TELCOM TC1014

50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1014
TC1014
50mA CMOS LDO WITH SHUTDOWN AND REFERENCE BYPASS
FEATURES
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 systems, the TC1014’s CMOS construction eliminates wasted
ground current, significantly extending battery life. Total
supply current is typically 50µA 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 compensation for fast response to step changes in load. Supply
current is reduced to less than 1µA when the shutdown input
is low. The TC1014 also incorporates both over-temperature and over-current protection.
The TC1014 is stable with an output capacitor of only
1µF and has a maximum output current of 100mA. For
higher output versions, please see the TC1107, TC1108,
TC1173 (IOUT = 300mA) data sheets.
■
■
■
Zero Ground Current for Longer Battery Life!
Very Low Dropout Voltage
Guaranteed 50mA Output
High Output Voltage Accuracy
Standard or Custom Output Voltages
Power-Saving Shutdown Mode
Reference Bypass Input for Ultra Low-Noise
Operation
Over-Current and Over-Temperature Protection
Space-Saving SOT-23A-5 Package
Pin Compatible Upgrade for MIC5205 and
NSC2980
APPLICATIONS
■
■
■
■
■
■
■
Battery Operated Systems
Portable Computers
Medical Instruments
Instrumentation
Cellular / GSM / PHS Phones
Linear Post-Regulator for SMPS
Pagers
ORDERING INFORMATION
Part No.
TYPICAL APPLICATION
VIN
1
VOUT
VIN
5
VOUT
1µF
2
3
GND
SHDN
Output
Voltage **(V) Package
Junction
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
PIN CONFIGURATION
TC1014
Bypass
4
VOUT
Bypass
5
4
470pF
Reference
Bypass Cap
(Optional)
TC1014
(SOT-23A-5*)
1
Shutdown Control
(from Power Control Logic)
VIN
2
3
TOP VIEW
GND SHDN
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
TC1014-01-6/5/97
TelCom Semiconductor reserves the right to make changes in the circuitry and1specifications to its devices.
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1014
ABSOLUTE MAXIMUM RATINGS*
*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.
Input Voltage .................................................................7V
Output Voltage .................................. (– 0.3) to (VIN + 0.3)
Power Dissipation .................... Internally Limited (Note 7)
Operating Temperature .................... – 40°C < TJ < 125°C
Storage Temperature ............................ – 65°C to +150°C
Maximum Voltage On Any Pin .......... VIN + 0.3V to – 0.3V
ELECTRICAL CHARACTERISTICS: VIN = VOUT + 1V, IL = 100µA, CL = 3.3µF, SHDN > VIH, TA = 25°C, unless otherwise noted.
Boldface type specifications apply for junction temperatures of – 40°C to +125°C.
Symbol
Parameter
VIN
IOUTMAX
VOUT
TCVOUT
Input Operating Voltage
Maximum Output Current
Output Voltage
VOUT Temperature Coefficient
∆VOUT/∆VIN
∆VOUT/VOUT
Line Regulation
Load Regulation
VIN – VOUT
Dropout Voltage (Note 4)
IGND
IIN
IINSD
PSRR
IOUTSC
∆VOUT/∆PD
eN
Ground Pin Current
Supply Current
Shutdown Supply Current
Power Supply Rejection Ratio
Output Short Circuit Current
Thermal Regulation
Output Noise
Test Conditions
Note 1
Note 2
Min
Typ
Max
Units
—
50
VR – 2.5%
—
—
VR ±0.5%
20
40
0.01
0.5
6.5
—
VR + 2.5%
—
V
mA
V
ppm/°C
—
—
%
%
—
5
65
95
—
mV
(VR + 1V) < VIN < 6V
IL = 1.0mA to IOUTMAX
(Note 3)
IL = 100µA
IL = 20mA
IL = 50mA
(Note 4)
IL = IOUTMAX, (Note 5)
SHDN = VIH, IL = 0
SHDN = 0V
FRE ≤ 1kHz
VOUT = 0V
Note 6
IL = IOUTMAX
470pF from Bypass to GND
—
—
—
—
—
—
—
—
—
—
50
—
64
200
0.04
260
0
—
0.05
—
400
—
—
µA
µA
µA
dB
mA
%/W
nV/√Hz
VIN = 2.5V to 6.5V
VIN = 2.5V to 6.5V
45
—
—
—
—
15
%VIN
%VIN
SHDN Input
VIH
VIL
SHDN Input High Threshold
SHDN Input Low Threshold
NOTES: 1. VR is the regulator output voltage setting. VR = 2.5V, 2.7V, 3.0V, 3.3V, 5.0V.
