Document Outline
- Return to Contents
- TC1054
- List of Figures
- 1. Typical Application Circuit
- 2. ERROR Output Operation
- Features
- Applications
- Ordering Information
- Pin Configuration
- General Description
- Typical Application
- Absolute Maximum Ratings
- Electrical Characteristics
- Electrical Characteristics
- Pin Description
- Detailed Description
- ERROR Open Drain Output
- Output Capacitor
- Thermal Considerations
- Markings
- Package Dimensions
- Sales Offices
- TC1055
- List of Figures
- 1. Typical Application Circuit
- 2. ERROR Output Operation
- Features
- Applications
- Ordering Information
- Pin Configuration
- General Description
- Typical Application
- Absolute Maximum Ratings
- Electrical Characteristics
- Electrical Characteristics
- Pin Description
- Detailed Description
- ERROR Open Drain Output
- Output Capacitor
- Thermal Considerations
- Markings
- Package Dimensions
- Sales Offices
TC1054
1
PRELIMINARY INFORMATION
TC1054-01 6/12/97
50mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
GENERAL DESCRIPTION
The TC1054 is a high accuracy (typically
0.5%) CMOS
upgrade for older (bipolar) low dropout regulators. De-
signed specifically for battery-operated systems, the
TC1054'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!).
TC1054 key features include ultra low noise operation,
very low dropout voltage (typically 100mV at full load) and
internal feed-forward compensation for fast response to
step changes in load. An error output (ERROR) is asserted
when the TC1054 is out-of-regulation (due to a low input
voltage or excessive output current). ERROR can be used
as a low battery warning or as a processor RESET signal
(with the addition of an external RC network). Supply current
is reduced to less than 1
A, and both V
OUT
and ERROR
are disabled when the shutdown input is low. The TC1054
incorporates both over-temperature and over-current pro-
tection.
The TC1054 is stable with an output capacitor of only
1
F and has a maximum output current of 50mA. For higher
output current regulators, please see the TC1055
(I
OUT
= 100mA) regulator and TC1107, TC1108 (I
OUT
=
300mA) data sheets.
50mA CMOS LDO WITH SHUTDOWN AND ERROR OUTPUT
TC1054
PIN CONFIGURATION
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
ERROR Output can be Used as a Low Battery
Detector, or Processor Reset Generator
s
Over-Current and Over-Temperature Protection
s
Space-Saving SOT-23A-5 Package
s
Pin Compatible Upgrades for Bipolar Regulators
APPLICATIONS
s
Battery Operated Systems
s
Portable Computers
s
Medical Instruments
s
Instrumentation
s
Cellular/GSMS/PHS Phones
s
Linear Post-Regulators for SMPS
s
Pagers
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices
TYPICAL APPLICATION
TC1054
(SOT-23A-5*)
TOP VIEW
2
SHDN
ERROR
GND
V
OUT
V
IN
4
5
3
1
ORDERING INFORMATION
Output
Junction
Part No.
Voltage **(V) Package
Temp. Range
TC1054-2.5VCT
2.5
SOT-23A-5* 40
C to +125
C
TC1054-2.7VCT
2.7
SOT-23A-5* 40
C to +125
C
TC1054-3.0VCT
3.0
SOT-23A-5* 40
C to +125
C
TC1054-3.3VCT
3.3
SOT-23A-5* 40
C to +125
C
TC1054-5.0VCT
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
1
F
Shutdown Control
(from Power Control Logic)
TC1054
V
IN
1
2
3
4
5
V
IN
V
OUT
ERROR
SHDN
GND
1M
V
OUT
ERROR
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
TC1054
50mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
2
PRELIMINARY INFORMATION
TC1054-01 6/12/97
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 0.1mA, 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
TC V
OUT
V
OUT
Temperature Coefficient
Note 2
--
--
--
ppm/
C
40
V
OUT
/
V
IN
Line Regulation
(V
R
+ 1V) < V
IN
< 6V
--
0.01
0.05
%/V
V
OUT
/V
OUT
Load Regulation
I
L
= 0.1mA to I
OUTMAX
--
0.5
--
%
(Note 3)
V
IN
V
OUT
Dropout Voltage
I
L
= 0.1mA
--
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
R
OUT
Output Resistance during Shutdown
SHDN < V
IL
100 x V
R
160 x V
R
--
k
PSRR
Power Supply Rejection Ratio
F
RE
1kHz
--
64
--
dB
I
OUTSC
Output Short Circuit Current
V
OUT
= 0V
--
200
450
mA
V
OUT
/
P
D
Thermal Regulation
Note 6
--
0.04
--
%W
T
SD
Thermal Shutdown Die Temperature
--
160
--
C
T
SD
Thermal Shutdown Hysteresis
--
10
--
C
eN
Output Noise
I
L
= I
OUTMAX
--
160
--
V
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
ABSOLUTE MAXIMUM RATINGS*
Input Voltage ................................................................. 7V
Output Voltage ............................. ( 0.3V) to (V
IN
+ 0.3V)
Power Dissipation .................... Internally Limited (Note 7)
Operating Temperature Range ........ 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
Lead Temperature (Soldering, 10 Sec.) ................ +260
C
*Stresses above 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 above
those indicated in the operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for extended periods
may affect device reliability.
