MIC35302 DATA SHEET (11/09/2015) DOWNLOAD

MIC35302
3A, Low Voltage µCap LDO Regulator
General Description
Features
The MIC35302 is a 3A low-dropout linear voltage regulator
that provides a low voltage, high current output with a
minimum of external components. It offers high precision,
ultra-low dropout (600mV over temperature), and low
ground current.
The MIC35302 operates from an input of 2.25V to 6.0V. It
is designed to drive digital circuits requiring low voltage at
high currents (i.e., PLDs, DSPs, micro-controllers, etc.),
providing an adjustable output voltage from 1.24V to 5.4V.
Features of the MIC35302 LDO include current limiting
and thermal protection, and reverse current and reverse
battery protection. Also logic (active-HIGH) enable pin is
included. The MIC35302 is available in a 5-pin power
D-Pak package (TO-252) with an operating temperature
range of –40°C to +125°C.
• 3A minimum guaranteed output current
• 600mV maximum dropout voltage over temperature
– Ideal for 3.0V to 2.5V conversion
– Ideal for 2.5V to 1.8V, 1.65V, or 1.5V conversion
• Stable with ceramic or tantalum capacitor
• Wide input voltage range
– VIN: 2.25V to 6.0V
• ±1.0% initial output tolerance
• Excellent line and load regulation specifications
• Logic controlled shutdown
• Thermal shutdown and current limit protection
• Reverse-leakage protection
• –40°C to +125°C junction temperature
• Power D-Pak package (TO-252)
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Applications
•
•
•
•
•
LDO linear regulator for low-voltage digital IC
PC add-in cards
High efficiency linear power supplies
SMPS post regulator
Battery charger
_________________________________________________________________________________________________________________________
Typical Application**
Adjustable Regulator Application
(*See Minimum Load Current Section)
**See Thermal Design Section
Super βeta PNP is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
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MIC35302
Ordering Information
Part Number
Output Current
Voltage
Junction Temp. Range(1)
Package
3A
Adjustable
–40° to +125°C
5-Pin TO-252
MIC35302WD*
Note:
* RoHS compliant with ‘high-melting solder’ exemption.
Pin Configuration
5-Pin TO-252 D-Pak (D)
Pin Description
Pin Number
Pin Name
1
EN
Enable (Input): CMOS compatible input.
Logic high = enable, logic low = shutdown.
2
IN
Input Voltage: Supplies the current to the output power device
3
GND, TAB
Ground: TAB is also connected internally to the IC’s ground on D-PAK.
4
OUT
Regulator Output: The output voltage is set by the resistor divider
connected from OUT to GND (with the divided connection tied to ADJ).
A minimum value capacitor must be used to maintain stability. See
Functional Description Information.
5
ADJ
Adjustable Regulator Feedback Input: Connect to the resistor voltage
divider that is placed from OUT to GND in order to set the output
voltage.
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Pin Function
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MIC35302
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) ..................................... –0.3V to +6.5V
Enable Input Voltage (VEN)........................... –0.3V to +6.5V
Power Dissipation .....................................Internally Limited
Junction Temperature .........................–40°C ≤ TJ ≤ +125°C
Storage Temperature (Ts) ...................–65°C ≤ TJ ≤ +150°C
Lead Temperature (soldering, 5sec.)......................... 260°C
ESD Rating(3) .................................................................. 2kV
Supply voltage (VIN) ................................... +2.25V to +6.0V
Enable Input Voltage (VEN)................................ 0V to +6.0V
Junction Temperature Range .............–40°C ≤ TJ ≤ +125°C
Maximum Power Dissipation..................................... Note 4
Package Thermal Resistance
TO-252 (θJC) ........................................................3°C/W
TO-252 (θJA) ......................................................56°C/W
Electrical Characteristics(5)
TJ = 25°C with VIN = VEN = VOUT + 1V; IOUT = 10mA; bold values indicate –40°C < TJ < +125°C, unless otherwise noted.