2. TCVOUT = (VOUTMAX – VOUTMIN) x 10 6
VOUT 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. IIN = ISUPPLY + IGND + ILOAD).
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 ILMAX at VIN = 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. TA, TJ, θJA). 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.
.
TC1014-01-6/5/97
2
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1014
PIN DESCRIPTION
Pin No.
(SOT-23A-5)
Symbol
1
2
3
VIN
GND
SHDN
4
5
Bypass
VOUT
Description
Unregulated supply input.
Ground terminal.
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).
Reference bypass input. Connecting a 470pF to this input further reduces output noise.
Regulated voltage 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.
DETAILED DESCRIPTION
The TC1014 is a precision fixed output voltage regulator. (If an adjustable version is desired, please see the
TC1070 or TC1071 data sheets.) Unlike the bipolar regulators, the TC1014 supply current does not increase with load
current. In addition, VOUT remains stable and within regulation 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 regulator is enabled any time the shutdown input (SHDN) is at or
above VIH, and shutdown (disabled) when SHDN is at or
below VIL. 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 0.05µA
(typical) and VOUT falls to zero volts.
1µF
A 1µF (min) capacitor from VOUT to ground is recommended. The output capacitor should have an effective
series resistance of 5Ω or less, and a resonant frequency
above 1MHz. A 1µF capacitor should be connected from VIN
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 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, supplynoise rejection and transient response can be improved by
increasing the value of the input and output capacitors and
employing passive filtering techniques.
VOUT
VOUT
VIN
Output Capacitor
1µF
Thermal Considerations
BATTERY
Thermal Shutdown
Integrated thermal protection circuitry shuts the regulator off when die temperature exceeds 160°C. The regulator
remains off until the die temperature drops to approximately
150°C.
GND
TC1014
SHDN
Bypass
470pF
Reference
Bypass Cap
(Optional)
Power Dissipation
The amount of power the regulator dissipates is primarily a function of input and output voltage, and output current.
The following equation is used to calculate worst case
actual power dissipation:
Shutdown Control
(to CMOS Logic or Tie to VIN if Unused)
Figure 1. Typical Application Circuit
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
TC1014-01-6/5/97
3
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1014
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 VIN is found by sustituting
the maximum allowable power dissipation of 318mW into
Equation 1, from which VINMAX = 5.9V.
PD ≈ (VINMAX – VOUTMIN)ILOADMAX
Where:
PD
VINMAX
VOUTMIN
ILOADMAX
= Worst case actual power dissipation
= Maximum voltage on VIN
= Minimum regulator output voltage
= Maximum output (load) current
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 θJA and, therefore,
increase the maximum allowable power dissipation limit.
Equation 1.
The maximum allowable power dissipation (Equation 2)
is a function of the maximum ambient temperature (TAMAX),
the maximum allowable die temperature (125°C) and the
thermal resistance from junction-to-air (θ JA ). The
SOT-23A-5 package has a θJA of approximately 220°C/Watt
when mounted on a single layer FR4 dielectric copper clad
PC board.
PD MAX = (TJMAX – TJMAX)
θJA
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:
VINMAX = 3.0V ±5%
VOUTMIN = 2.7V ±0.5V
ILOAD = 40mA
TAMAX = 55°C
Find:
1. Actual power dissipation
2. Maximum allowable dissipation
Actual power dissipation:
PD ≈ (VINMAX – VOUTMIN)ILOADMAX
= [(3.0 x 1.1) – (2.7 x .995)]40 x 10–3
= 18.5mW
Maximum allowable power dissipation:
PDMAX = (TJMAX – TAMAX)
θJA
= (125 – 55)
220
= 318mW
TC1014-01-6/5/97
4
50mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1014
a & b = part number code + temperature range and voltage
MARKING
TC1014 (V)
2.5
2.7
3.0
3.3
5.0
SOT-23A-5
Code
A1
A2
A3
A5
A7
c represents year and quarter code
d represents lot ID number
PACKAGE DIMENSIONS
SOT-23A-5*
.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)
.010 (0.25)
.004 (0.09)
10° MAX.
.006 (0.15)
.000 (0.00)
.022 (0.55)
.008 (0.20)
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
Dimensions: inches (mm)
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: [email protected]
TC1014-01-6/5/97
TelCom Semiconductor
Austin Product Center
9101 Burnet Rd. Suite 214
Austin, TX 78758
TEL: 512-873-7100
FAX: 512-873-8236
5
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
Printed in the U.S.A.
