TS2938
Taiwan Semiconductor
500mA Ultra Low Dropout Voltage Regulator
With Inhibit Function
DESCRIPTION
The TS2938 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 (200µA Typ.), very low
drop output voltage (Typ. 60mV at light load and 600mV
at 500mA) and output inhibit control. This includes a
tight initial tolerance of 2%, extremely good line
regulation
of
0.05%
typ.,
and
very
low
output
temperature coefficient.
FEATURES
●
●
●
●
●
●
●
●
●
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Dropout voltage typically 0.5V @Io=500mA
Output current up to 500mA
Logic Control Electronic Shutdown
Output voltage trimmed before assembly
-18V Reverse peak voltage
+30V Input over voltage protection
+60V Transient peak voltage
Low Quiescent Current 100µA (Typ.) (On Mode)
Internal current limit
Thermal shutdown protection
APPLICATION
●
Telecommunication
SOP-8
Pin Definition:
1. Output
2. Ground
3. Ground
4. NC
5.
6.
7.
8.
Inhibit
Ground
Ground
Input
Notes:
Moisture sensitivity level: level 3. Per J-STD-020
TYPICAL APPLICATION CIRCUIT
Document Number: DS_P0000209
1
Version: G15
TS2938
Taiwan Semiconductor
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PARAMETER
Input Supply Voltage
(Note 2)
SYMBOL
V
IN
V
OPR
P
D
T
J
T
STG
LIMIT
-18 ~ +60
26
Internally Limited
-40 ~ +125
-65 ~ +150
UNIT
V
V
W
o
o
Operation Input Supply Voltage
Power Dissipation
(Note 3)
Operating Junction Temperature Range
Storage Temperature Range
C
C
THERMAL PERFORMANCE
PARAMETER
Junction to Case Thermal Resistance
SYMBOL
R
ӨJC
LIMIT
20
UNIT
°C/W
Notes:
R
ӨJA
is the sum of the junction-to-case and case-to-ambient thermal resistances. The case thermal reference is defined
at the solder mounting surface of the drain pins. R
ӨJA
is guaranteed by design while R
ӨCA
is determined by the user’s board
design. R
ӨJA
shown below for single device operation on FR-4 PCB in still air.
ELECTRICAL SPECIFICATIONS
(V
IN
=V
OUT
+1V, I
L
=5mA, C
O
=10µF, T
A
=25 C, unless otherwise noted)
PARAMETER
CONDITIONS
T
A
=25
o
C
Output Voltage
T
A
=25~85
o
C
Output Voltage Temperature Coefficient
Line Regulation
Load Regulation
(Note 4)
o
MIN
3.23
4.9
3.17
4.8
--
TYP
3.3
5
3.3
5
50
0.05
0.2
100
300
500
200
12
25
0.9
500
350
120
--
MAX
3.36
5.1
3.43
5.2
150
0.5
1.0
200
400
600
300
20
50
1.3
--
--
--
--
UNIT
V
ppm/ C
%
%
o
Vo+1V
≤
V
IN
≤
26V
5mA
≤
I
L
≤
500mA
I
L
=100mA
--
--
--
--
--
--
--
--
--
--
--
--
60
Dropout Voltage
I
L
=300mA
I
L
=500mA
I
L
=100µA
mV
µA
mA
A
Quiescent Current
(Note 5)
I
L
=300mA
I
L
=500mA
V
OUT
=0
C
L
=2.2µF
C
L
=3.3µF
C
L
=33µF
Ratio
Short Circuit Current
Output Noise,
(Note 6)
10Hz to 100KHz, I
L
=10mA
Ripple Rejection
µVrms
dB
Document Number: DS_P0000209
2
Version: G15
TS2938
Taiwan Semiconductor
ELECTRICAL SPECIFICATIONS
(V
IN
=V
OUT
+1V, I
L
=5mA, C
O
=10µF, T
A
=25 C, unless otherwise noted)
PARAMETER
Shutdown Input
Low (Regulator ON)
Input Logic Voltage
High (Regulator OFF)
V
INHIBIT
= 2.4V
V
INHIBIT
= 26V
V
INHIBIT
≤
2V, V
IN
≤
26V
V
OUT
=0V
--
2.0
--
--
--
1.3
--
30
450
--
0.7
--
50
600
200
µA
V
CONDITIONS
MIN
TYP
MAX
UNIT
o
Shutdown Pin Input Current
Regulator Output Current in Shutdown
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.
2.
Maximum positive supply voltage of 60V must be limited duration (<100ms) and duty cycle (<1%).
3.
The maximum allowable power dissipation is a function of the maximum junction temperature, T
J
, the junction
to ambient thermal resistance, R
ӨJA
, 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 R
ӨJA
can be reduced by using a heatsink.
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.
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.
6.
Output current will decrease with increasing temperature, but it will be not dropped below 500mA at the
maximum specified temperature.
Document Number: DS_P0000209
3
Version: G15
TS2938
Taiwan Semiconductor
ORDERING INFORMATION
VOLTAGE
5.0V
3.3V
PART NO.
TS2938CS50 RLG
TS2938CS33 RLG
PACKAGE
SOP-8
SOP-8
PACKING
2,500pcs / 13” Reel
2,500pcs / 13” Reel
Note:
1. Compliant to RoHS Directive 2011/65/EU and in accordance to WEEE 2002/96/EC.
2. Halogen-free according to IEC 61249-2-21 definition.
BLOCK DIAGRAM
APPLICATION INFORMATION
The TS2938 series is a high performance with low dropout voltage regulator suitable for moderate to high current
and voltage regulator application. Its 500mV (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 V
CE
saturation voltage.
The TS2938 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.
Output Capacitor
The TS2938 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 6.8µF or greater, the output
capacitor should have an ESR less than 2ohm. 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 provide 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.
Document Number: DS_P0000209
4
Version: G15
TS2938
Taiwan Semiconductor
APPLICATION INFORMATION (CONTINUED)
Minimum Load Current
The TS2938 series is specified between finite loads. If the output current is too small leakage currents dominate
and the output voltage rises. A 5mA minimum load current is necessary for proper regulation.
Input Capacitor
An input capacitor of 1µF 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.
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:
I
IN
= I
L
/ I
G
P
D
= (V
IN
-V
OUT
) * I
L
+ (V
IN
) * I
G
Ex. P
D
= (3.3V-2.5V) * 0.5A + 3.3V * 11mA
= 400mW + 36mW
= 436mW
The next parameter which must be calculated the maximum allowable temperature rise.
T
R
(max) is calculated by the using to formula:
T
R
(max) = T
J
(max) – T
A
(max)
o
Where: T
J
(max) is the maximum allowable junction 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
A
(max) and P
D
, the maximum allowable value for the junction to ambient thermal
resistance,
θ
JA
, can now be found:
θ
JA
= T
R
(max) / P
D
Inhibit Input
TS2938 feature an active-low (Inhibit) input that allows ON/OFF control of the regulator. The Inhibit input has
TTL/CMOS compatible thresholds for simple interfacing with logic interfacing. Inhibit should be directly tied to
Ground or keep open (not connected).
Document Number: DS_P0000209
5
Version: G15
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