TC1054
3
PRELIMINARY INFORMATION
TC1054-01 6/12/97
50mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 0.1mA, C
L
= 3.3
F, SHDN > V
IH
, T
A
= 25
C, unless otherwise noted.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
ERROR Output
V
MIN
Minimum Operating Voltage
1.0
--
--
V
V
OL
Output Logic Low Voltage
1mA Flows to ERROR
--
--
400
mV
V
TH
ERROR Threshold Voltage
See Figure 2
--
0.95 x V
R
--
V
V
HYS
ERROR Positive Hysteresis
Note 8
--
50
--
mV
NOTES: 1. V
R
is the regulator output voltage setting. V
R
= 2.5V, 2.7V, 3.0V, 3.3V, 5.0V.
2. TC V
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 0.1mA 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.
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
, q
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.
8. Hysteresis voltage is referenced by V
R
.
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, ERROR is open circuited and supply current is reduced to 0.05 microamp
(typical).
4
ERROR
Out-of-Regulation Flag. (Open drain output). This output goes low when V
OUT
is out-of-tolerance
by approximately 5%.
5
V
OUT
Regulated voltage output.
PIN DESCRIPTION
(SOT-23A-5)
Symbol
Description
TC1054
50mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
4
PRELIMINARY INFORMATION
TC1054-01 6/12/97
DETAILED DESCRIPTION
The TC1054 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 TC1054 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 and ERROR is open
circuited.
ERROR Open Drain Output
ERROR is driven low whenever V
OUT
falls out of regu-
lation by more than 5% (typical). This condition may be
caused by low input voltage, output current limiting, or
thermal limiting. The ERROR threshold is 5% below rated
V
OUT
regardless of the programmed output voltage value
(e.g. ERROR = V
OL
at 4.75 (typ.) for a 5.0V regulator and
2.85V (typ.) for a 3.0V regulator). ERROR output operation
is shown in Figure 2.
Note that ERROR is active when V
OUT
falls to V
TH
, and
inactive when V
OUT
rises above V
TH
= V
HYS
.
As shown in Figure 1, ERROR can be used as a battery
low flag, or as a processor RESET signal (with the addition
of timing capacitor C2). R1 x C2 should be chosen to
maintain ERROR below V
IH
of the processor RESET input
for at least 200msec to allow time for the system to stabilize.
Pull-up resistor R1 can be tied to V
OUT
, V
IN
or any other
voltage less than (V
IN
= 0.3V).
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 tanta-
lum capacitor 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 tech-
niques.
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
C1
0.2
F
C2
R1
1M
V
+
C2 Requires Only
if ERROR is used as a
Processor RESET Signal
(See Text)
Shutdown Control
(to CMOS Logic or Tie
to V
IN
if unused)
BATTLOW
or RESET
TC1054VCT
V
IN
BATTERY
V
OUT
ERROR
SHDN
GND
V
OUT
1
F
Figure 2. ERROR Output Operation
V
IH
V
OL
ERROR
V
TH
V
OUT
HYSTERESIS (V
HYS
)
TC1054
5
PRELIMINARY INFORMATION
TC1054-01 6/12/97
50mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
In this example, the TC1054 dissipates a maximum of
only 18.5mW; 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.
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 in-
crease the maximum allowable power dissipation limit.
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
). 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 1.05) (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
TC1054
50mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
6
PRELIMINARY INFORMATION
TC1054-01 6/12/97
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
Austin Product Center
9101 Burnet Rd. Suite 214
Austin, TX 78758
TEL: 512-873-7100
FAX: 512-873-8236
TelCom Semiconductor H.K. Ltd.
