MICREL MIC5212

MIC5212
Micrel
MIC5212
Dual 500mA LDO Regulator
Final
General Description
Features
The MIC5212 is a dual linear voltage regulator with very-low
dropout voltage (typically 10mV at light loads and 350mV at
500mA), very-low ground current (225µA at 10mA output),
and better than 1% initial accuracy.
Both regulator outputs can supply up to 500mA at the same
time as long as each regulator’s maximum junction temperature is not exceeded.
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Key features include current limiting, overtemperature shutdown, and protection against reversed battery.
The MIC5212 is available in a fixed 3.3V/2.5V output voltage
configuration. Other voltages are available; contact Micrel for
details.
Fused lead frame SOIC-8
Up to 500mA per regulator output
Low quiescent current
Low dropout voltage
Tight load and line regulation
Low temperature coefficient
Current and thermal limiting
Reversed input polarity protection
Applications
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Hard disk drives
CD R/W
Bar code scanners
SMPS post regulator/DC-to-DC modules
High-efficiency linear power supplies
Ordering Information
Part Number
MIC5212-SJBM
Voltage
Accuracy
Junction Temp. Range*
Package
3.3V/2.5V
1.0%
–40°C to +125°C
8-lead SOIC
Other voltages available. Contact Micrel for details.
Typical Application
MIC5212-SJBM
IN = 5V
4.7µF
VO1 = 3.3V
INA OUTA
INB
VO2 = 2.5V
OUTB
GND
4.7µF 4.7µF
3.3V/2.5V Dual LDO
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
April 2003
1
MIC5212
MIC5212
Micrel
Pin Configuration
OUTA 1
8 GND
INA 2
7 GND
INB 3
6 GND
OUTB 4
5 GND
SOIC-8 (M)
Pin Description
Pin Number
Pin Name
1
OUTA
2
INA
Regulator A Input
3
INB
Regulator B Input
4
OUTB
Regulator B Output
5, 6, 7, 8
GND
Ground
MIC5212
Pin Function
Regulator A Output
2
April 2003
MIC5212
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Input Voltage (VIN A or B) ................. –20V to +20V
Power Dissipation (PD) ............................ Internally Limited
Storage Temperature Range ................... –60°C to +150°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
Supply Input Voltage (VIN) ............................... 2.5V to 16V
Junction Temperature (TJ) ....................... –40°C to +125°C
Thermal Resistance (θJA)......................................... Note 3
Electrical Characteristics
Regulator A and B VIN = VOUT + 1V; IL = 100µA; CL = 4.7µF; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.
Symbol
Parameter
Conditions
Min
VO
Output Voltage Accuracy
variation from specified VOUT
–1
–2
∆VO/∆T
Output Voltage
Temperature Coefficient
Note 4
∆VO/VO
Line Regulation
VIN = VOUT + 1V to 16V
0.009
0.05
0.1
%/V
%/V
∆VO/VO
Load Regulation
IL = 0.1mA to 500mA, Note 5
0.05
0.7
1.0
%
%
VIN – VO
Dropout Voltage, Note 6
(per regulator)
IL = 150mA
175
IL = 500mA
350
275
350
500
600
mV
mV
mV
mV
IL = 150mA
1.5
IL = 500mA
12
2.5
3.0
20
25
mA
mA
mA
mA
IGND
Ground Pin Current, Note 7
(per regulator)
Typical
Max
Units
1
2
%
%
40
PSRR
Ripple Rejection
f = 120Hz, IL = 150mA
75
ILIMIT
Current Limit
VOUT = 0V
750
Spectral Noise Density
VOUT = 2.5V, IOUT = 50mA, COUT = 2.2µF
500
ppm/°C
dB5
1000
mA
nV/√Hz
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3.
Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when
operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction
temperature, TJ(max), the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power
dissipation at any ambient temperature is calculated using: PD(max) = (TJ(max) – TA) ÷ θJA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The θJA of the 8-lead SOIC (M) is 63°C/W
mounted on a PC board (see “Thermal Considerations” section for further details).
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load
range from 0.1mA to 500mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V
differential.
Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of
the load current plus the ground pin current.
Note 4.
Note 5.
Note 6.
Note 7.
