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Datasheet: TC1014-3.3VCT (TelCom Semiconductor, Inc)

50mA CMOS LDO WITH SHUTDOWN and REFERENCE BYPASS

 

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TelCom Semiconductor, Inc

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TC1014
1
PRELIMINARY INFORMATION
TC1014-01-6/5/97
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
TC1014
FEATURES
s
Zero Ground Current for Longer Battery Life!
s
Very Low Dropout Voltage
s
Guaranteed 50mA Output
s
High Output Voltage Accuracy
s
Standard or Custom Output Voltages
s
Power-Saving Shutdown Mode
s
Reference Bypass Input for Ultra Low-Noise
Operation
s
Over-Current and Over-Temperature Protection
s
Space-Saving SOT-23A-5 Package
s
Pin Compatible Upgrade for MIC5205 and
NSC2980
APPLICATIONS
s
Battery Operated Systems
s
Portable Computers
s
Medical Instruments
s
Instrumentation
s
Cellular / GSM / PHS Phones
s
Linear Post-Regulator for SMPS
s
Pagers
50mA CMOS LDO WITH SHUTDOWN AND REFERENCE BYPASS
TYPICAL APPLICATION
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications to its devices.
GENERAL DESCRIPTION
The TC1014 is a high accuracy (typically
0.5%) CMOS
upgrade for older (bipolar) low dropout regulators such as
the LP2980. Designed specifically for battery-operated sys-
tems, the TC1014's CMOS construction eliminates wasted
ground current, significantly extending battery life. Total
supply current is typically 50
A at full load (
20 to 60 times
lower than in bipolar regulators!).
TC1014 key features include ultra low-noise operation
(plus optional Bypass input); very low dropout voltage
(typically 95mV at full load) and internal feed-forward com-
pensation for fast response to step changes in load. Supply
current is reduced to less than 1
A when the shutdown input
is low. The TC1014 also incorporates both over-tempera-
ture and over-current protection.
The TC1014 is stable with an output capacitor of only
1
F and has a maximum output current of 100mA. For
higher output versions, please see the TC1107, TC1108,
TC1173 (I
OUT
= 300mA) data sheets.
1
F
470pF
Reference
Bypass Cap
(Optional)
Shutdown Control
(from Power Control Logic)
TC1014
V
IN
1
2
3
4
5
V
IN
V
OUT
Bypass
SHDN
GND
V
OUT
PIN CONFIGURATION
ORDERING INFORMATION
Output
Junction
Part No.
Voltage **(V) Package
Temp. Range
TC1014-2.5VCT
2.5
SOT-23A-5* 40
C to +125
C
TC1014-2.7VCT
2.7
SOT-23A-5* 40
C to +125
C
TC1014-3.0VCT
3.0
SOT-23A-5* 40
C to +125
C
TC1014-3.3VCT
3.3
SOT-23A-5* 40
C to +125
C
TC1014-5.0VCT
5.0
SOT-23A-5* 40
C to +125
C
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
** Other output voltages available. Please contact TelCom
Semiconductor for details
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
TC1014
(SOT-23A-5*)
1
3
4
5
2
SHDN
Bypass
GND
V
OUT
V
IN
TOP VIEW
TC1014
2
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1014-01-6/5/97
ABSOLUTE MAXIMUM RATINGS*
Input Voltage ................................................................. 7V
Output Voltage .................................. ( 0.3) to (V
IN
+ 0.3)
Power Dissipation .................... Internally Limited (Note 7)
Operating Temperature .................... 40
C < T
J
< 125
C
Storage Temperature ............................ 65
C to +150
C
Maximum Voltage On Any Pin .......... V
IN
+ 0.3V to 0.3V
*Stresses beyond those listed under "Absolute Maximum Ratings" may
cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond
those indicated in the operational sections of the specifications is not
implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 100
A, C
L
= 3.3
F, SHDN > V
IH
, T
A
= 25
C, unless otherwise noted.
