Micrel MIC2954 250ma low-dropout regulator Datasheet

MIC2954
Micrel
MIC2954
250mA Low-Dropout Regulator
General Description
Features
The MIC2954 is a “bulletproof” efficient voltage regulator with
very low dropout voltage (typically 40mV at light loads and
375mV at 250mA), and low quiescent current (120µA typical). The quiescent current of the MIC2954 increases only
slightly in dropout, thus prolonging battery life. Key MIC2954
features include protection against reversed battery, foldback current limiting, and automotive load dump protection
(60V positive transient).
The MIC2954-07/08BM is an adjustable version that includes
an error flag output that warns of a low output voltage, which
is often due to failing batteries on the input. This may also be
used as a power-on reset. A logic-compatible shutdown input
is provided which enables the regulator to be switched on and
off. This part may be pin-strapped for 5V output, or programmed from 1.24V to 29V with the use of two external
resistors.
The MIC2954 is available in two voltage tolerances, ±0.5%
maximum and ±1% maximum. Both are guaranteed for
junction temperatures from –40°C to +125°C.
The MIC2954 has a very low output voltage temperature
coefficient and extremely good load and line regulation
(0.04% typical).
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High-accuracy 5V, guaranteed 250mA output
Low quiescent current
Low dropout voltage
Extremely tight load and line regulation
Very low temperature coefficient
Current and thermal limiting
Input can withstand –20V reverse battery and
+60V positive transients
Error flag warns of low output voltage
Logic-controlled electronic shutdown
Output programmable from 1.24V to 29V
(MIC2954-07/08)
Available in TO-220, TO-92, and surface-mount
SOT-223 and SOP-8 packages
Applications
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Battery powered equipment
Cellular telephones
Laptop, notebook, and palmtop computers
PCMCIA VCC and VPP regulation/switching
Bar code scanners
Automotive electronics
SMPS post-regulator/dc-to-dc modules
Voltage reference
High-efficiency linear power supplies
Typical Applications
100k
VIN
MIC2954
IN
VOUT
8
IN
OUT
SHDN ERR
3
GND
SHUTDOWN
ENABLE
2.2µF
FB
1
 R1
VOUT = VREF 1 +

 R2 
4
R1
5
7
GND
5V Fixed Regulator
VOUT
1.2V to 30V
MIC2954
VIN
OUT
VERR
100pF
VREF
10µF
R2
2, 6 = OPEN
Adjustable Regulator
VIN MIC2954-07/-08
+7V 8
1
IN
OUT
3
5
SHDN ERR
SHUTDOWN
ENABLE
FB
GND
4
5V
3.3V
VOUT
5V or 3.3V
100pF
7
220k
1%
300k
1%
VIN
3.3µF
3
180k
1%
OUT
SHDN ERR
1
FB
7
IN
SHUTDOWN
ENABLE
5
VOUT ≈ VIN*
* MINIMUM INPUT-TO-OUTPUT
VOLTAGE RANGES FROM
40mV TO 400mV DEPENDING
UPON LOAD CURRENT
GND
470k
Q1 ON = 3.3V
Q1 OFF = 5.0V
MIC2954-07/-08
8
4
Q1
2N2222
Wide Input-Voltage-Range Current Limiter
5V or 3V Selectable Regulator with Shutdown
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
August 1999
1
MIC2954
MIC2954
Micrel
Ordering Information
Part Number
Accuracy
Junc. Temp. Range
Package
MIC2954-02BT
0.5%
–40°C to +125°C
TO-220
MIC2954-03BT
1.0%
–40°C to +125°C
TO-220
MIC2954-02BS
0.5%
–40°C to +125°C
SOT-223
MIC2954-03BS
1.0%
–40°C to +125°C
SOT-223
MIC2954-02BZ
0.5%
–40°C to +125°C
TO-92
MIC2954-03BZ
1.0%
–40°C to +125°C
TO-92
MIC2954-07BM
0.5%
–40°C to +125°C
SOP-8
MIC2954-08BM
1.0%
–40°C to +125°C
SOP-8
Pin Configuration
GND
MIC2954
TAB
OUT
1
8
IN
SNS
2
7
FB
SHDN
3
6
TAP
GND
4
5
ERR
1
1
TAB
2
3
GND OUT
SOT-223 (S)
SOP-8 (M)
3
2
IN
OUT
IN
3
OUT
2
GND
1
IN
GND
TO-92 (Z)
TO-220 (T)
Pin Description
Pin No.