10 Sam Chuk Street, Ground Floor
San Po Kong, Kowloon
Hong Kong
TEL: 852-2324-0122
FAX: 852-2354-9957
PACKAGE DIMENSIONS
SOT-23A-5*
Dimensions: inches (mm)
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
.071 (1.80)
.059 (1.50)
.122 (3.10)
.098 (2.50)
0.75 (1.90)
REFERENCE
.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)
MARKINGS
SOT-23A-5
&
= part number code + temperature range and voltage
TC1054 (V)
Code
2.5
C1
2.7
C2
3.0
C3
3.3
C4
5.0
C6
represents year and quarter code
represents lot ID number
TC1055
1
PRELIMINARY INFORMATION
TC1055-01 6/5/97
100mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
ORDERING INFORMATION
Output
Junction
Part No.
Voltage **(V) Package
Temp. Range
TC1055-2.5VCT
2.5
SOT-23A-5* 40
C to +125
C
TC1055-2.7VCT
2.7
SOT-23A-5* 40
C to +125
C
TC1055-3.0VCT
3.0
SOT-23A-5* 40
C to +125
C
TC1055-3.3VCT
3.3
SOT-23A-5* 40
C to +125
C
TC1055-5.0VCT
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
GENERAL DESCRIPTION
The TC1055 is a high accuracy (typically
0.5%) CMOS
upgrade for older (bipolar) low dropout regulators. De-
signed specifically for battery-operated systems, the
TC1055'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!).
TC1055 key features include ultra low noise operation,
very low dropout voltage (typically 200mV at full load) and
internal feed-forward compensation for fast response to
step changes in load. An error output (ERROR) is asserted
when the TC1055 is out-of-regulation (due to a low input
voltage or excessive output current). ERROR can be used
as a low battery warning or as a processor RESET signal
(with the addition of an external RC network). Supply current
is reduced to less than 1
A, and both V
OUT
and ERROR
are disabled when the shutdown input is low. The TC1055
incorporates both over-temperature and over-current pro-
tection.
The TC1055 is stable with an output capacitor of only
1
F and has a maximum output current of 100mA. For
higher output current regulators, please see the TC1107,
TC1108 (I
OUT
= 300mA) data sheets.
100mA CMOS LDO WITH SHUTDOWN AND ERROR OUTPUT
TC1055
PIN CONFIGURATION
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
ERROR Output can be Used as a Low Battery
Detector, or Processor Reset Generator
s
Over-Current and Over-Temperature Protection
s
Space-Saving SOT-23A-5 Package
s
Pin Compatible Upgrades for Bipolar Regulators
APPLICATIONS
s
Battery Operated Systems
s
Portable Computers
s
Medical Instruments
s
Instrumentation
s
Cellular/GSMS/PHS Phones
s
Linear Post-Regulators for SMPS
s
Pagers
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices
TYPICAL APPLICATION
TC1055
(SOT-23A-5*)
TOP VIEW
1
3
4
5
2
SHDN
ERROR
GND
V
OUT
V
IN
1
F
Shutdown Control
(from Power Control Logic)
TC1055
V
IN
1
2
3
4
5
V
IN
V
OUT
ERROR
SHDN
GND
1M
V
OUT
ERROR
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
TC1055
100mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
2
PRELIMINARY INFORMATION
TC1055-01 6/5/97
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 0.1mA, C
L
= 3.3
F, SHDN > V
IH
, T
A
= 25
C, unless otherwise noted.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
V
IN
Input Operating Voltage
Note 9
--
--
6.5
V
I
OUTMAX
Maximum Output Current
Note 9
100
--
--
mA
V
OUT
Output Voltage
Notes 1, 9
V
R
2.5%
V
R
0.5%
V
R
+ 2.5%
V
TC V
OUT
V
OUT
Temperature Coefficient
Note 2, 9
--
20
--
ppm/
C
40
V
OUT
/
V
IN
Line Regulation
(V
R
+ 1V) < V
IN
< 6V
--
0.05
--
%
V
OUT
/V
OUT
Load Regulation
I
L
= 0.1mA to I
OUTMAX
--
0.5
--
%
(Note 3)
V
IN
V
OUT
Dropout Voltage
I
L
= 0.1mA
--
20
--
mV
I
L
= 20mA
--
70
I
L
= 50mA
--
100
I
L
= 100mA
--
200
(Note 4)
I
GND
Ground Pin Current
I
L
= I
OUTMAX,
(Note 5, 9)
--
0
--
A
I
IN
Supply Current
SHDN = V
IH
, I
L
= 0
--
50
80
A
I
INSD
Shutdown Supply Current
SHDN = 0V
--
--
0.05
A
R
OUT
Output Resistance during Shutdown
SHDN < V
IL
100 x V
R
160 x V
R
--
k
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
--
160
--
nV/
Hz
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
ABSOLUTE MAXIMUM RATINGS*
Input Voltage ................................................................. 7V
Output Voltage ............................. ( 0.3V) to (V
IN
+ 0.3V)
Power Dissipation .................... Internally Limited (Note 7)
Operating Temperature Range ........ 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 above 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 above
those indicated in the operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for extended periods
may affect device reliability.