Boldface type specifications apply for junction temperatures of 40
C to +125
C.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
V
IN
Input Operating Voltage
--
--
6.5
V
I
OUTMAX
Maximum Output Current
50
--
--
mA
V
OUT
Output Voltage
Note 1
V
R
2.5%
V
R
0.5%
V
R
+ 2.5%
V
TCV
OUT
V
OUT
Temperature Coefficient
Note 2
20
--
ppm/
C
40
V
OUT
/
V
IN
Line Regulation
(V
R
+ 1V) < V
IN
< 6V
--
0.01
--
%
V
OUT
/V
OUT
Load Regulation
I
L
= 1.0mA to I
OUTMAX
--
0.5
--
%
(Note 3)
V
IN
V
OUT
Dropout Voltage (Note 4)
I
L
= 100
A
--
5
--
mV
I
L
= 20mA
65
I
L
= 50mA
95
(Note 4)
I
GND
Ground Pin Current
I
L
= I
OUTMAX,
(Note 5)
--
--
0
A
I
IN
Supply Current
SHDN = V
IH
, I
L
= 0
--
50
--
A
I
INSD
Shutdown Supply Current
SHDN = 0V
--
--
0.05
A
PSRR
Power Supply Rejection Ratio
F
RE
1kHz
--
64
--
dB
I
OUTSC
Output Short Circuit Current
V
OUT
= 0V
--
200
400
mA
V
OUT
/
P
D
Thermal Regulation
Note 6
--
0.04
--
%/W
eN
Output Noise
I
L
= I
OUTMAX
--
260
--
nV/
Hz
470pF from Bypass to GND
SHDN Input
V
IH
SHDN Input High Threshold
V
IN
= 2.5V to 6.5V
45
--
--
%V
IN
V
IL
SHDN Input Low Threshold
V
IN
= 2.5V to 6.5V
--
--
15
%V
IN
NOTES: 1. V
R
is the regulator output voltage setting. V
R
= 2.5V, 2.7V, 3.0V, 3.3V, 5.0V.
2. TCV
OUT
= (V
OUTMAX
V
OUTMIN
)
x 10
6
V
OUT
x
T
3. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load
range from 1.0mA to the maximum specified output current. Changes in output voltage due to heating effects are covered by the
thermal regulation specification.
4. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value at a 1V
differential.
5. Ground pin current is the regulator pass transistor gate current. The total current drawn from the input supply is the sum of the load
current, ground current and supply current (i.e. I
IN
= I
SUPPLY
+ I
GND
+ I
LOAD
).
6. 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 current pulse equal to I
LMAX
at V
IN
= 6V for T = 10msec.
7. The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable junction temperature and the
thermal resistance from junction-to-air (i.e. T
A
, T
J
,
JA
). Exceeding the maximum allowable power dissipation causes the device to
initiate thermal shutdown. Please see
Thermal Considerations section of this data sheet for more details.
.
TC1014
3
PRELIMINARY INFORMATION
TC1014-01-6/5/97
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
Pin No.
1
V
IN
Unregulated supply input.
2
GND
Ground terminal.
3
SHDN
Shutdown control input. The regulator is fully enabled when a logic high is applied to this
input. The regulator enters shutdown when a logic low is applied to this input. During
shutdown, output voltage falls to zero, and supply current is reduced to under 1 microamp
(typical).
4
Bypass
Reference bypass input. Connecting a 470pF to this input further reduces output noise.
5
V
OUT
Regulated voltage output.
PIN DESCRIPTION
(SOT-23A-5)
Symbol
Description
DETAILED DESCRIPTION
The TC1014 is a precision fixed output voltage regula-
tor. (If an adjustable version is desired, please see the
TC1070 or TC1071 data sheets.) Unlike the bipolar regula-
tors, the TC1014 supply current does not increase with load
current. In addition, V
OUT
remains stable and within regula-
tion at very low load currents (an important consideration in
RTC and CMOS RAM battery back-up applications).