SOT-223
Pin No.
SOP-8
Pin No.
TO-220
Pin No.
TO-92
Pin Name
Pin Function
1
8
1
1
IN
Supply Input
2, TAB
4
2
2
GND
Ground
3
1
3
3
OUT
Regulator Output
2
SNS
Sense (Input): Output-sense-voltage end of internal resistive
divider. Connect to OUT (VOUT = 5V) for fixed 5V operation;
also see TAP. Not used in adjustable configuration.
3
SHDN
5
ERR
Error Flag (Output): Open collector (active-low) output. Active
state indicates an output (VOUT) undervoltage condition.
(Low = error, floating = normal.)
6
TAP
Divider Tap (Output): Resistive voltage divider tap. With 5V
applied to SNS, VTAP is approximately 1.23V. Connect to
FB for 5V operation. Not used in adjustable configuration.
7
FB
MIC2954
Shutdown (Input): Active-low input enables regulator.
(Low = enable; high = shutdown.)
Feedback (Input): Error amplifier input. Compared to internal
1.23V reference. Connect to external voltage divider for
adjustable operation or internal voltage divider (TAP) for 5V
operation (see SNS, TAP).
2
August 1999
MIC2954
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Input Voltage (VIN) ........................................ –20V to +60V
Feedback Voltage (VFB), Note 14,15 ........... –1.5V to +26V
Shutdown Input Voltage (VSHDN) ................. –0.3V to +30V
Error Output Voltage (VERR) ........................ –0.3V to +30V
Power Dissipation (PD), Note 4 ............... Internally Limited
Storage Temperature (TS) ....................... –65°C to +150°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
ESD, Note 3
Input Voltage (VIN) ....................................... +2.0V to +30V
Junction Temperature (TJ) ....................... –40°C to +125°C
Package Thermal Temperature (θJC, θJA) ................ Note 5
Electrical Characteristics
MIC2954-07/08: VFB = VTAP; VSNS = VOUT; VSHDN ≤ 0.6V. All versions: VIN = 6V; IL = 1mA; CL = 2.2µF; TJ = 25°C,
bold values indicate –40°C ≤ TJ ≤ +125°C; Note 8; unless noted.
Symbol
Parameter
Conditions
VOUT
Output Voltage
∆VOUT/∆T
∆VOUT/VOUT
∆VOUT/VOUT
VIN – VOUT
IGND
Output Voltage
Temperature Coefficient, Note 6
Line Regulation, Note 7
Load Regulation, Note 8
Dropout Voltage, Note 9
Ground Pin Current, Note 10
Min
Typ
Max
Units
MIC2954-02/-07 (±0.5%)
4.975
4.940
5.000
5.025
5.060
V
V
MIC2954-02/-07 (±0.5%), 1mA ≤ IL ≤ 250mA
4.930
5.000
5.070
V
MIC2954-03/-08 (±1%)
4.950
4.900
5.000
5.050
5.100
V
V
MIC2954-03/-08 (±1%), 1mA ≤ IL ≤ 250mA
4.880
5.000
5.120
V
MIC2954-02/-07 (±0.5%)
20
100
ppm/°C
MIC2954-03/-08 (±1%)
20
150
ppm/°C
MIC2954-02/-07 (±0.5%), VIN = 6V to 26V
0.03
0.10
0.20
%/V
%/V
MIC2954-03/-08 (±1%), VIN = 6V to 26V
0.03
0.20
0.40
%/V
%/V
MIC2954-02/-07 (±0.5%), IL = 1 to 250mA,
0.04
0.16
0.20
%/V
%/V
MIC2954-03/-08 (±1%), IL = 1 to 250mA,
0.04
0.20
0.30
%/V
%/V
IL = 1mA
60
100
150
mV
mV
IL = 50mA
220
250
420
mV
mV
IL = 100mA
250
300
450
mV
mV
IL = 250mA
375
450
600
mV
mV
IL = 1mA
140
200
300
µA
µA
IL = 50mA
0.5
1
2
mA
mA
IL = 100mA
1.7
2.5
3.5
mA
mA
IL = 250mA
5
9
12
mA
mA
180
300
µA
750
800
mA
mA
IGND(DO)