Parameter
Condition
Output Voltage Line Regulation
Typ
Max
Units
VIN = VOUT +1.0V to 6.0V
0.02
0.5
%
Output Voltage Load Regulation
IOUT = 10mA to 3A
0.2
1
%
Dropout Voltage, VIN – VOUT
IOUT = 1.5A
250
450
mV
IOUT = 3A
370
600
mV
Ground Pin Current, Note 7
IOUT = 3A
20
50
mA
Ground Pin Current in Shutdown
VIL ≤ 0.5V, VIN = VOUT + 1V
1.0
Current Limit
VOUT = 0
Start-up Time
VEN = VIN, IOUT = 10mA, COUT = 47µF
Note 6
Min
3.5
µA
6
8.5
A
35
150
µs
Enable Input
Enable Input Threshold
Regulator enable
V
2.25
Regulator shutdown
Enable Pin Input Current
VIL ≤ 0.8V (regulator shutdown)
VIH ≥ 2.25V (regulator enabled)
1
15
1.228
1.240
0.8
V
4
µA
75
µA
1.252
V
1.265
V
Adjust Pin
Reference Voltage
1.215
Reference Voltage Temp. Coefficient
Note 8
ppm/°C
20
Adjust Pin Bias Current
40
Adjust Pin Bias Current Temp.
Coefficient
0.1
80
120
nA
nA
nA/°C
Notes:
1.
Exceeding the absolute maximum rating may damage the device.
2.
The device is not guaranteed to function outside its operating rating.
3.
Devices are ESD sensitive. Handling precautions recommended. 200V Machine Model
4.
PD(MAX) = (TJ(MAX) – TA) / θJA, where θJA, depends upon the printed circuit layout. See “Applications Information.”
5.
Specification for packaged product only.
6.
VDO = VIN – VOUT when VOUT decreased to 98% of its nominal output voltage with VIN = VOUT +1V. For output voltages below 1.75V, dropout voltage
specification does not apply due to a minimum input operating voltage of 2.25V.
7.
IGND is the quiescent current. IIN = IGND + IOUT.
8.
Thermal regulation is defined as the change in output voltage at a time t after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 200mA load pulse at VIN = 6V for t = 10ms.
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MIC35302
Typical Characteristics
80
70
50
40
30
IOUT = 3A
COUT = 47µF
10 C = 0
IN
0
0.01 0.1
1
10
100
FREQUENCY (kHz)
20
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80
VIN = 2.5V
VOUT = 1.5V
Power Supply
Rejection Ratio
VIN = 2.5V
VOUT = 1.5V
70
60
PSRR (dB)
PSRR (dB)
60
Power Supply
Rejection Ratio
50
40
30
IOUT = 3A
COUT = 100µF
10 C = 0
IN
0
0.01 0.1
1
10
100
FREQUENCY (kHz)
20
1000
4
1000
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MIC35302
Functional Characteristics
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MIC35302
regulator. The low dropout properties of Micrel Super
ßeta PNP® regulators allow significant reductions in
regulator power dissipation and the associated heat sink
without compromising performance. When this technique
is employed, a capacitor of at least 1.0µF is needed
directly between the input and regulator ground.
Refer to “Application Note 9” for further details and
examples on thermal design and heat sink applications.
With no heat sink in the application, calculate the
junction temperature to determine the maximum power
dissipation that will be allowed before exceeding the
maximum junction temperature of the MIC35302. The
maximum power allowed can be calculated using the
thermal resistance (θJA) of the D-Pak adhering to the
following criteria for the PCB design: 2 oz. copper and
100mm2 copper area for the MIC35302.
As an example, given an expected maximum ambient
temperature (TA) of 75°C with VIN = 2.25V, VOUT = 1.75V,
and IOUT = 2.5A, first calculate the expected PD using
Equation (1);
PD = (2.25V – 1.75V)2.5A + (2.25V)(0.027A) = 1.31W
Next, calcualte the junction temperature for the expected
power dissipation.
Functional Description
The MIC35302 is a high-performance low-dropout
voltage regulator suitable for moderate to high-current
regulator applications. Its 600mV dropout voltage at full
load and over-temperature makes it especially valuable
in battery-powered systems and as high-efficiency noise
filters in post-regulator applications. Unlike older NPNpass transistor designs, there the minimum dropout
voltage is limited by the based-to-emitter voltage drop
and collector-to-emitter saturation voltage, dropout
performance of the PNP output of these devices is
limited only by the low VCE saturation voltage.
A trade-off for the low dropout voltage is a varying base
drive requirement. Micrel’s Super ßeta PNP® process
reduces this drive requirement to only 2% to 5% of the
load current.
The MIC35302 regulator is fully protected from damage
due to fault conditions. Current limiting is provided. This
limiting is linear; output current during overload
conditions is constant. Thermal shutdown disables the
device when the die temperature exceeds the maximum
safe operating temperature. Transient protection allows
device (and load) survival even when the input voltage
spikes above and below nominal. The output structure of
these regulators allows voltages in excess of the desired
output voltage to be applied without reverse current flow.