Figure 1 shows a typical application circuit. The regula-
tor is enabled any time the shutdown input (SHDN) is at or
above V
IH
, and shutdown (disabled) when SHDN is at or
below V
IL
. SHDN may be controlled by a CMOS logic gate,
or I/O port of a microcontroller. If the SHDN input is not
required, it should be connected directly to the input supply.
While in shutdown, supply current decreases to 0.05
A
(typical) and V
OUT
falls to zero volts.
Bypass Input
A 470pF capacitor connected from the Bypass input to
ground reduces noise present on the internal reference,
which in turn significantly reduces output noise. If output
noise is not a concern, this input may be left unconnected.
Larger capacitor values may be used, but results in a longer
time period to rated output voltage when power is initially
applied.
Output Capacitor
A 1
F (min) capacitor from V
OUT
to ground is recom-
mended. The output capacitor should have an effective
series resistance of 5
or less, and a resonant frequency
above 1MHz. A 1
F capacitor should be connected from V
IN
to GND if there is more than 10 inches of wire between the
regulator and the AC filter capacitor, or if a battery is used as
the power source. Aluminum electrolytic or tantalum capaci-
tor types can be used. (Since many aluminum electrolytic
capacitors freeze at approximately 30
C, solid tantalums
are recommended for applications operating below 25
C.)
When operating from sources other than batteries, supply-
noise rejection and transient response can be improved by
increasing the value of the input and output capacitors and
employing passive filtering techniques.
Thermal Considerations
Thermal Shutdown
Integrated thermal protection circuitry shuts the regula-
tor off when die temperature exceeds 160
C. The regulator
remains off until the die temperature drops to approximately
150
C.
Power Dissipation
The amount of power the regulator dissipates is prima-
rily a function of input and output voltage, and output current.
The following equation is used to calculate worst case
actual power dissipation:
Figure 1. Typical Application Circuit
1
F
470pF
Reference
Bypass Cap
(Optional)
Shutdown Control
(to CMOS Logic or Tie to V
IN
if Unused)
TC1014
V
IN
BATTERY
V
OUT
Bypass
SHDN
GND
V
OUT
1
F
TC1014
4
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1014-01-6/5/97
P
D
(V
INMAX
V
OUTMIN
)I
LOADMAX
Where:
P
D
= Worst case actual power dissipation
V
INMAX
= Maximum voltage on V
IN
V
OUTMIN
= Minimum regulator output voltage
I
LOADMAX
= Maximum output (load) current
Equation 1.
The maximum
allowable power dissipation (Equation 2)
is a function of the maximum ambient temperature (T
AMAX
),
the maximum allowable die temperature (125
C) and the
thermal resistance from junction-to-air (
JA
). The
SOT-23A-5 package has a
JA
of approximately
220
C/Watt
when mounted on a single layer FR4 dielectric copper clad
PC board.
P
D MAX
= (T
JMAX
T
JMAX)
JA
Where all terms are previously defined.
Equation 2.
Equation 1 can be used in conjunction with Equation 2
to ensure regulator thermal operation is within limits. For
example:
Given:
V
INMAX
= 3.0V
5%
V
OUTMIN
= 2.7V
0.5V
I
LOAD
= 40mA
T
AMAX
= 55
C
Find:
1. Actual power dissipation
2. Maximum allowable dissipation
Actual power dissipation:
P
D
(V
INMAX
V
OUTMIN
)I
LOADMAX
= [(3.0 x 1.1) (2.7 x .995)]40 x 10
3
= 18.5mW
Maximum allowable power dissipation:
P
DMAX
= (T
JMAX
T
AMAX
)
JA
= (125 55)
220
= 318mW
In this example, the TC1014 dissipates a maximum of
only 60mW; far below the allowable limit of 318mW. In a
similar manner, Equation 1 and Equation 2 can be used to
calculate maximum current and/or input voltage limits. For
example, the maximum allowable V
IN
is found by sustituting
the maximum allowable power dissipation of 318mW into
Equation 1, from which V
INMAX
= 5.9V.