Ground Pin Current at Dropout,
Note 10
VIN = 4.5V
ILIMIT
Current Limit, Note 11
VOUT = 0V
August 1999
3
MIC2954
MIC2954
Micrel
Symbol
Parameter
∆VOUT/∆PD
Thermal Regulation, Note 12
en
Output Noise Voltage
(10Hz to 100kHz)
Reference Voltage
Reference Voltage
Conditions
Min
Max
Units
0.05
0.2
%/W
IL = 100mA, CL = 2.2µF
400
µV(rms)
IL = 100mA, CL = 33µF
260
µV(rms)
MIC2954-02/-07 (±0.5%)
1.220
1.200
1.235
1.250
1.260
V
V
MIC2954-03/-08 (±1%)
1.210
1.200
1.235
1.260
1.270
V
V
MIC2954-02/-07 (±0.5%), Note 13
1.190
1.270
V
MIC2954-03/-08 (±1%), Note 13
1.185
1.285
V
40
60
nA
nA
Feedback Pin Bias Current
Reference Voltage
Temperature Coefficient, Note 12
Typ
20
MIC2954-02/-07 (±0.5%)
20
ppm/°C
MIC2954-03/-08 (±1%)
50
ppm/°C
Feedback Pin Bias Current
Temperature Coefficient
0.1
40
nA/°C
Error Comparator
Output Leakage Current
VOH = 30V
0.01
1.00
2.00
µA
µA
Output Low Voltage
VIN = 4.5V, IOL = 400µA
150
250
400
mV
mV
Upper Threshold Voltage
Note 14
60
40
25
mV
mV
Lower Threshold Voltage
Note 14
75
95
140
mV
mV
Hysteresis
Note 14
15
low (on)
1.3
mV
Shutdown Input
Input Logic Voltage
high (off)
Shutdown Pin Input Current
Regular Output Current in
Shutdown
0.7
2.0
V
V
VSHDN = 2.4V
30
50
100
µA
µA
VSHDN = 30V
450
600
750
µA
µA
3
10
20
µA
µA
Note 15
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.
Devices are ESD sensitive. Handling precautions recommended.
Note 4.
PD(max) = (TJ(max) – TA) ÷ θJC. Exceeding TJ(max) will cause thermal shutdown.
Note 5.
Thermal resistance (θJC) of the TO-220 package is 2.5°C/W, and 15°C/W for the SOT-223. Thermal resistance (θJC) of the TO-92 package is
180°C/W with 0.4" leads and 160°C/W with 0.25" leads. Thermal resistance (θJA) of the SOP-8 is 160°C/W mounted on a printed circuit board
(See “Application Information: Thermal Calculation”).
Note 6.
Output voltage temperature coefficient is defined as the worst case voltage change divide by the total temperature range.
Note 7.
Line regulation for the MIC2954 is tested at 125°C for IL = 1mA. For IL = 100µA and TJ = 125°C, line regulation is guaranteed by design to
0.2%. See “Typical Characteristics” for line regulation versus temperature and load current.
Note 8.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Changes in output voltage due to heating effects
are covered by the thermal regulation specification.
Note 9.
Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V
differential. At very low values of programmed output voltage, the minimum input supply voltage of 2 V (2.3V over temperature) must be taken
into account.
Note 10. Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground
pin current.
MIC2954
4
August 1999
MIC2954
Micrel
Note 11. The MIC2954 features fold-back current limiting. The short circuit (VOUT = 0V) current limit is less than the maximum current with normal
output voltage.
Note 12. 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 = 20V (a 4W pulse) for t = 10ms.
Note 13. VREF ≤ VOUT ≤ (VIN – 1V), 2.3V ≤ VIN ≤ 30V, 100 µA < IL ≤ 250 mA, TJ ≤ TJ(max).
