Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
100mA Low Dropout Voltage Regulator LM2931
Pin Connection
Ordering Information
8SOIC (M)
Package Tolerance
SOT-89 LM2931R-XX
TO-92 LM2931Z-XX
8-SOIC LM2931M-XX
“XX” Voltag e Selection Guide
Vout XX Code
3.3V 33
5.0V 50
8.0V 80
8.5V 85
9.0V 90
10.0V 10
12.0V 12
15.0V 15
Adjustable Left Blank
Description
The Bay Linear LM2931 are low power voltage regulators
designed for a wide range of applications. They are an
excellent choice for use in Battery Powered applications. The
LM2931 feature low quiescent current (100 µA Typ.) and low
dropout of only 60mV at light loads and 300mV (typ.) at
100mA. The LM2931 has tight initial tolerance of 0.5% typ.,
extremely good load and line regulation of 0.05% typ. and very
low output temperature coefficient .
The Bay Linear LM2931 is available as a fixed voltage
regulator and as an adjustable regulator in TO-92 and 8SOIC
packages. The Bay Linear LM2931 in an 8SOIC package has
an adjustable output voltage from 3V to 24V, programmed
with a pair of external resistor. The logic compatible shutdown
enables the regulator to be switched ON and OFF.
Features
• Guaranteed 100mA Output
• Fixed Versions 3.3V, 50.V, 8.0
• Very Low Quiescent Current
• Low Dropout Voltage
• Extremely Tight Load and Line
Regulation
• Very Low Temperature Coefficient
• Current and Thermal Limiting
• Reverse Battery Protection of –20V
• Transient protection of 60V
• Output programmable from 3V to 24V
Applications
• Battery Powered Systems
• Portable instrumentation
• Notebooks Computers
• Potable Consumer Equipment
• Automotive electronics
• SMPS Post-Regulator
Bay Linear
Bay LinearBay Linear
Bay Linear
Linea r Exc e lle nc e
1
2
4
3
5
6
7
8
Output Input
GND
GND
GND
GND
Feedback Shutdown
SOT-89
Front Vie w
INPUT GND OUTPUT
BAY
LM2931
OUTPUT
GROUND
INPUT
13
2
TO-92
Bo ttom View
SOT-89
Front Vie w
INPUT GND OUTPUT
BAY
LM2931
SOT-89
Front Vie w
INPUT GND OUTPUT
BAY
LM2931
OUTPUT
GROUND
INPUT
13
2
TO-92
Bo ttom View
OUTPUT
GROUND
INPUT
13
2
TO-92
Bo ttom View
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM2931
Absolute Maximum Rating
Parameter
Power Dissipation Internally Limited
Lead Temperature ( Soldering 5 seconds ) 260 °C
Storage Temperature Range -65 °C to +150 °C
Operatin g Junction Temperatu r e -55 °C to +150 °C
Input Supply Voltage -20 to +35V
Electrical Characteristics
TJ = 25°C , IO = 100µA, V IN = 14V ( for 2931-15 VIN = 16V), CO = 100µF; unless otherwise specified)
Parameter Conditions MIN TYP MAX UNIT
Output Voltage
(Fixed Version) -25 °C ≤ Tj ≤ 85 °C
Full Operat ing Temperatur e 0.985 [ Vo ]
0.98 [ Vo ]
Vo 1.015 [ Vo ]
1.02 [ Vo ]
V
Output V oltage (Fixed V ersion) 100µA ≤ IL ≤ 100mA, Tj ≤ T jmax 0.975 [Vo ] Vo 1.025 [ Vo ] V
Input Supply Voltage 26 V
Output Voltage Temperature
Coefficient (Note 1) 50 150 ppm / ° C
Line Regulation (Note 2) 13V ≤ VIN ≤ 26V (Note 3 ) 0.1 0.4 %
Load Regulation (Note 2) 100µA ≤ IL ≤ 100mA 0.1 0.3 %
Dropout Voltage (Note 4) IL = 100µA
IL = 100mA 60
300 200
600 mV
Ground Current (Note 5) IL = 100µA
IL = 10mA
IL = 100mA
100
0.9
8
150
1.5
12
µA
mA
mA
Dropout Ground Current VIN = (VOUT – 0.5V ), IL = 100µA 110 170
µA
Current Limit VOUT = 0 160 200 mA
Thermal Regulation (Note 6) 0.05 0.2 % / W
Output Noise,
10Hz to 100KHz
IL = 10mA
CL = 2.2µF
CL = 3.3µF
CL = 33µF
500
350
120
µVrms