Layout Considerations
The primary path of heat conduction out of the package
is via the package leads. Therefore, layouts having a
ground plane, wide traces at the pads, and wide power
supply bus lines combine to lower
JA
and, therefore,
increase the maximum allowable power dissipation limit.
TC1014
5
PRELIMINARY INFORMATION
TC1014-01-6/5/97
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
Sales Offices
TelCom Semiconductor
1300 Terra Bella Avenue
P.O. Box 7267
Mountain View, CA 94039-7267
TEL: 415-968-9241
FAX: 415-967-1590
E-Mail: liter@c2smtp.telcom-semi.com
Printed in the U.S.A.
TelCom Semiconductor H.K. Ltd.
10 Sam Chuk Street, 6/F
San Po Kong
Kowloon
Hong Kong
TEL: 852-2324-0122
FAX: 852-2354-9957
TelCom Semiconductor
Austin Product Center
9101 Burnet Rd. Suite 214
Austin, TX 78758
TEL: 512-873-7100
FAX: 512-873-8236
SOT-23A-5*
PACKAGE DIMENSIONS
Dimensions: inches (mm)
.071 (1.80)
.059 (1.50)
.122 (3.10)
.098 (2.50)
.020 (0.50)
.012 (0.30)
.037 (0.95)
REFERENCE
.122 (3.10)
.106 (2.70)
.057 (1.45)
.035 (0.90)
.006 (0.15)
.000 (0.00)
.022 (0.55)
.008 (0.20)
10
MAX.
.010 (0.25)
.004 (0.09)
SOT-23A-5
&
= part number code + temperature range and voltage
TC1014 (V)
Code
2.5
A1
2.7
A2
3.0
A3
3.3
A5
5.0
A7
represents year and quarter code
represents lot ID number
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
MARKING
TC1015
1
PRELIMINARY INFORMATION
TC1015-01-6/5/97
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
TC1015
FEATURES
s
Zero Ground Current for Longer Battery Life!
s
Very Low Dropout Voltage
s
Guaranteed 100mA Output
s
High Output Voltage Accuracy
s
Standard or Custom Output Voltages
s
Power-Saving Shutdown Mode
s
Reference Bypass Input for Ultra Low-Noise
Operation
s
Over-Current and Over-Temperature Protection
s
Space-Saving SOT-23A-5 Package
s
Pin Compatible Upgrade for MIC5205 and
NSC2980
APPLICATIONS
s
Battery Operated Systems
s
Portable Computers
s
Medical Instruments
s
Instrumentation
s
Cellular / GSM / PHS Phones
s
Linear Post-Regulator for SMPS
s
Pagers
100mA CMOS LDO WITH SHUTDOWN AND REFERENCE BYPASS
TYPICAL APPLICATION
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications to its devices.
GENERAL DESCRIPTION
The TC1015 is a high accuracy (typically
0.5%) CMOS
upgrade for older (bipolar) low dropout regulators such as
the LP2980. Designed specifically for battery-operated sys-
tems, the TC1015's CMOS construction eliminates wasted
ground current, significantly extending battery life. Total
supply current is typically 50
A at full load (
20 to 60 times
lower than in bipolar regulators!).
TC1015 key features include ultra low-noise operation
(plus optional Bypass input); very low dropout voltage (typi-
cally 200mV at full load) and internal feed-forward compen-
sation for fast response to step changes in load. Supply
current is reduced to 0.05
A and V
OUT
is disabled when the
shutdown input is low. The TC1015 also incorporates both
over-temperature and over-current protection.
The TC1015 is stable with an output capacitor of only
1
F and has a maximum output current of 100mA. For
higher output versions, please see the TC1107, TC1108,
TC1173 (I
OUT
= 300mA) data sheets.