Note 14. Comparator thresholds are expressed in terms of a voltage differential at the FB pin below the nominal reference voltage measured at 6V
input. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT /VREF = (R1 + R2)/R2. For
example, at a programmed output voltage of 5V, the error output is guaranteed to go low when the output drops by
95mV × 5V/1.235V = 384mV. Thresholds remain constant as a percent of VOUT as VOUT is varied, with the dropout warning occurring at
typically 5% below nominal, 7.5% guaranteed.
Note 15. VSHDN ≥ 2V, VIN ≤ 30 V,VOUT = 0, with the FB pin connected to TAP.
Note 16. 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.
Note 17. Maximum positive supply voltage of 60V must be of limited duration (<10ms) and duty cycle (<1%). The maximum continuous supply voltage
is 30V.
August 1999
5
MIC2954
MIC2954
Micrel
Typical Characteristics
160
140
120
100
80
60
I L = 1mA
20
1
2
3
4
5
6
7
8
200
I L = 1mA
100
0
-75 -50 -25 0 25 50 75 100 125 150
Ground Pin Current
18
16
14
12
10
8
6
4
2
0
I L = 250 mA
0
1
2
3
4
5
6
7
20
10
30
INPUT OUTPUT VOLTAGE
VOLTAGE
CHANGE (mV)
20
0.01
0
-75 -50 -25 0 25 50 75 100125 150
0.1
I L =10mA
1
10
100
80
I L = 100 mA
70
60
50
I L = 250mA
40
V IN =6V
V OUT =5V
CL=10µF
30
20
10
0.01
1000
0.1
1
10
100
Line Transient Response
0
-400
8V
6V
0.2
0.4
0.6
TIME (mS)
0.8
1
40
-40
8V
6V
1
2
3
TIME (mS)
6
1000
Output Noise Voltage
CL = 2.2 µF
300
CL = 33 µF
200
100
V IN =6V
V OUT =5V
1
10
100
1000
Ripple Rejection
90
80
70
IL=0
60
50
40
30
V IN =6V
V OUT =5V
CL=2.2µF
20
0.01
100
0
0
100
0.1
I L = 100 µA
1
10
100
1000
FREQUENCY (kHz)
CL=33µF
I L=10mA
V OUT =5V
80
10
LOAD CURRENT (mA)
1000
Line Transient Response
CL=2.2µF
I L=10mA
V OUT =5V
1
400
100
FREQUENCY (kHz)
400
0.01
0.1
0
0.1
Ripple Rejection
FREQUENCY (kHz)
0
MIC2954
RIPPLE REJECTION (dB)
50
INPUT OUTPUT VOLTAGE
VOLTAGE
CHANGE (mV)
RIPPLE REJECTION (dB)
I L =1 mA
V IN =6V
V OUT =5V
CL=2.2µF
I L = 100 mA
5
90
80
40
0.1
JUNCTION TEMPERATURE (°C)
90
60
I L = 250mA
15
8
Ripple Rejection
70
1
500
25
INPUT VOLTAGE (V)
100
10
OUTPUT CURRENT (mA)
Ground Pin Current
GROUND PIN CURRENT (mA)
GROUND PIN CURRENT (mA)
20
Ground Pin Current vs Load
TEMPERATURE (°C)
INPUT VOLTAGE (V)
NOISE VOLTAGE (µVrms)
0
300
RIPPLE REJECTION (dB)
0
100
OUTPUT IMPEDANCE ( Ω )
40
Ground Pin Current
400
GROUND PIN CURRENT (mA)
Ground Pin Current
GROUND PIN CURRENT (µA)
GROUND PIN CURRENT (µA)
180
4
5
Output Impedance
V IN =6V
V OUT =5V
CL=10µF
I L=100µA
10
1
0.1
I L=10µA
I L=250mA
0.01
0.01
0.1
1
10
100 1000
FREQUENCY (kHz)
August 1999
MIC2954
Micrel
Load Transient Response
0
CL=2.2µF
-400
-800
250mA
100µA
0
10
20
30
40
100
CL=33µF
0
-100
-200
250mA
100µA
10
OUTPUT
VOLTAGE (V)
CL=33µF
I L=10mA
VIN =14V
VOUT =5V
0
2
0
0
1
2
3
4
5
SHUTDOWN
VOLTAGE (V)
OUTPUT
VOLTAGE (mV)
SHUTDOWN
VOLTAGE (V)
6
2
20
30
40
50
3
I L=250mA
2
1
0
700
CL=2.2µF
4
CL=33µF
2
I L=10mA
VIN =6V
VOUT =5V
0
2
1
2
1
2
4
3
4
5
6
Short Circuit and Maximum
Current vs. Temperature
650
VOUT = VNOMINAL – 0.5V
600
VOUT = 3.3V
550
3 SAMPLES
(HI/AVG/LO)
500
450
400
VOUT = 0V
350
0
0
3
INPUT VOLTAGE (VOLTS)
6
TIME (mS)
5
300
-60 -30
0
30 60 90 120 150
TEMPERATURE (°C)
TIME (mS)
POWER
OUTPUT VOLTAGE
DISSIPATION (W)
CHANGE (V)
I L=100µA
4
60
Enable Transient
CL=2.2µF
4
5
TIME (mS)
10 Enable Transient