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1015
TC1015
100mA CMOS LDO WITH SHUTDOWN AND REFERENCE BYPASS
FEATURES
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 systems, the TC1015’s CMOS construction eliminates wasted
ground current, significantly extending battery life. Total
supply current is typically 50µA 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 (typically 200mV at full load) and internal feed-forward compensation for fast response to step changes in load. Supply
current is reduced to 0.05µA and VOUT 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
1µF and has a maximum output current of 100mA. For
higher output versions, please see the TC1107, TC1108,
TC1173 (IOUT = 300mA) data sheets.
■
■
■
Zero Ground Current for Longer Battery Life!
Very Low Dropout Voltage
Guaranteed 100mA Output
High Output Voltage Accuracy
Standard or Custom Output Voltages
Power-Saving Shutdown Mode
Reference Bypass Input for Ultra Low-Noise
Operation
Over-Current and Over-Temperature Protection
Space-Saving SOT-23A-5 Package
Pin Compatible Upgrade for MIC5205 and
NSC2980
APPLICATIONS
■
■
■
■
■
■
■
Battery Operated Systems
Portable Computers
Medical Instruments
Instrumentation
Cellular / GSM / PHS Phones
Linear Post-Regulator for SMPS
Pagers
ORDERING INFORMATION
Part No.
TYPICAL APPLICATION
VIN
1
VOUT
VIN
5
VOUT
1µF
2
GND
SHDN
Junction
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
PIN CONFIGURATION
TC1015
3
Output
Voltage **(V) Package
Bypass
4
VOUT
Bypass
5
4
470pF
Reference
Bypass Cap
(Optional)
TC1015
(SOT-23A-5*)
1
Shutdown Control
(from Power Control Logic)
VIN
2
3
TOP VIEW
GND SHDN
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
TC1015-01-6/5/97
TelCom Semiconductor reserves the right to make changes in the circuitry and1specifications to its devices.
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1015
ABSOLUTE MAXIMUM RATINGS*
*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.
Input Voltage .................................................................7V
Output Voltage .................................. (– 0.3) to (VIN + 0.3)
Power Dissipation .................... Internally Limited (Note 7)
Operating Temperature .................... – 40°C < TJ < 125°C
Storage Temperature ............................ – 65°C to +150°C
Maximum Voltage On Any Pin .......... VIN + 0.3V to – 0.3V
ELECTRICAL CHARACTERISTICS: VIN = VOUT + 1V, IL = 100µA, CL = 3.3µF, SHDN > VIH, TA = 25°C, unless otherwise noted.
Boldface type specifications apply for junction temperatures of – 40°C to +125°C.
Symbol
Parameter
VIN
IOUTMAX
VOUT
TCVOUT
Input Operating Voltage
Maximum Output Current
Output Voltage
VOUT Temperature Coefficient
∆VOUT/∆VIN
∆VOUT/VOUT
Line Regulation
Load Regulation
VIN – VOUT
Dropout Voltage (Note 4)
IGND
IIN
IINSD
PSRR
IOUTSC
∆VOUT/∆PD
eN
Ground Pin Current
Supply Current
Shutdown Supply Current
Power Supply Rejection Ratio
Output Short Circuit Current
Thermal Regulation
Output Noise
Test Conditions
Note 1
Note 2
Min
Typ
Max
Units
—
100
VR – 2.5%
—
—
VR ±0.5%
20
40
0.01
0.5
6.5
—
VR + 2.5%
—
V
mA
V
ppm/°C
—
—
%
%
—
20
70
93
112
—
mV
(VR + 1V) < VIN < 6V
IL = 1.0mA to IOUTMAX
(Note 3)
IL = 0.1mA
IL = 20mA
IL = 50mA
IL =100mA
(Note 4)
IL = IOUTMAX, (Note 5)
SHDN = VIH, IL = 0
SHDN = 0V
FRE ≤ 1kHz
VOUT = 0V
Note 6
IL = IOUTMAX
470pF from Bypass to GND
—
—
—
—
—
—
—
—
—
—
50
—
64
300
0.04
260
0
—
0.05
—
500
—
—
µA
µA
µA
dB
mA
%/W
nV/√Hz
VIN = 2.5V to 6.5V
VIN = 2.5V to 6.5V
45
—
—
—
—
15
%VIN
%VIN
SHDN Input
VIH
VIL
SHDN Input High Threshold
SHDN Input Low Threshold
NOTES: 1. VR is the regulator output voltage setting. VR = 2.5V, 2.7V, 3.0V, 3.3V, 5.0V.
2. TCVOUT = (VOUTMAX – VOUTMIN) x 10 6
VOUT 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. IIN = ISUPPLY + IGND + ILOAD).