1
F
470pF
Reference
Bypass Cap
(Optional)
Shutdown Control
(from Power Control Logic)
TC1015
V
IN
1
2
3
4
5
V
IN
V
OUT
Bypass
SHDN
GND
V
OUT
PIN CONFIGURATION
ORDERING INFORMATION
Output
Junction
Part No.
Voltage **(V) Package
Temp. Range
TC1015-2.5VCT
2.5
SOT-23A-5* 40
C to +125
C
TC1015-2.7VCT
2.7
SOT-23A-5* 40
C to +125
C
TC1015-3.0VCT
3.0
SOT-23A-5* 40
C to +125
C
TC1015-3.3VCT
3.3
SOT-23A-5* 40
C to +125
C
TC1015-5.0VCT
5.0
SOT-23A-5* 40
C to +125
C
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
** Other output voltages available. Please contact TelCom
Semiconductor for details
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
TC1015
(SOT-23A-5*)
TOP VIEW
1
3
4
5
2
SHDN
Bypass
GND
V
OUT
V
IN
TC1015
2
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1015-01-6/5/97
ABSOLUTE MAXIMUM RATINGS*
Input Voltage ................................................................. 7V
Output Voltage .................................. ( 0.3) to (V
IN
+ 0.3)
Power Dissipation .................... Internally Limited (Note 7)
Operating Temperature .................... 40
C < T
J
< 125
C
Storage Temperature ............................ 65
C to +150
C
Maximum Voltage On Any Pin .......... V
IN
+ 0.3V to 0.3V
*Stresses beyond those listed under "Absolute Maximum Ratings" may
cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond
those indicated in the operational sections of the specifications is not
implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 100
A, C
L
= 3.3
F, SHDN > V
IH
, T
A
= 25
C, unless otherwise noted.
Boldface type specifications apply for junction temperatures of 40
C to +125
C.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
V
IN
Input Operating Voltage
--
--
6.5
V
I
OUTMAX
Maximum Output Current
100
--
--
mA
V
OUT
Output Voltage
Note 1
V
R
2.5%
V
R
0.5%
V
R
+ 2.5%
V
TCV
OUT
V
OUT
Temperature Coefficient
Note 2
20
--
ppm/
C
40
V
OUT
/
V
IN
Line Regulation
(V
R
+ 1V) < V
IN
< 6V
--
0.01
--
%
V
OUT
/V
OUT
Load Regulation
I
L
= 1.0mA to I
OUTMAX
--
0.5
--
%
(Note 3)
V
IN
V
OUT
Dropout Voltage (Note 4)
I
L
= 0.1mA
--
20
--
mV
I
L
= 20mA
70
I
L
= 50mA
93
I
L
=100mA
112
(Note 4)
I
GND
Ground Pin Current
I
L
= I
OUTMAX,
(Note 5)
--
--
0
A
I
IN
Supply Current
SHDN = V
IH
, I
L
= 0
--
50
--
A
I
INSD
Shutdown Supply Current
SHDN = 0V
--
--
0.05
A
PSRR
Power Supply Rejection Ratio
F
RE
1kHz
--
64
--
dB
I
OUTSC
Output Short Circuit Current
V
OUT
= 0V
--
300
500
mA
V
OUT
/
P
D
Thermal Regulation
Note 6
--
0.04
--
%/W
eN
Output Noise
I
L
= I
OUTMAX
--
260
--
nV/
Hz
470pF from Bypass to GND
SHDN Input
V
IH
SHDN Input High Threshold
V
IN
= 2.5V to 6.5V
45
--
--
%V
IN
V
IL
SHDN Input Low Threshold
V
IN
= 2.5V to 6.5V
--
--
15
%V
IN
NOTES: 1. V
R
is the regulator output voltage setting. V
R
= 2.5V, 2.7V, 3.0V, 3.3V, 5.0V.