Ripple Rejection Ratio IO = 10mA, f = 120Hz, C0 = 100µF
VIN = VO + 3V+2Vpp 60 dB
8 pin Versions only (LP2951)
Reference Vo ltage
Over Temperatur e (Note 7) 1.21
1.185 1.235 1.26
1.285 V
Feedback Pin Bias Current 20 40 ηA
Reference Voltage Temperature
Coefficient (Note 1) 50 ppm/°C
Feedback Pin Bias Current
Temperature Coefficient 0.1
ηA/°C
Shutdown Input
Inpu t Logic Voltage Low (Regulator ON)
High (Regulator OFF)
2 1.3 0.7 V
Shutdown Pin Input Current VS = 2.4V
VS = 26V 30
450 50
600 µA
Regulator Output Current
in Shutdown (Note 8)
5.0V ≤ VOUT ≤ 15.0V
3.3V ≤ VOUT ≤ 5.0V
2.0V ≤ VOUT ≤ 3.3V
10
20
30
µA
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM2931
Note 1: Output or referenc e voltage t emperature coeffici ents defined as the worst ca se voltage chan ge divid ed by the total temperatu r e range.
Note 2: Unless otherwise specif ied all lim its guaranteed for TJ = 25°C, VIN = VO +1V, IL = 100µA and CL = 1µF. Additional conditions for the 8-
pin versions are feedback tied to –XX Voltage tap and output tied to output Sense pin ( VOUT = XX V) and VSHUTDOWN ≤ 0.8 V
Note 2: Regulation is measured at constant jun ction temperat ure , usi ng pulse test ing with a low duty cycle. Changes in ou tput volta ge due to
heating effects are covered under specification for th ermal regulation.
Note 3: Line regulation for is tested at 150°C for IL = 1mA. For IL = 100µA and TJ = 125°C, line regu lation is guaranteed by design to 0.2%. for
B2931-15 16V ≤ VIN ≤ 26V.
Note 4: Dropout voltage is defined as the inpu t to output differential at which the output voltage drops 2% below its nominal value measured at
1V diff e r ential.
Note 5: Ground pin Current is the regulator quiescent current. The total current drawn from the source is the sum of the ground pin curre nt an d
output load cu rrent.
Note 6: Thermal regulation is the change in output volta ge at a time T after a change in power dissipation , excludi ng load or li ne regulation
effects. Specifications are for a 50 mA load pulse (1.25W) for T = 10ms.
Note 7: VREF ≤ VOUT ≤ (VIN –1V), 2.3V ≤ VIN ≤ 26V , 100µA ≤ IL ≤100mA , TJ ≤ TJMAX
Note 8: VSHUTDOWN ≥ 2V, VIN ≤ 26V, VOUT = 0
Application H ints
The LM2931 requires an output capacitor for device
stability. The value required varies greatly
depending upon the application circuit and other
factors. The high frequency characteristics of
electrolytic capacitors depend greatly on the type and
also on the manufacturer. Sometimes only bench
testing is the only means to determine the proper
capacitor type and value. The high quality 100 µF
aluminum electrolytic covers all general application
circuits, this stabilit y can be o btained with a ta ntal u m
electrolytic value of 47 µF.
Another critical point of electrolytic characteristics is
its performance over temperature. The LM2931 is
designed to operate starting at -40°C which may not
be true in the case of electrolytic. Higher
temperatures generally no problem. The electrolytic.
type in aluminum will freeze around -30°C. This
could cause an oscillation at output of regulator. At a
lower temperature requirement by many applications
the capacitor should maintai n its performance. So as
a result, for an application which regulator junction
temperature does not exceed 25°C, the output
capacitor can be reduced by the
factor of two over the value needed for the entire
temperature range.
