MIC5238-1.2YD5 TR Micrel Inc, MIC5238-1.2YD5 TR Datasheet - Page 10

• Manufacturer Part Number: MIC5238-1.2YD5 TR
• Description: 150mA Low Vo, Low Iq LDO ( )
• Manufacturer: Micrel Inc

Specifications of MIC5238-1.2YD5 TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.2V
• Voltage - Input: Up to 6V
• Voltage - Dropout (typical): 0.31V @ 150mA
• Number Of Regulators: 1
• Current - Output: 150mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-5, TSOT-5, TSOP-5
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-1834-2; MIC5238-1.2YD5TR; MIC5238-1.2YD5TR

Dual Supply Mode Efficiency
By utilizing a bias supply the conversion efficiency can be
greatly enhanced. This can be realized as the higher bias
supply will only consume a few µA’s while the input supply
will require a few mA’s. This equates to higher efficiency
saving valuable power in the system. As an example,
consider an output voltage of 1V with an input supply of
2.5V at a load current of 150mA. The input ground current
under these conditions is 2mA, while the bias current is
only 20µA. If we calculate the conversion efficiency using
the single supply approach, it is as follows:
Input power = V
current + V
Input power = 2.5V × 150mA + 2.5 × (0.0002+0.002) =
380.5mW
Output power = 1V × 0.15 = 150mW
Efficiency = 150/380.5 × 100 = 39.4%
Micrel, Inc.
November 2008
IN
ground current)
IN
× output current + V
IN
× (V
BIAS
ground
10
Now, using a lower input supply of 1.5V, and powering the
bias voltage only from the 2.5V input, the efficiency is as
follows:
Input power = V
current + V
Input power = 1.5 × 150mA + 1.5 × 0.002 + 2.5 × 0.0002 =
225mW
Output power = 1V × 150mA = 150mW
Efficiency = 150/225 × 100 = 66.6 %
Therefore, by using the dual supply MIC5238 LDO the
efficiency is nearly doubled over the single supply version.
This is a valuable asset in portable power management
applications equating to longer battery life and less heat
being generated in the application.
This in turn will allow a smaller footprint design and an
extended operating life.
BIAS
x V
IN
BIAS
× output current + V
ground current
IN
M9999-111209
× V
MIC5238
IN
ground