April 2003
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MIC5212
MIC5212
Micrel
Typical Characteristics
MIC5212 PSRR
500mA Load
90
80
80
70
70
70
60
60
60
1M
0
10
1M
60
50
40
30
COUT = 10µF Tantulum
VIN = 4.3V
VOUT = 3.3V
VIN = VOUT + 1V
0
10
100
1k
10k 100k
FREQUENCY (Hz)
10k 100k
100
1k
FREQUENCY (Hz)
1M
S/C Current
vs. Temperature
10
8
6
300mA
4
2
150mA
100µA
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
3.305
3.300
3.295
3.290
3.285
3.280
DROPOUT VOLTAGE (mV)
3.310
600
500
400
300
200
100
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Dropout Voltage
vs. Temperature
3.320
3.315
700
500mA
12
Output Voltage
vs. Temperature
Dropout Voltage
vs. Load Current
350
500
450
400
350
500mA
300
250
300mA
200
150
150mA
100
50
3.275
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
1M
800
LOAD CURRENT (mA)
GROUND CURRENT (mA)
70
PSRR (dB)
100
1k
10k 100k
FREQUENCY (Hz)
14
80
10
10
COUT = 10µF Tantulum
VIN = 4.3V
VOUT = 3.3V
VIN = VOUT + 1V
Ground Current
vs. Temperature
MIC5212-2.5 PSRR
500mA Load
90
20
20
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
300
250
200
150
100
50
0
500
0
10
30
400
450
1k
100
10k 100k
FREQUENCY (Hz)
10
40
0
50
0
10
20
500mA
COUT = 10µF Tantulum
VIN = 4.3V
VOUT = 3.3V
VIN = VOUT + 1V
DROPOUT VOLTAGE (mV)
10
COUT = 10µF Tantulum
VIN = 4.3V
VOUT = 3.3V
VIN = VOUT + 1V
30
50
300
350
30
40
200
250
40
50
100
150
50
PSRR (dB)
90
80
20
OUTPUT VOLTAGE (V)
MIC5212-2.5 PSRR
150mA Load
90
PSRR (dB)
PSRR (dB)
MIC5212-3.3 PSRR
150mA Load
OUTPUT CURRENT (mA)
Ground Current
vs. Load
GROUND CURRENT (mA)
14
12
10
8
6
4
2
0
0
MIC5212
100 200 300 400 500
OUTPUT CURRENT (mA)
4
April 2003
MIC5212
Micrel
OUTPUT 2 OUTPUT 1
(20mV/div) (20mV/div)
OUTPUT 2 CURRENT
(200mA/div)
1000mA
500mA
10mA
10mA
VIN = 3.3V
VOUT = 2.5V
COUT = 10 F Ceramic
1000mA
500mA
10mA
10mA
TIME (1ms/div.)
TIME (1ms/div.)
Output 1 Line Transient Response
Line Transient Response
VIN = 3.3V
VOUT = 2.5V
COUT = 10 F Ceramic
7V
6V
VIN
(2V/div)
4.3V
3.5V
VOUT 2
(10mV/div)
VOUT 1
VOUT 2
(10mV/div) (10mV/div)
1000mA
VOUT 1
(10mV/div)
VIN
(2V/div)
Output 2 Load Transient Response
VIN = 3.3V
VOUT = 2.5V
COUT = 10 F Ceramic
OUTPUT CURRENT
(500mA/div)
OUTPUT 1 OUTPUT 2
(20mV/div) (20mV/div)
Output 1 Load Transient Response
10mA
TIME (1ms/div.)
TIME (1ms/div.)
VSUPPLY
(2V/div)
2.5V, 200mA
OUTPUT 2
(1V/div)
3.3V, 500mA
OUTPUT 1
(1V/div)
Turn-On Response
TIME (40µs/div.)
April 2003
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MIC5212
MIC5212
Micrel
Functional Diagram
INA
OUTA
Bandgap
Ref.
V
REF
Current Limit
Thermal Shutdown
INB
OUTB
Bandgap
Ref.
V
REF
Current Limit
Thermal Shutdown
GND
MIC5212
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April 2003
MIC5212
Micrel
Lower thermal resistance is achieved by joining the four
ground leads with the die attach paddle to create a singlepiece electrical and thermal conductor. This concept has
been used by MOSFET manufacturers for years, proving
very reliable and cost effective for the user.
Applications Information
Input Capacitor
A 1µF capacitor should be placed from IN to GND if there is
more than 10 inches of wire between the input and the AC
filter capacitor or if a battery is used as the input.
Thermal resistance consists of two main elements, θJC
(junction-to-case thermal resistance) and θCA (case-to-ambient thermal resistance). See Figure 1. θJC is the resistance
from the die to the leads of the package. θCA is the resistance
from the leads to the ambient air and it includes θCS (case-tosink thermal resistance) and θSA (sink-to-ambient thermal
resistance).
Output Capacitor
An output capacitor is required between OUT and GND to
prevent oscillation. 1.0µF minimum is recommended. Larger
values improve the regulator’s transient response. The output capacitor value may be increased without limit.
The output capacitor should have an ESR (Effective Series
Resistance) of about 5Ω or less and a resonant frequency
above 1MHz. Ultra-low-ESR capacitors may cause a lowamplitude oscillation and/or underdamped transient response.
Most tantalum or aluminum electrolytic capacitors are adequate; film types will work, but are more expensive. Since
many aluminum electrolytic capacitors have electrolytes that
freeze at about –30°C, solid tantalum capacitors are recommended for operation below –25°C.