Dropout Characteristics
0
0
TIME (mS)
8
6
VIN =6V
VOUT =5V
CURRENT (mA)
400
200
OUTPUT VOLTAGE (V)
VIN =6V
VOUT =5V
OUTPUT VOLTAGE
CHANGE (mV)
Load Transient Response
LOAD
CURRENT
LOAD
CURRENT
OUTPUT VOLTAGE
CHANGE (mV)
800
Thermal Regulation
15
10
5
0
-5
4
2
0
0
10
20
30
40
TIME (mS)
August 1999
7
MIC2954
MIC2954
Micrel
Block Diagrams
Unregulated
DC Supply
IN
OUT
5V/250mA
Output
Error
Amp.
182k
62k
2.2µF
1.23V
REF.
GND
MIC2954-02/-03
MIC2954-02 and MIC2954-03
Unregulated
DC Supply
FB
IN
OUT
SNS
Error
Amp.
182k
SHDN
TTL/CMOS
Control Logic
Input
60k
Error Detection
Comparator
60mV
5V/250mA
Output
1.23V
REF.
TAP
ERR
330k
TTL/CMOS
Compatible
Error Output
GND
MIC2954-07/-08
MIC2954-07 and MIC2954-08
MIC2954
8
August 1999
MIC2954
Micrel
Programming the Output Voltage
(MIC2954-07/-08)
The MIC2954-07/-08 may be pin-strapped for 5V using its
internal voltage divider by tying pin 1 (OUT) to pin 2 (SNS) and
pin 7 (FB) to pin 6 (TAP). Alternatively, it may be programmed
for any output voltage between its 1.235V reference and its
30V maximum rating. An external pair of resistors is required,
as shown in Figure 3.
The complete equation for the output voltage is
Applications Information
External Capacitors
A 2.2µF (or greater) capacitor is required between the MIC2954
output and ground to prevent oscillations due to instability.
Most types of tantalum or aluminum electrolytics will be
adequate; film types will work, but are costly and therefore not
recommended. Many aluminum electrolytics have electrolytes that freeze at about –30°C, so solid tantalums are
recommended for operation below –25°C. The important
parameters of the capacitor are an effective series resistance
of about 5Ω or less and a resonant frequency above 500kHz.
The value of this capacitor may be increased without limit.
At lower values of output current, less output capacitance is
required for output stability. The capacitor can be reduced to
0.5µF for current below 10mA or 0.15µF for currents below
1mA. Adjusting the MIC2954-07/-08 to voltages below 5V
runs the error amplifier at lower gains so that more output
capacitance is needed. For the worst-case situation of a
250mA load at 1.23V output (output shorted to feedback) a
5µF (or greater) capacitor should be used.
The MIC2954 will remain in regulation with a minimum load
of 1mA. When setting the output voltage of the MIC2954-07/
-08 version with external resistors, the current through these
resistors may be included as a portion of the minimum load.
A 0.1µF capacitor should be placed from the MIC2954 input
to ground 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.
Error Detection Comparator Output
(MIC2954-07/-08)
A logic-low output will be produced by the comparator whenever the MIC2954-07/-08 output falls out of regulation by
more than approximately 5%. This figure is the comparator’s
built-in offset of about 60mV divided by the 1.235V reference
voltage. (Refer to the block diagram on page 1). This trip level
remains “5% below normal” regardless of the programmed
output voltage of the MIC2954-07/-08. For example, the error
flag trip level is typically 4.75V for a 5V output or 11.4V for a
12V output. The out of regulation condition may be due either
to low input voltage, current limiting, or thermal limiting.