TJ=(θJA×PD)+TA=(56°C/W×1.31W)+75°C=148.4°C
Now determine the maximum power dissipation allowed
that would not exceed the IC’s maximum junction
temperature (125°C) without the use of a heat sink by
Thermal Design
Linear regulators are simple to use. The most
complicated design parameters to consider are thermal
characteristics. Thermal design requires the following
application-specific parameters:
•
Maximum ambient temperature (TA)
•
Output current (IOUT)
•
Output voltage (VOUT)
•
Input voltage (VIN)
PD(MAX)=(TJ(MAX)–TA)/θJA=(125°C–75°C)/(56°C/W)=0.893W
Output Capacitor
The MIC35302 requires an output capacitor for stable
operation. As a µCap LDO, the MIC35302 can operate
with ceramic output capacitors as long as the amount of
capacitance is 47µF or greater. For values of output
capacitance lower than 47µF, the recommended ESR
range is 200mΩ to 2Ω. The minimum value of output
capacitance recommended for the MIC35302 is 10µF.
For 47µF or greater, the ESR range recommended is
less than 1Ω. Ultra-low ESR ceramic capacitors are
recommended for output capacitance of 47µF or greater
to help improve transient response and noise reduction
at high frequency. X7R/X5R dielectric-type ceramic
capacitors are recommended because of their
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
the same minimum capacitance over the equivalent
operating temperature range.
• Ground current (IGND)
First, calculate the power dissipation of the regulator
from these numbers and the device parameters from this
datasheet.
PD = (VIN – VOUT) IOUT + VIN IGND
(1)
Where the ground current is approximated by using
numbers from the “Electrical Characteristics” or “Typical
Characteristics.” Then, the heat sink thermal resistance
is determined with this formula:
θSA = ((TJ(MAX) – TA)/ PD) – (θJC + θCS)
(2)
Where TJ(MAX) ≤ 125°C and θCS is between 0°C and
2°C/W. The heat sink may be significantly reduced in
applications where the minimum input voltage is known
and is large compared with the dropout voltage. Use a
series input resistor to drop excessive voltage and
distribute the heat between this resistor and the
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MIC35302
Input Capacitor
An input capacitor of 1.0µF or greater is recommended
when the device is more than 4 inches away from the
bulk and supply capacitance, or when the supply is a
battery. Small, surface-mount chip capacitors can be
used for the bypassing. The capacitor should be place
within 1” of the device for optimal performance. Larger
values will help to improve ripple rejection by bypassing
the input to the regulator, further improving the integrity
of the output voltage.
dominate and the output voltage rises. A 10mA minimum
load current is necessary for proper operation.
Enable Input
Transient Response and 3.3V to 2.5V, 2.5V to 1.8V or
1.65V, or 2.5V to 1.5V Conversions
The MIC35302 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 tantalum 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, 2.5V to
1.8V or 1.65V, or 2.5V to 1.5V, the NPN-based
regulators are already operating in dropout, with typical
dropout requirements of 1.2V or greater. To convert
down to 2.5V without operating in dropout, NPN-based
regulators require an input voltage of 3.7V at the very
least. The MIC35302 regulator will provide excellent
performance with an input as low as 3.0V or 2.25V,
respectively. This gives the PNP-based regulators a
distinct advantage over older, NPN-based linear
regulators.
Adjustable Regulator Design
The MIC35302 also features an enable input for on/off
control of the device. Its shutdown state draws “zero”
current (only microamperes of leakage). The enable
input is TTL/CMOS compatible for simple logic interface,
but can be connected to up to VIN. When enabled, it
draws approximately 15µA.
Figure 1. Adjustable Regulator with Resistors
The MIC35302 allows programming the output voltage
anywhere between 1.24V and 5.4V. Two resistors are
used. The resistor values are calculated by:
⎛V
⎞
R1 = R2 × ⎜⎜ OUT − 1⎟⎟
⎝ 1.240 ⎠
Where VOUT is the desired output voltage. Figure 1
shows component definition. Applications with widely
varying load currents may scale the resistors to draw the
minimum load current required for proper operation (see
Minimum Load Current section).
Minimum Load Current
The MIC35302 regulator is specified between finite
loads. If the output current is too small, leakage currents
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MIC35302
Package Information
5-Pin TO-252-5 (D)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2009 Micrel, Incorporated.
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