At lower values of output current, less output capacitance is
required for output stability. The capacitor can be reduced to
0.47µF for current below 10mA or 0.33µF for currents below
1mA.
SO-8
θJA
θJC
ground plane
heat sink area
AMBIENT
printed circuit board
No-Load Stability
The MIC5212 will remain stable and in regulation with no load
(other than the internal voltage divider) unlike many other
voltage regulators. This is especially important in CMOS
RAM keep-alive applications.
Figure 1. Thermal Resistance
Using the power SO-8 reduces the θJC dramatically and
allows the user to reduce θCA. The total thermal resistance,
θJA (junction-to-ambient thermal resistance) is the limiting
factor in calculating the maximum power dissipation capability of the device. Typically, the power SO-8 has a θJC of
20°C/W, this is significantly lower than the standard SO-8
which is typically 75°C/W. θCA is reduced because pins 5
through 8 can now be soldered directly to a ground plane
which significantly reduces the case-to-sink thermal resistance and sink to ambient thermal resistance.
Dual-Supply Operation
When used in dual supply systems where the regulator load
is returned to a negative supply, the output voltage must be
diode clamped to ground.
Power SO-8 Thermal Characteristics
One of the secrets of the MIC5212’s performance is its power
SO-8 package featuring half the thermal resistance of a
standard SO-8 package. Lower thermal resistance means
more output current or higher input voltage for a given
package size.
April 2003
θCA
7
MIC5212
MIC5212
Micrel
Quick Method
Low dropout linear regulators from Micrel are rated to a
maximum junction temperature of 125°C. It is important not
to exceed this maximum junction temperature during operation of the device. To prevent this maximum junction temperature from being exceeded, the appropriate ground plane heat
sink must be used.
Determine the power dissipation requirements for the design
along with the maximum ambient temperature at which the
device will be operated. Refer to Figure 3, which shows safe
operating curves for three different ambient temperatures:
25°C, 50°C and 85°C. From these curves, the minimum
amount of copper can be determined by knowing the maximum power dissipation required. If the maximum ambient
temperature is 50°C and the power dissipation is as above,
920mW, the curve in Figure 3 shows that the required area of
copper is 500mm2.
40°C
50°C
55°C
65°C
75°C
85°C
COPPER AREA (mm2)
800
700
100°C
900
600
500
400
The θJA of this package is ideally 63°C/W, but it will vary
depending upon the availability of copper ground plane to
which it is attached.
300
200
100
900
0.25 0.50 0.75 1.00 1.25 1.50
POWER DISSIPATION (W)
COPPER AREA (mm2)
0
0
Figure 2. Copper Area vs. Power-SO
Power Dissipation (∆
(∆TJA)
Figure 2 shows copper area versus power dissipation with
each trace corresponding to a different temperature rise
above ambient.
From these curves, the minimum area of copper necessary
for the part to operate safely can be determined. The maximum allowable temperature rise must be calculated to determine operation along which curve.
800
T = 125°C
J
700
85°C
50°C 25°C
600
500
400
300
200
100
0
0
0.25 0.50 0.75 1.00 1.25 1.50
POWER DISSIPATION (W)
Figure 3. Copper Area vs. Power-SO
Power Dissipation (TA)
∆T = TJ(max) – TA(max)
TJ(max) = 125°C
TA(max) = maximum ambient operating temperature
For example, the maximum ambient temperature is 50°C, the
∆T is determined as follows:
∆T = 125°C – 50°C
∆T = 75°C
Using Figure 2, the minimum amount of required copper can
be determined based on the required power dissipation.
Power dissipation in a linear regulator is calculated as follows:
PD = (VIN1 – VOUT1) × IOUT1 + VIN1 × IGND1
+ (VIN2 – VOUT2) × IOUT2 + VIN2 × IGND2
With a common 5V input, a 3.3V, 300mA output on LDO 1 and
a 2.5V, 150mA output on LDO 2, power dissipation is as
follows:
PD = (5V – 3.3V) × 300mA + 5V × 5mA
+ (5V – 2.5V) × 150mA + 5V × 1.8mA
PD = 0.919W
From Figure 2, the minimum amount of copper required to
operate this application at a ∆T of 75°C is 500mm2.
MIC5212
8
April 2003
MIC5212
Micrel
Package Information
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
0.013 (0.33)
0.050 (1.27)
TYP
0.064 (1.63)
0.045 (1.14)
45°
0.0098 (0.249)
0.0040 (0.102)
0.197 (5.0)
0.189 (4.8)
0°–8°
SEATING
PLANE
0.010 (0.25)
0.007 (0.18)
0.050 (1.27)
0.016 (0.40)
0.244 (6.20)
0.228 (5.79)
8-Pin SOIC (M)
MICREL, INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
The information furnished by Micrel in this datasheet 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2003 Micrel, Incorporated.
April 2003
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MIC5212