MIC5212 [MICREL]
Dual 500mA LDO Regulator; 双500毫安LDO稳压器
| 型号： | MIC5212 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Dual 500mA LDO Regulator |
| 文件： | 总9页 (文件大小：173K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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.
• 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
Both regulator outputs can supply up to 500mA at the same
time as long as each regulator’s maximum junction tempera-
ture is not exceeded.
Key features include current limiting, overtemperature shut-
down, and protection against reversed battery.
Applications
The MIC5212 is available in a fixed 3.3V/2.5V output voltage
configuration. Othervoltagesareavailable;contactMicrelfor
details.
• 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
Voltage Accuracy Junction Temp. Range*
Package
8-lead SOIC
MIC5212-SJBM
3.3V/2.5V
1.0%
–40°C to +125°C
Other voltages available. Contact Micrel for details.
Typical Application
MIC5212-SJBM
VO1 = 3.3V
VO2 = 2.5V
IN = 5V
4.7µF
INA OUTA
INB
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
SOIC-8 (M)
Pin Description
Pin Number
Pin Name
OUTA
INA
Pin Function
1
Regulator A Output
Regulator A Input
Regulator B Input
Regulator B Output
Ground
2
3
4
INB
OUTB
GND
5, 6, 7, 8
MIC5212
2
April 2003
MIC5212
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Input Voltage (V A or B) ................. –20V to +20V
Supply Input Voltage (V ) ............................... 2.5V to 16V
IN
IN
Power Dissipation (P ) ............................ Internally Limited
Junction Temperature (T ) ....................... –40°C to +125°C
D
J
Storage Temperature Range ................... –60°C to +150°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
Thermal Resistance (θ )......................................... Note 3
JA
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 Typical Max
Units
VO
Output Voltage Accuracy
variation from specified VOUT
–1
–2
1
2
%
%
∆VO/∆T
∆VO/VO
∆VO/VO
Output Voltage
Temperature Coefficient
Note 4
40
ppm/°C
Line Regulation
VIN = VOUT + 1V to 16V
IL = 0.1mA to 500mA, Note 5
0.009
0.05
0.05
0.1
% / V
% / V
Load Regulation
0.7
1.0
%
%
VIN – VO
Dropout Voltage, Note 6
(per regulator)
IL = 150mA
IL = 500mA
175
350
275
350
500
600
mV
mV
mV
mV
IGND
Ground Pin Current, Note 7
(per regulator)
IL = 150mA
IL = 500mA
1.5
12
2.5
3.0
20
mA
mA
mA
mA
25
PSRR
ILIMIT
Ripple Rejection
Current Limit
f = 120Hz, IL = 150mA
75
dB5
mA
VOUT = 0V
750
500
1000
Spectral Noise Density
VOUT = 2.5V, IOUT = 50mA, COUT = 2.2µF
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, T
, the junction-to-ambient thermal resistance, θ , and the ambient temperature, T . The maximum allowable power
J(max)
JA
A
dissipation at any ambient temperature is calculated using: P
= (T
– T ) ÷ θ . Exceeding the maximum allowable power dissipa-
D(max)
J(max)
A
JA
tion will result in excessive die temperature, and the regulator will go into thermal shutdown. The θ of the 8-lead SOIC (M) is 63°C/W
JA
mounted on a PC board (see “Thermal Considerations” section for further details).
Note 4. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 5. 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.
Note 6. 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.
Note 7. 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.
April 2003
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MIC5212
MIC5212
Micrel
Typical Characteristics
MIC5212-3.3 PSRR
MIC5212 PSRR
500mA Load
MIC5212-2.5 PSRR
150mA Load
150mA Load
90
90
90
80
70
60
50
40
30
20 C
80
70
60
50
40
80
70
60
50
40
30
20 C
30 500mA
20 C
OUT = 10µF Tantulum
VIN = 4.3V
OUT = 10µF Tantulum
VIN = 4.3V
OUT = 10µF Tantulum
VIN = 4.3V
10 VOUT = 3.3V
VIN = VOUT + 1V
0
10 VOUT = 3.3V
VIN = VOUT + 1V
0
10 VOUT = 3.3V
VIN = VOUT + 1V
0
10
1k
10
10
10k
100
100k 1M
100
100k 1M
100
1k
100k 1M
10k
1k
10k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
MIC5212-2.5 PSRR
500mA Load
Ground Current
vs. Temperature
S/C Current
vs. Temperature
90
14
800
80
70
60
50
40
30
20
10
0
500mA
700
600
500
400
300
200
100
0
12
10
8
6
300mA
4
COUT = 10µF Tantulum
IN = 4.3V
VOUT = 3.3V
IN = VOUT + 1V
V
2
150mA
100µA
20 40 60 80 100 120
V
0
-40 -20
0
-40 -20
0
20 40 60 80 100 120
10
100
1k
10k 100k 1M
TEMPERATURE (°C)
TEMPERATURE (°C)
FREQUENCY (Hz)
Output Voltage
vs. Temperature
Dropout Voltage
vs. Temperature
Dropout Voltage
vs. Load Current
3.320
3.315
3.310
3.305
3.300
3.295
3.290
3.285
3.280
3.275
500
450
400
350
300
250
200
150
100
50
350
300
250
200
150
100
50
500mA
300mA
150mA
0
0
-40 -20
0
20 40 60 80 100 120
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT CURRENT (mA)
Ground Current
vs. Load
14
12
10
8
6
4
2
0
0
100 200 300 400 500
OUTPUT CURRENT (mA)
MIC5212
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April 2003
MIC5212
Micrel
Output 1 Load Transient Response
Output 2 Load Transient Response
500mA
500mA
10mA
10mA
TIME (1ms/div.)
