TS2940
1A Ultra Low Dropout Fixed Positive Voltage Regulator
TO-263
Low Dropout Voltage 0.6V (typ.)
Pin assignment:
1. Input
2. Ground
3. Output
General Description
The TS2940 series of fixed-voltage monolithic micro-power voltage regulators is designed for a wide range of
applications. This device excellent choice of use in battery-power application. Furthermore, the quiescent current
increases on slightly at dropout, which prolongs battery life.
This series of fixed-voltage regulators features very low ground current (100uA Typ.) and very low drop output voltage
(Typ. 60mV at light load and 600mV at 1A). This includes a tight initial tolerance of 1% typ., extremely good line regulation
of 0.05% typ., and very low output temperature coefficient.
This series is offered in 3-pin TO-263, TO-220, TO-252 & SOT-223 package.
Features
Dropout voltage typically 0.6V @Io=1A
Output current up to 1A
Output voltage trimmed before assembly
-18V Reverse peak voltage
+30V Input over voltage protection
+60V Transient peak voltage
Internal current limit
Thermal shutdown protection
Block Diagram
Ordering Information
Part No.
TS2940CZxx
TS2940CMxx
TS2940CPxx
-40 ~ +85 C
o
Operation Temp.
-40 ~ +125 C
o
Package
TO-220
TO-263
TO-252
TS2940CWxx
SOT-223
Note: Where
xx
denotes voltage option, available are
5.0V, 3.3V, 2.5V and 1.8V. Contact factory for
additional voltage options.
Absolute Maximum Rating
(Note 1)
Input Supply Voltage (Note 2)
Operation Input Supply Voltage
Power Dissipation (Note 3)
Operating Junction Temperature Range
Storage Temperature Range
Lead Soldering Temperature (260 C)
TO-220 TO-263 Package
TO-252 / SOT-223Package
5
4
S
o
Vin
Vin (operate)
P
D
T
J
T
STG
-18 ~ +60
30V
Internally Limited
-40 ~ +125
-65 ~ +150
V
V
W
o
o
C
C
TS2940
1-6
2003/12 rev. B
Electrical Characteristics
Vin = Vout + 5V, I
L
= 5mA, C
o
= 10uF, Ta = 25
o
C, unless otherwise specified.
Parameter
Output Voltage
Output Voltage
Conditions
5mA
≤
I
L
≤
1A,
Vo+5V
≤
Vin
≤
26V
Min
0.980|Vo|
0.970|Vo|
Typ
5.0 / 3.3
2.5 / 1.8
Max
1.020|Vo|
1.030|Vo|
Unit
V
V
Input Supply Voltage
Output Voltage Temperature
Coefficient
Line Regulation
Load Regulation
Dropout Voltage (Note 4)
Vo+2V
≤
Vin
≤
26V
5mA
≤
I
L
≤
1A
I
L
=100mA
I
L
=500mA
I
L
=800mA
Quiescent Current (Note 5)
I
L
=5mA
I
L
=800mA
Short Circuit Current (Note 6)
Output Noise,
10Hz to 100KHz, I
L
=10mA
Vout=0
C
L
=2.2uF
C
L
=3.3uF
C
L
=33uF
--
--
--
50
26
150
V
ppm/ C
o
--
--
--
--
--
--
--
--
--
--
--
0.05
0.2
100
300
600
10
30
--
500
350
120
0.5
1.0
200
500
800
--
--
1.5
--
--
--
%
%
mV
mA
A
uVrms
Thermal Performance
Condition
Thermal Resistance
Junction to Ambient
Package type
TO-220
TO-263
TO-252
SOT-223
Typ
60
80
150
170
Unit
o
C/W
Note 1: Absolute Maximum Rating is limits beyond which damage to the device may occur. For guaranteed specifications
and test conditions see the Electrical Characteristics.
Note 2: Maximum positive supply voltage of 60V must be limited duration (<100mS) and duty cycle (<1%).
Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, Tj, the junction to
ambient thermal resistance,
θja,
and the ambient temperature, Ta. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. The effective
value of
θja
can be reduced by using a heatsink.
Note 4: 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 5: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the
ground pin current and output load current.
Note 6: Output current will decrease with increasing temperature, but it will be not dropped below 1A at the maximum
specified temperature.
TS2940
2-6
2003/12 rev. B
Application Information
The TS2940 series is a high performance with low dropout
voltage regulator suitable for moderate to high current and
voltage regulator application. Its 600mA(typ) dropout
voltage at full load and over temperature makes it
especially valuable in battery power systems and as high
efficiency noise filters in post regulator applications. Unlike
normal NPN transistor design, where the base to emitter
voltage drop and collector to emitter saturation voltage limit
the minimum dropout voltage, dropout performance of the
PNP output of these devices is limited only by low Vce
saturation voltage.
The TS2940 series is fully protected from damage due to
fault conditions. Linear current limiting is provided. Output
current during overload conditions is constant. Thermal
shutdown the device when the die temperature exceeds the
maximum safe operating temperature. Transient protection
allows device 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.
