TS2937
500mA Ultra Low Dropout Fixed Positive Voltage Regulator
TO-263
Low Dropout Voltage 0.6V max.
Pin assignment:
1. Input
2. Ground
3.
Output
General Description
T
he TS2937 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 500mA). 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=500mA
Output current up to 500mA
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.
TS2937CZxx
TS2937CMxx
TS2937CPxx
o
-20 ~ +85 C
Operation Temp.
(Ambient)
Package
TO-220
TO-263
TO-252
SOT-223
TS2937CWxx
Note: Where
xx
denotes voltage option, available are
12V, 10V, 8V, 5V, 3.3V and 2.5V. 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
o
C)
TO-220 / TO-263 Package
TO-252 / SOT-223 Package
5
4
S
Vin
Vin (operate)
P
D
T
J
T
STG
-18 ~ +60
26
Internally Limited
-25 ~ +125
-65 ~ +150
V
V
W
o
o
C
C
TS2937
1-1
2003/12 rev. B
Electrical Characteristics
Vin = Vout + 1V, I
L
= 5mA, C
o
= 10uF, Ta = 25
o
C, unless otherwise specified.
Parameter
Output Voltage
Output Voltage
Conditions
5mA
≤
I
L
≤
500mA,
Vo+1V
≤
Vin
≤
26V
Min
0.980|Vo|
0.970|Vo|
Typ
Vout
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+1V
≤
Vin
≤
26V
5mA
≤
I
L
≤
500mA
I
L
=100mA
I
L
=300mA
I
L
=500mA
Quiescent Current (Note 5)
I
L
=100uA
I
L
=300mA
I
L
=500mA
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/
o
C
--
--
--
--
--
--
--
--
--
--
--
--
0.05
0.2
100
300
500
100
12
25
--
500
350
120
0.5
1.0
200
400
600
--
--
--
1.3
--
--
--
%
%
mV
uA
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 500mA at the maximum
specified temperature.
TS2937
2-2
2003/12 rev. B
Application Information
The TS2937 series is a high performance with low dropout
voltage regulator suitable for moderate to high current and
voltage regulator application. Its 600mV(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 TS2937 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.
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 TS2937 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) * 0.5A + 3.3V * 11mA
= 400mW + 36mW
= 436mW
Remark: I
L
is output load current,
I
G
is ground current.
Vin is input voltage
Vout is output voltage
The next parameter which must be calculated is the
maximum allowable temperature rise.
Output Capacitor
The TS2937 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. A low ESR solid
tantalum capacitor works extremely well and provides
good transient response and stability over
TS2937
3-3
2003/12 rev. B
Application Information (continued)
T
R
(max) 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
o
temperature, which is 125 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
o
found to be
≥60
C/W for the TO-220 package,
≥80
o
o
C/W for the TO-263 package,
≥150
C/W for the
o
TO-252 package, or
≥170
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.
TS2937
4-4
2003/12 rev. B
TO-220 Mechanical Drawing
A
B
C
K
L
DIM
TO-220 DIMENSION
MILLIMETERS
INCHES
MIN
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
MAX
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
MIN
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
MAX
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
J
I
M
D
H
F
G
E
O
N
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
TO-263 Mechanical Drawing
A
E
F
DIM
A
B
C
D
E
F
G
H
I
J
B
I
H
C
D
G
TO-263 DIMENSION
MILLIMETERS
INCHES
MIN
MAX
MIN
MAX
10.000
10.500
0.394
0.413
14.605
15.875
0.575
0.625
0.508
0.991
0.020
0.039
2.420
2.660
0.095
0.105
4.064
4.830
0.160
0.190
1.118
1.400
0.045
0.055
0.450
0.730
0.018
0.029
8.280
8.800
0.325
0.346
1.140
1.400
0.044
0.055
1.480
1.520
0.058
0.060
TS2937
5-5
2003/12 rev. B
51单片机
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