MIC29302WU Micrel Inc, MIC29302WU Datasheet - Page 14

• Manufacturer Part Number: MIC29302WU
• Description: IC REG LDO 3.0A ADJ TO-263-5
• Manufacturer: Micrel Inc

Specifications of MIC29302WU

• Regulator Topology: Positive Adjustable
• Voltage - Output: 1.25 ~ 26 V
• Voltage - Input: Up to 26V
• Voltage - Dropout (typical): 0.37V @ 3A
• Number Of Regulators: 1
• Current - Output: 3A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-263-5, D²Pak (5 leads + Tab), TO-263BA
• Primary Input Voltage: 26V
• Output Voltage: 12V
• Dropout Voltage Vdo: 370mV
• No. Of Pins: 5
• Output Current: 3A
• Voltage Regulator Case Style: TO-263
• Operating Temperature Range: -40°C To +125°C
• Svhc: No
• Output Voltage Fixed: 12V
• Rohs Compliant: Yes
• Voltage Regulator Type: Linear
• Topology: LDO
• Regulator Output Type: Adjustable
• Polarity Type: Positive
• Number Of Outputs: Single
• Input Voltage (min): 2.5V
• Input Voltage (max): 26V
• Package Type: TO-263
• Load Regulation: 1%
• Line Regulation: 0.5%
• Output Voltage Accuracy: ±1%
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Dropout Voltage@current (max): 0.175@100mA/0.6@3A
• Dropout Voltage@current (typ): 0.08@100mA/0.25@1.5A
• Pin Count: 5 +Tab
• Mounting: Surface Mount
• Quiescent Current (max): 35mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Lead Free Status / Rohs Status: Compliant
• Other names: 576-3369-5; MIC29302WU

Micrel, Inc.
Applications Information
The MIC29150/29300/29500/29750 are high performance
low-dropout voltage regulators suitable for all moderate to
high-current voltage regulator applications. Their 300mV
to400mV dropout voltage at full load make them especial-
lyvaluable 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-emitter voltage drop and col-
lector-emitter saturation voltage, dropout performance of the
PNP output of these devices is limited merely by the low V
saturation voltage.
A trade-off for the low-dropout voltage is a varying base driver
equirement. But Micrel’s Super ßeta PNP™ process reduces
this drive requirement to merely 1% of the load current.
The MIC29150–29750 family of regulators is fully protected
from damage due to fault conditions. Current limiting ispro-
vided. This limiting is linear; output current under overload
conditions is constant. Thermal shutdown disables the device
when the die temperature exceeds the 125°C maximum safe
operating temperature. Transient protection allows device (and
load) survival even when the input voltage spikes between
–20V and +60V. When the input voltage exceeds about 35V to
40V, the over voltage sensor temporarily disables the regula-
tor. The output structure of these regulatorsallows voltages
in excess of the desired output voltage to be applied without
reverse current flow. MIC29xx1 and MIC29xx2versions offer
a logic level ON/OFF control: when disabled,the devices draw
nearly zero current.
An additional feature of this regulator family is a commonpin-
out: a design’s current requirement may change up ordown
yet use the same board layout, as all of these regulatorshave
identical pinouts.
Thermal Design
Linear regulators are simple to use. The most complicated
design parameters to consider are thermal characteristics.
Thermal design requires the following application-specifi
parameters:
April 2005
Figure 3. Linear regulators require only two capacitorsfor
• Maximum ambient temperature, T
• Output Current, I
• Output Voltage, V
• Input Voltage, V
V
IN
IN
operation.
IN
OUT
GND
OUT
OU T
A
V
O U T
CE
14
First, we calculate the power dissipation of the regulator
fromthese numbers and the device parameters from this
datasheet.
Where the ground current is approximated by 1% of I
Then the heat sink thermal resistance is determined with
thisformula:
Where T
The heat sink may be significantly reduced in applications
where the minimum input voltage is known and is large com-
pared with the dropout voltage. Use a series inputresistor to
drop excessive voltage and distribute the heat between this
resistor and the regulator. The low-dropout properties of Micrel
Super ßeta PNP regulators allow very significant reductions
in regulator power dissipation and the associated heat sink
without compromising performance. When this technique is
employed, a capacitor of at least 0.1µF is needed directly
between the input and regulator ground.
Please refer to Application Note 9 and Application Hint 17
for further details and examples on thermal design and heat
sink specification.
Capacitor Requirements
For stability and minimum output noise, a capacitor on the
regulator output is necessary. The value of this capacitor
is dependent upon the output current; lower currents allow
smaller capacitors. MIC29150—29750 regulators are stable
with the following minimum capacitor values at full load:
Device
MIC29150...............................................10µF
MIC29300...............................................10µF
MIC29500...............................................10µF
MIC29750...............................................22µF
This capacitor need not be an expensive low ESR type:
aluminum electrolytics are adequate. In fact, extremely low
ESR capacitors may contribute to instability. Tantalum capaci-
tors are recommended for systems where fast load transient
response is important.
Where the regulator is powered from a source with a high
AC impedance, a 0.1µF capacitor connected between Input
and GND is recommended. This capacitor should have good
characteristics to above 250kHz.
Minimum Load Current
The MIC29150–29750 regulators are specified between
finite loads. If the output current is too small, leakage cur-
rents dominate and the output voltage rises. The following
minimum load current swamps any expected leakage current
across the operating temperature range:
J MAX
θ
SA
≤ 125°C and θ
P
D
=
=
T
I
J MAX
OUT
P
(
D
1.01 V
−
MIC29150/29300/29500/29750
T
CS
A
IN
−
is between 0 and 2°C/W.
Full Load Capacitor
(
−
θ
V
JC
OUT
+
θ
CS
)
)
M9999-042705
OUT
.