2. TCV
OUT
= (V
OUTMAX
V
OUTMIN
)
x 10
6
V
OUT
x
T
3. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load
range from 1.0mA to the maximum specified output current. Changes in output voltage due to heating effects are covered by the
thermal regulation specification.
4. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value at a 1V
differential.
5. Ground pin current is the regulator pass transistor gate current. The total current drawn from the input supply is the sum of the load
current, ground current and supply current (i.e. I
IN
= I
SUPPLY
+ I
GND
+ I
LOAD
).
6. 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 current pulse equal to I
LMAX
at V
IN
= 6V for T = 10msec.
7. The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable junction temperature and the
thermal resistance from junction-to-air (i.e. T
A
, T
J
,
JA
). Exceeding the maximum allowable power dissipation causes the device to
initiate thermal shutdown. Please see
Thermal Considerations section of this data sheet for more details.
.
TC1015
3
PRELIMINARY INFORMATION
TC1015-01-6/5/97
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
Pin No.
1
V
IN
Unregulated supply input.
2
GND
Ground terminal.
3
SHDN
Shutdown control input. The regulator is fully enabled when a logic high is applied to this
input. The regulator enters shutdown when a logic low is applied to this input. During
shutdown, output voltage falls to zero, and supply current is reduced to under 1 microamp
(typical).
4
Bypass
Reference bypass input. Connecting a 470pF to this input further reduces output noise.
5
V
OUT
Regulated voltage output.
PIN DESCRIPTION
(SOT-23A-5)
Symbol
Description
DETAILED DESCRIPTION
The TC1015 is a precision fixed output voltage regula-
tor. (If an adjustable version is desired, please see the
TC1070 or TC1071 data sheets.) Unlike the bipolar regula-
tors, the TC1015 supply current does not increase with load
current. In addition, V
OUT
remains stable and within regula-
tion at very low load currents (an important consideration in
RTC and CMOS RAM battery back-up applications).
Figure 1 shows a typical application circuit. The regula-
tor is enabled any time the shutdown input (SHDN) is at or
above V
IH
, and shutdown (disabled) when SHDN is at or
below V
IL
. SHDN may be controlled by a CMOS logic gate,
or I/O port of a microcontroller. If the SHDN input is not
required, it should be connected directly to the input supply.
While in shutdown, supply current decreases to 0.05
A
(typical) and V
OUT
falls to zero volts.
Bypass Input
A 470pF capacitor connected from the Bypass input to
ground reduces noise present on the internal reference,
which in turn significantly reduces output noise. If output
noise is not a concern, this input may be left unconnected.
Larger capacitor values may be used, but results in a longer
time period to rated output voltage when power is initially
applied.
Output Capacitor
A 1
F (min) capacitor from V
OUT
to ground is recom-
mended. The output capacitor should have an effective
series resistance of 5
or less, and a resonant frequency
above 1MHz. A 1
F capacitor should be connected from V
IN
to GND if there is more than 10 inches of wire between the
regulator and the AC filter capacitor, or if a battery is used as
the power source. Aluminum electrolytic or tantalum capaci-
tor types can be used. (Since many aluminum electrolytic
capacitors freeze at approximately 30
C, solid tantalums
are recommended for applications operating below 25
C.)
When operating from sources other than batteries, supply-
noise rejection and transient response can be improved by
increasing the value of the input and output capacitors and
employing passive filtering techniques.
Thermal Considerations
Thermal Shutdown
Integrated thermal protection circuitry shuts the regula-
tor off when die temperature exceeds 160
C. The regulator
remains off until the die temperature drops to approximately
150
C.
Power Dissipation
The amount of power the regulator dissipates is prima-
rily a function of input and output voltage, and output current.