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 ILMAX at VIN = 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. TA, TJ, θJA). 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.
.
TC1015-01-6/5/97
2
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1015
PIN DESCRIPTION
Pin No.
(SOT-23A-5)
Symbol
1
2
3
VIN
GND
SHDN
4
5
Bypass
VOUT
Description
Unregulated supply input.
Ground terminal.
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).
Reference bypass input. Connecting a 470pF to this input further reduces output noise.
Regulated voltage 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.
DETAILED DESCRIPTION
The TC1015 is a precision fixed output voltage regulator. (If an adjustable version is desired, please see the
TC1070 or TC1071 data sheets.) Unlike the bipolar regulators, the TC1015 supply current does not increase with load
current. In addition, VOUT remains stable and within regulation 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 regulator is enabled any time the shutdown input (SHDN) is at or
above VIH, and shutdown (disabled) when SHDN is at or
below VIL. 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 0.05µA
(typical) and VOUT falls to zero volts.
1µF
A 1µF (min) capacitor from VOUT to ground is recommended. The output capacitor should have an effective
series resistance of 5Ω or less, and a resonant frequency
above 1MHz. A 1µF capacitor should be connected from VIN
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 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, supplynoise rejection and transient response can be improved by
increasing the value of the input and output capacitors and
employing passive filtering techniques.
VOUT
VOUT
VIN
Output Capacitor
1µF
Thermal Considerations
BATTERY
GND
Thermal Shutdown
Integrated thermal protection circuitry shuts the regulator off when die temperature exceeds 160°C. The regulator
remains off until the die temperature drops to approximately
150°C.
TC1015
SHDN
Bypass
470pF
Reference
Bypass Cap
(Optional)
Power Dissipation
The amount of power the regulator dissipates is primarily a function of input and output voltage, and output current.
The following equation is used to calculate worst case
actual power dissipation:
Shutdown Control
(to CMOS Logic or Tie to VIN if Unused)
Figure 1. Typical Application Circuit
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
TC1015-01-6/5/97
3
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1015
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 VIN is found by sustituting
the maximum allowable power dissipation of 318mW into
Equation 1, from which VINMAX = 5.9V.
PD ≈ (VINMAX – VOUTMIN)ILOADMAX
Where:
PD
VINMAX
VOUTMIN
ILOADMAX
= Worst case actual power dissipation
= Maximum voltage on VIN
= Minimum regulator output voltage
= Maximum output (load) current
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 θJA and, therefore,
increase the maximum allowable power dissipation limit.
Equation 1.
The maximum allowable power dissipation (Equation 2)
is a function of the maximum ambient temperature (TAMAX),
the maximum allowable die temperature (125°C) and the
thermal resistance from junction-to-air (θ JA ). The
SOT-23A-5 package has a θJA of approximately 220°C/Watt
when mounted on a single layer FR4 dielectric copper clad
PC board.
PD MAX = (TJMAX – TJMAX)
θJA
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:
VINMAX = 3.0V ±10%
VOUTMIN = 2.7V ±0.5V
ILOAD = 98mA
TAMAX = 55°C
Find:
1. Actual power dissipation
2. Maximum allowable dissipation
Actual power dissipation:
PD ≈ (VINMAX – VOUTMIN)ILOADMAX
= [(3.0 x 1.1) – (2.7 x .995)]98 x 10–3
= 60mW
Maximum allowable power dissipation:
PDMAX = (TJMAX – TAMAX)
θJA
= (125 – 55)
220
= 318mW
TC1015-01-6/5/97
4
100mA CMOS LDO WITH SHUTDOWN
AND REFERENCE BYPASS
PRELIMINARY INFORMATION
TC1015
a & b = part number code + temperature range and voltage
MARKING
TC1015 (V)
2.5
2.7
3.0
3.3
5.0
SOT-23A-5
Code
B1
B2
B3
B5
B7
c represents year and quarter code
d represents lot ID number
PACKAGE DIMENSIONS
SOT-23A-5*
.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)
.010 (0.25)
.004 (0.09)
10° MAX.
.006 (0.15)
.000 (0.00)
.022 (0.55)
.008 (0.20)
Dimensions: inches (mm)
NOTE: *SOT-23A-5 is equivalent to the EIAJ (SC-74A)
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: [email protected]
TC1015-01-6/5/97
TelCom Semiconductor
Austin Product Center
9101 Burnet Rd. Suite 214
Austin, TX 78758
TEL: 512-873-7100
FAX: 512-873-8236
5
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
Printed in the U.S.A.