TC1055
3
PRELIMINARY INFORMATION
TC1055-01 6/5/97
100mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 0.1
A, C
L
= 3.3
F, SHDN > V
IH
, T
A
= 25
C, unless otherwise noted.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
ERROR Open Drain Output
V
MIN
Minimum Operating Voltage
1.0
--
--
V
V
OL
Output Logic Low Voltage
1mA Flows to ERROR
--
--
400
mV
V
TH
ERROR Threshold Voltage
See Figure 2
--
0.95 x V
R
--
V
V
HYS
ERROR Positive Hysteresis
Note 8
--
50
--
mV
NOTES: 1. V
R
is the regulator output voltage setting. V
R
= 2.5V, 2.7V, 3.0V, 3.3V, 5.0V.
2. TC V
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 0.1mA 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.
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
, q
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.
8. Hysteresis voltage is referenced by V
R
.
9. Boldface type specifications apply for junction temperatures of 40
C to +125
C.
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, ERROR is open circuited and supply current is reduced to 0.05 microamp
(typical).
4
ERROR
Out-of-Regulation Flag. (Open drain output). This output goes low when V
OUT
is out-of-tolerance
by approximately 5%.
5
V
OUT
Regulated voltage output.
PIN DESCRIPTION
(SOT-23A-5)
Symbol
Description
TC1055
100mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
4
PRELIMINARY INFORMATION
TC1055-01 6/5/97
DETAILED DESCRIPTION
The TC1055 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 TC1055 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 and ERROR is open
circuited.
ERROR Open Drain Output
ERROR is driven low whenever V
OUT
falls out of regu-
lation by more than 5% (typical). This condition may be
caused by low input voltage, output current limiting, or
thermal limiting. The ERROR threshold is 5% below rated
V
OUT
regardless of the programmed output voltage value
(e.g. ERROR = V
OL
at 4.75 (typ.) for a 5.0V regulator and
2.85V (typ.) for a 3.0V regulator). ERROR output operation
is shown in Figure 2.
Note that ERROR is active when V
OUT
falls to V
TH
, and
inactive when V
OUT
rises above V
TH
by V
HYS
.
As shown in Figure 1, ERROR can be used as a battery
low flag, or as a processor RESET signal (with the addition
of timing capacitor C2). R1 x C2 should be chosen to
maintain ERROR below V
IH
of the processor RESET input
for at least 200msec to allow time for the system to stabilize.
Pull-up resistor R1 can be tied to V
OUT
, V
IN
or any other
voltage less than (V
IN
+ 0.3V).
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 tanta-
lum capacitor 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 tech-
niques.
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
C1
0.2
F
C2
R1
1M
V
+
C2 Requires Only
if ERROR is used as a
Processor RESET Signal
(See Text)
Shutdown Control
(to CMOS Logic or Tie
to V
IN
if unused)
BATTLOW
or RESET
TC1055VCT
V
IN
BATTERY
V
OUT
ERROR
SHDN
GND
V
OUT
1
F
Figure 2. ERROR Output Operation
V
IH
V
OL
ERROR
V
TH
V
OUT
HYSTERESIS (V
HYS
)
TC1055
5
PRELIMINARY INFORMATION
TC1055-01 6/5/97
100mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
In this example, the TC1055 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 substitut-
ing 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 in-
crease the maximum allowable power dissipation limit.
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
). 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 1.05) (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
TC1055
100mA CMOS LDO WITH SHUTDOWN
AND ERROR OUTPUT
6
PRELIMINARY INFORMATION
TC1055-01 6/5/97
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
Austin Product Center
9101 Burnet Rd. Suite 214
Austin, TX 78758
TEL: 512-873-7100
FAX: 512-873-8236
TelCom Semiconductor H.K. Ltd.
10 Sam Chuk Street, Ground Floor
San Po Kong, Kowloon
Hong Kong
TEL: 852-2324-0122
FAX: 852-2354-9957
PACKAGE DIMENSIONS
SOT-23A-5*
Dimensions: inches (mm)
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
.071 (1.80)
.059 (1.50)
.122 (3.10)
.098 (2.50)
0.75 (1.90)
REFERENCE
.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)
MARKINGS
SOT-23A-5
&
= part number code + temperature range and voltage
TC1055 (V)
Code
2.5
D1
2.7
D2
3.0
D3
3.3
D4
5.0
D6
represents year and quarter code
represents lot ID number
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