MIC3775-1.8YMM TR Micrel Inc, MIC3775-1.8YMM TR Datasheet - Page 10

• Manufacturer Part Number: MIC3775-1.8YMM TR
• Description: 750mA Low Voltage UCap LDO In Power MSOP-8 Pkg( )
• Manufacturer: Micrel Inc

Specifications of MIC3775-1.8YMM TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.8V
• Voltage - Input: 2.25 ~ 6 V
• Voltage - Dropout (typical): 0.28V @ 750mA
• Number Of Regulators: 1
• Current - Output: 750mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MIC3775-1.8YMMTR; MIC3775-1.8YMMTR

Application Information
The MIC3775 is a high-performance low-dropout voltage
regulator suitable for moderate to high-current voltage
regulator applications. Its 500mV dropout voltage at full
load and overtemperature makes it especially valuable in
battery-powered systems and as high-efficiency noise
filters in post-regulator applications. Unlike older NPN-
pass transistor designs, where the minimum dropout
voltage is limited by the base-to-emitter voltage drop and
collector-to-emitter saturation voltage, dropout perform-
ance of the PNP output of these devices is limited only
by the low V
A trade-off for the low-dropout voltage is a varying base
drive requirement. Micrel’s Superβeta PNP
reduces this drive requirement to only 2% of the load
current.
The MIC3775 regulator is fully protected from damage
due to fault conditions. Linear current limiting is
provided. Output current during overload conditions is
constant. Thermal shutdown disables the device when
the die temperature exceeds the maximum safe
operating temperature. The output structure of these
regulators allows voltages in excess of the desired
output voltage to be applied without reverse current flow.
Output Capacitor
The MIC3775 requires an output capacitor for stable
operation. As a µCap LDO, the MIC3775 can operate
with ceramic output capacitors as long as the amount of
capacitance is 10µF or greater. For values of output
capacitance lower than 10µF, the recommended ESR
range is 200mΩ to 2Ω. The minimum value of output
capacitance recommended for the MIC3775 is 4.7µF.
For 10µF or greater the ESR range recommended is
less than 1Ω. Ultra-low ESR ceramic capacitors are
recommended for output capacitance of 10µF or greater
to help improve transient response and noise reduction
at high frequency. X7R/X5R dielectric-type ceramic
capacitors
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 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
Micrel, Inc.
December 2006
Figure 1. Capacitor Requirements
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saturation voltage.
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10
the same minimum capacitance over the equivalent
operating temperature range.
Input Capacitor
An input capacitor of 1µF or greater is recommended
when the device is more than 4 inches away from the
bulk AC supply capacitance or when the supply is a
battery. Small, surface mount, ceramic chip capacitors
can be used for bypassing. Larger values will help to
improve ripple rejection by bypassing the input to the
regulator, further improving the integrity of the output
voltage.
Error Flag
The MIC3775 features an error flag (FLG), which
monitors the output voltage and signals an error
condition when this voltage drops 5% below its expected
value. The error flag is an open-collector output that
pulls low under fault conditions and may sink up to
10mA. Low output voltage signifies a number of possible
problems, including an overcurrent fault (the device is in
current limit) or low input voltage. The flag output is
inoperative during overtemperature conditions. A pull-up
resistor from FLG to either V
proper operation. For information regarding the minimum
and maximum values of pull-up resistance, refer to the
graph in the “Typical Characteristics” section of the data
sheet.
Enable Input
The MIC3775 features an active-high enable input (EN)
that allows on-off control of the regulator. Current drain
reduces to “zero” when the device is shutdown, with only
microamperes of leakage current. The EN input has
TTL/CMOS compatible thresholds for simple logic
interfacing. EN may be directly tied to V
to the maximum supply voltage.
Transient Response and 3.3V to 2.5V or 2.5V to 1.8V
or 1.65V Conversion
The MIC3775 has excellent transient response to
variations in input voltage and load current. The device
has been designed to respond quickly to load current
variations and input voltage variations. Large output
capacitors are not required to obtain this performance. A
standard 10µF output capacitor, is all that is required.
Larger values help to improve performance even further.
By virtue of its low-dropout voltage, this device does not
saturate into dropout as readily as similar NPN-based
designs. When converting from 3.3V to 2.5V or 2.5V to
1.8V or 1.65V, the NPN-based regulators are already
operating in dropout, with typical dropout requirements
of 1.2V or greater. To convert down to 2.5V or 1.8V
without operating in dropout, NPN-based regulators
require an input voltage of 3.7V at the very least. The
MIC3775 regulator will provide excellent performance
IN
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MIC3775