Figure 1 is a timing diagram depicting the ERR signal and the
regulated output voltage as the MIC2954-07/-08 input is
ramped up and down. The ERR signal becomes valid (low) at
about 1.3V input. It goes high at about 5V input (the input
voltage at which VOUT = 4.75). Since the MIC2954-07/-08’s
dropout voltage is load-dependent (see curve in “Typical
Characteristics”), the input voltage trip point (about 5V) will
vary with the load current. The output voltage trip point
(approximately 4.75V) does not vary with load.
The error comparator has an open-collector output which
requires an external pull-up resistor. Depending on system
requirements, this resistor may be returned to the 5V output
or some other supply voltage. In determining a value for this
resistor, note that while the output is rated to sink 400µA, this
sink current adds to battery drain in a low battery condition.
Suggested values range from 100k to 1MΩ. The resistor is
not required if this output is unused.
August 1999
 R1
VOUT = VREF 1 +
 + I R1
 R2  FB
where:
VREF = nominal 1.235V reference voltage
IFB = nominal FB pin bias current (–20nA)
The minimum recommended load current of 1µA forces an
upper limit of 1.2MΩ on the value of R2, if the regulator must
work with no load (a condition often found in CMOS in
standby), IFB will produce a 2% typical error in VOUT which
may be eliminated at room temperature by trimming R1. For
better accuracy, choosing R2 = 100k reduces this error to
0.17% while increasing the resistor program current to 12µA.
Since the MIC2954-07/-08 typically draws 60µA at no load
with pin 2 (SNS) open-circuited, this is a negligible addition.
Reducing Output Noise
In reference applications it may be advantageous to reduce
the ac noise present at the output. One method is to reduce
the regulator bandwidth by increasing the size of the output
capacitor. This is relatively inefficient, as increasing the
capacitor from 1µF to 220µF only decreases the noise from
430µV to 160µVRMS for a 100kHz bandwidth at 5V output.
Noise can be reduced fourfold by a bypass capacitor across
R1, since it reduces the high frequency gain from 4 to unity.
Pick:
CBYPASS ≅
1
2πR1× 200Hz
4.75V
Output
Voltage
ERR
*
Not
Valid
*
Not
Valid
Input
Voltage
5V
1.3V
*See Application Information
Figure 1. Error Output Timing
9
MIC2954
MIC2954
Micrel
Multilayer boards having a ground plane, wide traces near the
pads, and large supply bus lines provide better thermal
conductivity.
Our calculations will use the “worst case” value of 160°C/W,
which assumes no ground plane, minimum trace widths, and
a FR4 material board.
Pad Layout (minimum recommended geometry)
or about 0.01µF. When doing this, the output capacitor must
be increased to 3.3µF to maintain stability. These changes
reduce the output noise from 430µV to 100µV rms for a
100kHz bandwidth at 5V output. With the bypass capacitor
added, noise no longer scales with output voltage so that
improvements are more dramatic at higher output voltages.
Automotive Applications
The MIC2954 is ideally suited for automotive applications for
a variety of reasons. It will operate over a wide range of input
voltages with very low dropout voltages (40mV at light loads),
and very low quiescent currents (75µA typical). These
features are necessary for use in battery powered systems,
such as automobiles. It is a “bulletproof” device with the ability
to survive both reverse battery (negative transients up to 20V
below ground), and load dump (positive transients up to 60V)
conditions. A wide operating temperature range with low
temperature coefficients is yet another reason to use these
versatile regulators in automotive designs.
50 mil
245 mil
150 mil
Thermal Calculations
Layout Considerations
The MIC2954-07BM/-08BM (8-pin surface-mount package)
has the following thermal characteristics when mounted on a
single layer copper-clad printed circuit board.
30 mil
Nominal Power Dissipation and Die Temperature
The MIC2954-07BM/-08BM at a 55°C ambient temperature
will operate reliably at up to 440mW power dissipation when
mounted in the “worst case” manner described above. This
power level is equivalent to a die temperature of 125°C, the
recommended maximum temperature for nonmilitary grade
silicon integrated circuits.