Other points with linear regulators are that the twitch
higher output current stability decreases. In most
applications the LM2931 is operating at few
milliamps. In these applications the output capacitance
can be further reduced. For example, when the
regulator is running at 10mA output current the output
capacitance value is half compared to the same
regulator that is running at 100 mA.
With the LM2931 adjustable regulator, the minimum
value of output capacitance is a function of the output
voltage. The value decreases with higher output
voltages, since the internal loop gain is reduced.
The worst case occurs at the lower temperature and
maximum operating currents, the entire circuit and the
electrolytic, should be cooled down to the minimum
temperature. The minimum of 0.6 volts required at
the input of regulator above the output to keep the
power dissipation and die heating to its minimum.
After the value for the capacitor has been determined
for actual use, the value should be doubled.
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM2931
TYPICAL CHARACTERISTICS
INPUT OUTPUT DIFFERENTIAL (V)
0.6
0.5
0.2
0
JUNCTION TEMPERATURE (ºC)
QUIESCENT CURRENT (mA)
25
3
2
0-40 0 80 120
JUNCTION TEMPERATURE (ºC)
0.4
0.3
0.1
040 80 120
DROPOUT VOLTAGE
QUIESCENT CURRENT
6.0
3.0
2.0
1.0 2.0 3.0 4.0 5.0 6.0
INPUT VOLTAGE (V)
LOW VOLTAGE BEHAVIOR
OUTPUT VOLTAGE (V)
1.0
0.8
0.6
0.5
0 5 10 15 20 25 30
AMBIENT TEMPERATURE (ºC)
MAXIMUM POWER DISSIPATION (SO-
8)
POWER DISSIPATION (W)
0.9
0.7
0.4
10
1
0.1
0 30 60 90 120 150
FREQUENCY (Hz)
MAXIMUM POWER DISSIPATION
OUTPUT IMPEDANCE (
Ω)
Ω)Ω)
Ω)
0.01
INPUT OUTPUT DIFFERENTIAL (V)
0.4
0.2
OUTPUT CURRENT (mA)
QUIESCENT CURRENT (mA)
00
OUTPUT CURRENT (mA)
0.3
0.1
0
DROPOUT VOLTAGE
QUIESCENT CURRENT
22
20
6
0
01020 40 70 80 100
AMBIENT TEMPERATURE (ºC)
MAXIMUM POWER DISSIPATION (TO-220)
POWER DISSIPATION (W)
REFERENCE VOLTAGE (V)
1.10 18 21
OUTPUT VOLTAGE (V)
REFERENCE VOLTAGE
OUTPUT CURRENT (mA)
800
500
0
INPUT VOLTAGE (V)
200
100
10 20
PEAK OUTPUT CURRENT
1.0
020405060
AMBIENT TEMPERATURE (ºC)
MAXIMUM POWER DISSIPATION (TO-92)
POWER DISSIPATION (W)
30 60 90
5
10
15
20
25
30
0 50 100
1.12
1.18
1.22
1.26
1.30
912
300
400
0.9
0.8
0.7
0.6
0.5
0.4
OPERATION DURING LOAD DUMP
TIME (ms)
OUTPUT
VOLTAGE (V)
400
200
100-100
30
10
0
6
4
-2
10
15
20
15
30
18
2
0
0 300
1
~
~~
~
40
I
O
= 0mA
I
O
= 50mA
V
IN
= 14V
24630
1.14
1.16
1.24
1.20
1.28
LM2931CT ADJUSTABLE
I
O
= 100mA
I
O
= 50mA
I
O
= 10mA
0.5
0.6
0
T
J
= 25ºC
T
J
= 85ºC
T
J
= -40ºC
4.0
5.0
LM2931 5.0
IO = 100 mA
INFINITE HEAT SINK
10 ºC/W HEAT SINK
NO HEAT SINK
14
16
12
10
8
4
2
30 50 60 90
0.1
0.3
0.2
0
10 30 70 80 90
0.125" LEAD LENGTH
FROM PC BOARD
0.4" LENGTH
FROMPC BOARD
LM2931-
5.0
I
O
= 10mA
0.3
0.2
0.1
0
~
~
20
40
50
60
70
500
OUTPUT
VOLTAGE (V)
~
~
C
O
= 100µF
R
L
= 500W
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM2931
TYPICAL APPLICATIONS
LM2931 ADJUSTABLE OUTPUT
LM2931
ADJ.