A low ESR solid tantalum capacitor works extremely
well and provides good transient response and
stability over temperature. Aluminum electrolytic can
also be used, as long as the ESR of the capacitor is
<2ohm. The value of the output capacitor can be
increased without limit. Higher capacitance values
help to improved transient response and ripple
rejection and reduce output noise.
Minimum Load Current
The TS2940 series is specified between finite loads.
If the output current is too small leakage currents
dominate and the output voltage rises. A 10mA
minimum load current is necessary for proper
regulation.
Input Capacitor
An input capacitor of 1uF or greater is recommended
when the device is more that 4 inches away from the
bulk AC supply capacitance or when the supply is a
battery. Small and surface mount ceramic chip
capacitors can be used for bypassing. Larger values
will help to improve ripple rejection by bypassing the
input to the regulator, further improving the integrity of
the output voltage.
Typical Application Circuit
Thermal Characteristics
A heatsink may be required depending on the
maximum power dissipation and maximum ambient
temperature of the application. Under all possible
operating conditions, the junction temperature must
be within the range specified under absolute
maximum ratings. To determine if the heatsink is
required, the power dissipated by the regulator, P
D
must be calculated.
The below formula shows the voltages and currents
for calculating the P
D
in the regulator:
Iin = I
L
/ I
G
P
D
= (Vin-Vout) * I
L
+ (Vin) * I
G
Ex. P
D
= (3.3V-2.5V) * 1A + 3.3V * 11mA
= 800mW + 36mW
= 836mW
Remark: I
L
is output load current,
I
G
is ground current.
Vin is input voltage
Vout is output voltage
Output Capacitor
The TS2940 series requires an output capacitor to maintain
stability and improve transient response. Proper capacitor
selection is important to ensure proper operation. The
output capacitor selection is dependent upon the ESR of
the output capacitor the maintain stability. When the output
capacitor is 10uF or greater, the output capacitor should
have an ESR less than 2 ohm. This will improve transient
response as well as promoted stability. Ultra low ESR
capacitors (<100mohm), such as ceramic chip capacitors
may promote instability. These very low ESR levels may
cause an oscillation and/or under damped transient
response.
TS2940
3-6
2003/12 rev. B
Application Information (continued)
The next parameter which must be calculated is the
maximum allowable temperature rise, T
R
(max). this is
calculated by the using to formula:
T
R
(max) = T
J
(max) – T
A
(max)
Where: T
J
(max) is the maximum allowable junction
temperature, which is 125
o
C for commercial
grade parts.
T
A
(max) is the maximum ambient temperature
which will be encountered in the application.
Using the calculated values for T
R
(max) and P
D
, the
maximum allowable value for the junction to ambient
thermal resistance,
θja,
can now be found:
θja
= T
R
(max) / P
D
IMPORTANT: if the maximum allowable value for is
found to be
≥60
o
C/W for the TO-220 package,
≥80
o
C/W
for the TO-263 package,
≥150
o
C/W for the TO-252
package, or
≥170
o
C/W for the SOT-223 package, no
heatsink is needed since the package alone will dissipate
enough heat to satisfy these requirements. If the
calculated value for
θja
falls below these limits, a
heatsink is required.
TS2940
4-6
2003/12 rev. B
TO-220 Mechanical Drawing
A
B
C
K
L
DIM
TO-220 DIMENSION
MILLIMETERS
MIN
MAX
10.000
3.240
2.440
-
0.381
2.345
4.690
12.700
8.382
14.224
3.556
0.508
27.700
2.032
0.255
5.842
10.500
4.440
2.940
6.350
1.106
2.715
5.430
14.732
9.017
16.510
4.826
1.397
29.620
2.921
0.610
6.858
INCHES
MIN
MAX
0.394
0.128
0.096
-
0.015
0.092
0.092
0.500
0.330
0.560
0.140
0.020
1.060
0.080
0.010
0.230
0.413
0.175
0.116
0.250
0.040
0.058
0.107
0.581
0.355
0.650
0.190
0.055
1.230
0.115
0.024
0.270
P
A
B
C
D
J
I
M
E
F
G
H
I
J
K
L
M
N
D
H
F
G
E
O
N
O
P
TO-263 Mechanical Drawing
A
TO-263 DIMENSION
E
F
DIM
A
B
C
MILLIMETERS
MIN
MAX
10.000
14.605
0.508
2.420
4.064
1.118
0.450
8.280
1.140
1.480
10.500
15.875
0.991
2.660
4.830
1.400
0.730
8.800
1.400
1.520
INCHES
MIN
MAX
0.394
0.575
0.020
0.095
0.160
0.045
0.018
0.325
0.044
0.058
0.413
0.625
0.039
0.105
0.190
0.055
0.029
0.346
0.055
0.060
B
I
H
D
E
F
G
H
I
C
D
G
J
TS2940
5-6
2003/12 rev. B
微控制器 MCU
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