θJA
PC Board Dielectric Material
FR4
160°C/W
Ceramic
120°C/W
50 mil
Schematic Diagram
FEEDBACK
IN
R18
20kΩ
Q15A
Q15B
Q24
Q26
Q25
OUT
Q9
Q3
R11
18
kΩ
Q4
Q7
Q6
R11
20.6
kΩ
Q1
10
R2
50 kΩ
Q16
Q17
R27
182 kΩ
R17
12 kΩ
Q14
5V TAP
R28
60 kΩ
Q2
Q20
R1
20 kΩ
Q42
SENSE
Q8
Q5
C1
20
pF
R5
180
kΩ
Q40
R6
140
kΩ
Q13
Q22
R10
150
kΩ
R8
31.4 kΩ
Q21
R12
110
kΩ
Q12
Q41
Q23
C2
40 pF
R9
27.8 kΩ
R13
100
kΩ
R15
100 kΩ
R14
350
kΩ
R16
30 kΩ
Q11
R17
10 Ω
Q29
R30
30
kΩ
Q18
Q19
Q28
R3
50 kΩ
R4
13 kΩ
R21 8 Ω
50 kΩ
Q30 Q31
Q37
10 kΩ
R22
150 kΩ
Q36
R23 60 kΩ
ERROR
Q38
Q34
R26
60 kΩ
DENOTES CONNECTION ON
MIC2954-02Bx/-03Bx ONLY
R25
2.8 kΩ
GND
Q39
MIC2954
SHDN
R24
50 kΩ
10
August 1999
MIC2954
Micrel
Package Information
0.151 D ±0.005
(3.84 D ±0.13)
0.410 ±0.010
(10.41 ±0.25)
0.108 ±0.005
(2.74 ±0.13)
0.176 ±0.005
(4.47 ±0.13)
0.590 ±0.005
(14.99 ±0.13)
0.818 ±0.005
(20.78 ±0.13)
0.050 ±0.005
(1.27 ±0.13)
7°
0.356 ±0.005
(9.04 ±0.13)
7°
3°
1.140 ±0.010
(28.96 ±0.25)
0.050 ±0.003
(1.27 ±.08)
0.030 ±0.003
(0.76 ±0.08)
0.100 ±0.020
(2.54 ±0.51)
0.018 ±0.008
(0.46 ±0.020)
0.100 ±0.005
(2.54 ±0.13)
DIMENSIONS: INCH
(MM)
TO-220 (T)
0.090 (2.286) Radius, typ.
2
3
1
0.145 (3.683)
0.135 (3.429)
0.055 (1.397)
0.045 (1.143)
10° typ.
BOTTOM VIEW
0.085 (2.159) Diam.
0.185 (4.699)
0.175 (4.445)
5° typ.
0.185 (4.699)
0.175 (4.445)
0.090 (2.286) typ.
5° typ.
Seating Plane
0.025 (0.635) Max
Uncontrolled
Lead Diameter
0.500 (12.70) Min.
0.016 (0.406)
0.014 (0.356)
0.0155 (0.3937)
0.0145 (0.3683)
0.055 (1.397)
0.045 (1.143)
0.105 (2.667)
0.095 (2.413)
TO-92 (Z)
August 1999
11
MIC2954
MIC2954
Micrel
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°–8°
0.197 (5.0)
0.189 (4.8)
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)
SOP-8 (M)
3.15 (0.124)
2.90 (0.114)
CL
3.71 (0.146) 7.49 (0.295)
3.30 (0.130) 6.71 (0.264)
CL
2.41 (0.095)
2.21 (0.087)
1.04 (0.041)
0.85 (0.033)
4.7 (0.185)
4.5 (0.177)
0.10 (0.004)
0.02 (0.0008)
DIMENSIONS:
MM (INCH)
6.70 (0.264)
6.30 (0.248)
1.70 (0.067)
16°
1.52 (0.060)
10°
10°
MAX
0.038 (0.015)
0.25 (0.010)
0.84 (0.033)
0.64 (0.025)
0.91 (0.036) MIN
SOT-223 (S)
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
USA
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
© 1999 Micrel Incorporated
MIC2954
12
August 1999