be left floating;
a floating enable pin may cause an indeterminate
state on the output.
Thermal Considerations
The MIC47100 is designed to provide 1A of
continuous current in a very small package. Maximum
ambient operating temperature can be calculated
based on the output current and the voltage drop
across the part. Given that the input voltage is 1.8V,
the output voltage is 1.2V and the output current is
1A. The actual power dissipation of the regulator
circuit can be determined using the equation:
Because this device is CMOS, the ground current is
insignificant for power dissipation and can be ignored
for this calculation.
To determine the maximum ambient operating
MIC47100
P
P
P
R1
OUT
D
D
D
= (V
= (1.8V – 1.2V) × 1A
= 0.6W
=
is the desired output voltage.
R2
IN
capacitors,
×
– V
⎛
⎜ ⎜
⎝
V
0.7
OUT1
OUT
adjustable
) I
OUT
−
OUT
1
and the adjust pin should
⎞
⎟ ⎟
⎠
help
+ V
BIAS
version
filter
I
GND
M9999-092908-B
out
MIC47100
allows
high-