LM2931 ADJUSTABLE OUTPUT
LM2931
ADJ.
LM2931
LM2931 Fixe d Output
LM2931
LM2931 Fixe d Output
SCHEMATIC DIAGRAM
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM2931
PACKAGE DRAWING TO-92(Z)
1
2
3
0.055 (1.397)
0.045 (1.143)
0.145 (3.683)
0.135 (3.429)
10° typ.
BOTTOM VIEW
0.185 (4.699)
0.045 (1.143)
0.185 (4.699)
0.175 (4.445)
0.085 (2.159) Diameter
0.090 (2.286) typ.
Seating Plane
0.016 (0.406)
0.014 (0.356)
0.055 (1.397)
0.045 (1.143)
0.105 (2.667)
0.095 (2.413)
0.500 (12.70) Min.
0.025 (0.635) Max
Uncontrolled
Lead Diameter
5° typ.
5° typ.
0.090 (2.286) Radius typ.
0.0155 (0.3937)
0.0145 (0.3683)
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM2931
PACKAGE DRAWING
SO-8(M)
Pin 1
1.27 (0.50)
BSC
3.8 (0.150)
4.0 (0.158) 4.6 (0.181)
5.2 (0.205) 5.8 (0.228)
6.2 (0.244)
4.8 (0.188)
5.0 (0.197)
0.49 (0.019)
0.56 (0.022)
0.35 (0.014)
0.45 (0.018)
0.10 (0.004)
0.20 (0.008) 0.19 (0.007)
0.22 (0.009)
1.35 (0.053)
1.75 (0.069)
0.61 (0.024)
0.78 (0.031)
3
°
-6
°
0.64 (0.025)
0.77 (0.030)
45
°
7
°
(4 PLCS)
7
°
(4 PLCS)
0.37 (0.015)
BSC
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM2931
PACKAGE DRAWING
SOT-89®
Advance Information- These data sheets contain descriptions of products that are in development. The specifications are based on the engineering calculations,
computer simulations and/ or initial prototype evaluation.
Preliminary Information- These data sheets contain minimum and maximum specifications that are based on the initial device characterizations. These limits are
subject to change upon the completion of the full characterization over the specified temperature and supply voltage ranges.
The applicati on circuit examples ar e only to explain the representati ve applicatio ns of the devices and ar e not intended to guarantee any c ircuit
desi gn or permit any industrial prop erty right to other rights to execute. Bay Linear takes no responsibility for any prob lems related to any
industrial property right resulting from the use of th e conten ts shown in the data book. Typical parameters can and do vary in different
applications. Customer’s technical experts must validate all operating parameters including “ Typical” for each customer application.
LIFE SUPPORT AND NUCLEAR POLICY
Bay Linear products are not authorized for and should not be used within life support systems which are intended for surgical
implants into the body to support or sustain life, in aircraft, space eq uipment, submarine, or nuclear facility applications without
the specific written consent of Bay Linear President.
A
123
P
K
F
G
D
B
STYLE 1
PIN 1. BASE
2. COLLECTOR
3. EMITTER
STYLE 3
PIN 1. GATE
2. ANODE
3. CATHODE
STYLE 2
PIN 1. ANODE
2. CATHODE
3. NO CONNECTION
PIN 1. DRAIN
2. GATE
3. SOURCE
STYLE 4
MILLIMETERS INCHES
DIM MIN MAX MIN MAX
A 4.40 4.60 0.174 0.181
B 2.29 2.60 0.091 0.102
C 140 160 0.056 0.062
D 0.36 0.48 0.015 0.018
E 1.62 1.80 0.064 0.070
F 0.44 0.53 0.018 0.020
G
J 0.35 0.44 0.014 0.017
K 0.80 1.04 0.032 0.040
L 300 BSC 0.118 BSC
N 2.04 2.28 0.081 0.089
P 3.94 4.25 0.156 0.167
150 BSC 0.059 BSC
-T-
N
C
J
