MIC5211-LXYM6 TR Micrel Inc, MIC5211-LXYM6 TR Datasheet - Page 8

• Manufacturer Part Number: MIC5211-LXYM6 TR
• Description: MIC5211-3.3/5.0YM6 Dual Cap 50mA LDO ( )
• Manufacturer: Micrel Inc

Specifications of MIC5211-LXYM6 TR

• Regulator Topology: Positive Fixed
• Voltage - Output: 3.3V, 5V
• Voltage - Input: 2.5 ~ 16 V
• Voltage - Dropout (typical): 0.25V @ 50mA
• Number Of Regulators: 2
• Current - Output: 50mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-2749-2; MIC5211-LXYM6 TR; MIC5211-LXYM6TR; MIC5211-LXYM6TR

MIC5211
both regulators are dropping the voltage to 3.0V, then output
current will be limited at higher ambient temperatures.
For example, at 70°C ambient the first regulator can supply
3.0V at 50mA output from a 7.2V supply; however, the sec-
ond regulator will have limitations on output current to avoid
thermal shutdown. The dissipation of the first regulator is:
Since maximum power dissipation for the dual regulator is
250mW at 70°C, the second regulator can only dissipate up
to 34mW without going into thermal shutdown. The amount
of current the second regulator can supply is:
The second regulator can provide up to 8mA output current,
suitable for the keep-alive circuitry often required in hand-
held applications.
Refer to Application Hint 17 for heat sink requirements when
higher power dissipation capability is needed. Refer to Design-
ing with Low Dropout Voltage Regulators for a more thorough
discussion of regulator thermal characteristics.
Dual-Voltage Considerations
For configurations where two different voltages are needed
in the system, the MIC5211 has the option of having two
independent output voltages from the same input. For ex-
ample, a 3.3V rail and a 5.0V rail can be supplied from the
MIC5211 for systems that require both voltages. Important
considerations must be taken to ensure proper functionality
of the part. The input voltage must be high enough for the 5V
section to operate correctly, this will ensure the 3.3V section
proper operation as well.
MIC5211
P
P
P
(7.2V – 3V) I
4.2V • I
I
OUT2(max)
D1
D1
D2(max)
= (7.2V – 3V) 50mA + 7.2V · 0.85mA
= 216mW
OUT2(max)
= 34mW
= 8mA
OUT2(max)
= 34mW
= 34mW
8
Both regulators live off of the same input voltage, therefore
the amount of output current each regulator supplies may
be limited thermally. The maximum power the MIC5211 can
dissipate at room temperature is 455mW, as shown in the
“Thermal Considerations” section. If we assume 6V input
voltage and 50mA of output current for the 3.3V section
of the regulator, then the amount of output current the 5V
section can provide can be calculated based on the power
dissipation.
Based on the power dissipation allowed for the 5V section, the
amount of output current it can source is easily calculated.
(I
tion and in this case can be ignored)
I
Therefore, for this condition, the MIC5211 can supply 50mA
of output current from each section of the regulator.
MAX
GND
exceeds the maximum current rating of the device.
P
P
P
P
P
P
P
P
314.9mW = (6V – 5V) I
314.9mW = (6V – 5V) I
I
typically adds less than 5% to the total power dissipa-
MAX
D
D(3.3V)
D(3.3V)
D(max)
D(max)
D(5V)
D(5V)
D(5V)
= (V
= 314.9mA
= 455mW – 140.1mW
= 314.9mW
= 314.9mW
GND
= 455mW
– P
= (6V – 3.3V) 50mA + 6V · 0.85mA
= 140.1mW
D(3.3V)
– V
OUT
= P
) I
OUT
D(5V)
MAX
MAX
+ V
– 6V · I
GND
· I
GND
GND
Micrel, Inc.
May 2006