The following equation is used to calculate worst case
actual power dissipation:
Figure 1. Typical Application Circuit
1
F
470pF
Reference
Bypass Cap
(Optional)
Shutdown Control
(to CMOS Logic or Tie to V
IN
if Unused)
TC1015
V
IN
BATTERY
V
OUT
Bypass
SHDN
GND
V
OUT
1
F
TC1015
4
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1015-01-6/5/97
P
D
(V
INMAX
V
OUTMIN
)I
LOADMAX
Where:
P
D
= Worst case actual power dissipation
V
INMAX
= Maximum voltage on V
IN
V
OUTMIN
= Minimum regulator output voltage
I
LOADMAX
= Maximum output (load) current
Equation 1.
The maximum
allowable power dissipation (Equation 2)
is a function of the maximum ambient temperature (T
AMAX
),
the maximum allowable die temperature (125
C) and the
thermal resistance from junction-to-air (
JA
). The
SOT-23A-5 package has a
JA
of approximately
220
C/Watt
when mounted on a single layer FR4 dielectric copper clad
PC board.
P
D MAX
= (T
JMAX
T
JMAX)
JA
Where all terms are previously defined.
Equation 2.
Equation 1 can be used in conjunction with Equation 2
to ensure regulator thermal operation is within limits. For
example:
Given:
V
INMAX
= 3.0V
10%
V
OUTMIN
= 2.7V
0.5V
I
LOAD
= 98mA
T
AMAX
= 55
C
Find:
1. Actual power dissipation
2. Maximum allowable dissipation
Actual power dissipation:
P
D
(V
INMAX
V
OUTMIN
)I
LOADMAX
= [(3.0 x 1.1) (2.7 x .995)]98 x 10
3
= 60mW
Maximum allowable power dissipation:
P
DMAX
= (T
JMAX
T
AMAX
)
JA
= (125 55)
220
= 318mW
In this example, the TC1015 dissipates a maximum of
only 60mW; far below the allowable limit of 318mW. In a
similar manner, Equation 1 and Equation 2 can be used to
calculate maximum current and/or input voltage limits. For
example, the maximum allowable V
IN
is found by sustituting
the maximum allowable power dissipation of 318mW into
Equation 1, from which V
INMAX
= 5.9V.
Layout Considerations
The primary path of heat conduction out of the package
is via the package leads. Therefore, layouts having a
ground plane, wide traces at the pads, and wide power
supply bus lines combine to lower
JA
and, therefore,
increase the maximum allowable power dissipation limit.
TC1015
5
PRELIMINARY INFORMATION
TC1015-01-6/5/97
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
Sales Offices
TelCom Semiconductor
1300 Terra Bella Avenue
P.O. Box 7267
Mountain View, CA 94039-7267
TEL: 415-968-9241
FAX: 415-967-1590
E-Mail: liter@c2smtp.telcom-semi.com
Printed in the U.S.A.
TelCom Semiconductor H.K. Ltd.
10 Sam Chuk Street, 6/F
San Po Kong
Kowloon
Hong Kong
TEL: 852-2324-0122
FAX: 852-2354-9957
TelCom Semiconductor
Austin Product Center
9101 Burnet Rd. Suite 214
Austin, TX 78758
TEL: 512-873-7100
FAX: 512-873-8236
SOT-23A-5*
PACKAGE DIMENSIONS
Dimensions: inches (mm)
.071 (1.80)
.059 (1.50)
.122 (3.10)
.098 (2.50)
.020 (0.50)
.012 (0.30)
.037 (0.95)
REFERENCE
.122 (3.10)
.106 (2.70)
.057 (1.45)
.035 (0.90)
.006 (0.15)
.000 (0.00)
.022 (0.55)
.008 (0.20)
10
MAX.
.010 (0.25)
.004 (0.09)
SOT-23A-5
&
= part number code + temperature range and voltage
TC1015 (V)
Code
2.5
B1
2.7
B2
3.0
B3
3.3
B5
5.0
B7
represents year and quarter code
represents lot ID number
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
MARKING
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