TIME (1ms/div.)
Output 1 Line Transient Response
Line Transient Response
7V
6V
4.3V
3.5V
TIME (1ms/div.)
TIME (1ms/div.)
Turn-On Response
3.3V, 500mA
2.5V, 200mA
TIME (40µs/div.)
April 2003
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MIC5212
MIC5212
Micrel
Functional Diagram
MIC5212
6
April 2003
MIC5212
Micrel
Lower thermal resistance is achieved by joining the four
ground leads with the die attach paddle to create a single-
piece 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, θ
JC
Output Capacitor
(junction-to-casethermalresistance)andθ (case-to-ambi-
CA
ent thermal resistance). See Figure 1. θ is the resistance
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 out-
put capacitor value may be increased without limit.
JC
from the die to the leads of the package. θ is the resistance
CA
from the leads to the ambient air and it includes θ (case-to-
CS
sink thermal resistance) and θ (sink-to-ambient thermal
SA
resistance).
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 low-
amplitudeoscillationand/orunderdampedtransientresponse.
Most tantalum or aluminum electrolytic capacitors are ad-
equate; 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 recom-
mended for operation below –25°C.
SO-8
θJA
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.
ground plane
heat sink area
θJC
θCA
AMBIENT
printed circuit board
No-Load Stability
Figure 1. Thermal Resistance
TheMIC5212willremainstableandinregulationwithnoload
(other than the internal voltage divider) unlike many other
voltage regulators. This is especially important in CMOS
RAM keep-alive applications.
Using the power SO-8 reduces the θ dramatically and
JC
allows the user to reduce θ . The total thermal resistance,
CA
θ
(junction-to-ambient thermal resistance) is the limiting
JA
Dual-Supply Operation
factor in calculating the maximum power dissipation capabil-
ity of the device. Typically, the power SO-8 has a θ of
20°C/W, this is significantly lower than the standard SO-8
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.
JC
which is typically 75°C/W. θ
is reduced because pins 5
CA
through 8 can now be soldered directly to a ground plane
which significantly reduces the case-to-sink thermal resis-
tance and sink to ambient thermal resistance.
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
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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 opera-
tionofthedevice.Topreventthismaximumjunctiontempera-
ture 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 maxi-
mum 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
900
800
700
600
500
400
300
200
100
0
2
copper is 500mm .
The θ of this package is ideally 63°C/W, but it will vary
JA
depending upon the availability of copper ground plane to
which it is attached.
900
0
0.25 0.50 0.75 1.00 1.25 1.50
POWER DISSIPATION (W)
T
= 125°C
85°C
800
700
600
500
400
300
200
100
0
J
50°C 25°C
Figure 2. Copper Area vs. Power-SO
Power Dissipation (∆T
)
JA
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 maxi-
mum allowable temperature rise must be calculated to deter-
mine operation along which curve.
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 (T )
A
∆T = T
– T
A(max)
J(max)
T
= 125°C
J(max)
T
= maximum ambient operating temperature
A(max)
Forexample, themaximumambienttemperatureis50°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 fol-
lows:
P = (V
– V
– V
) × I
) × I
+ V
+ V
× I
× I
D
IN1
OUT1
OUT2
OUT1
OUT2
IN1
IN2
GND1
+ (V
IN2
GND2
Withacommon5Vinput,a3.3V,300mAoutputonLDO1and
a 2.5V, 150mA output on LDO 2, power dissipation is as
follows:
P = (5V – 3.3V) × 300mA + 5V × 5mA
D
+ (5V – 2.5V) × 150mA + 5V × 1.8mA
P = 0.919W
D
From Figure 2, the minimum amount of copper required to
2
operate this application at a ∆T of 75°C is 500mm .
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
45°
0.0098 (0.249)
0.0040 (0.102)
0.010 (0.25)
0.007 (0.18)
0°–8°
0.197 (5.0)
0.189 (4.8)
0.050 (1.27)
0.016 (0.40)
SEATING
PLANE
0.064 (1.63)
0.045 (1.14)
0.244 (6.20)
0.228 (5.79)
8-Pin SOIC (M)
MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL + 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
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