TC1262
500mA Fixed Output CMOS LDO
FEATURES
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Very Low Dropout Voltage
Guaranteed 500mA Output
High Output Voltage Accuracy
Standard or Custom Output Voltages
Over-Current and Over-Temperature Protection
GENERAL DESCRIPTION
The TC1262 is a fixed output, high accuracy (typically
±0.5%)
CMOS low dropout regulator. Designed specifically
for battery-operated systems, the TC1262’s CMOS con-
struction eliminates wasted ground current, significantly
extending battery life. Total supply current is typically
80
µA
at full load
(20 to 60 times lower than in bipolar
regulators
).
TC1262 key features include ultra low noise, very low
dropout voltage (typically 350mV at full load), and fast
response to step changes in load. The TC1262 incorporates
both over-temperature and over-current protection. The
TC1262 is stable with an output capacitor of only 1µF and
has a maximum output current of 500mA. It is available in 3-
Pin SOT-223, 3-Pin TO-220, and 3-Pin DDPAK packages.
APPLICATIONS
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Battery-Operated Systems
Portable Computers
Medical Instruments
Instrumentation
Cellular / GSM / PHS Phones
Linear Post-Regulator for SMPS
Pagers
TYPICAL APPLICATION
ORDERING INFORMATION
Part
Number
TC1262-xxVDB
TC1262-xxVAB
TC1262-xxVEB
Package
Junction
Temp. Range
V
IN
V
IN
V
OUT
C1
1µF
V
OUT
TC1262
GND
3-Pin SOT-223 – 40°C to +125°C
3-Pin TO-220
– 40°C to +125°C
3-Pin DDPAK – 40°C to +125°C
PIN CONFIGURATION
3-Pin TO-220
TAB IS GND
Available Output Voltages:
2.5, 2.8, 3.0, 3.3, 5.0
xx indicates output voltages
3-Pin DDPAK
FRONT VIEW
TAB IS GND
Other output voltages are available. Please contact TelCom
Semiconductor for details.
TC1262
TC1262
1
2
3
1
2
3
GND
GND
V
OUT
FRONT VIEW
V
OUT
TAB IS GND
3
GND
1
2
V
IN
TC1262
TC1262-2 1/28/00
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices.
V
OUT
V
IN
V
IN
3-Pin SOT-223
500mA Fixed Output CMOS LDO
TC1262
ABSOLUTE MAXIMUM RATINGS*
Input Voltage .............................................................. 6.5V
Output Voltage ........................... (V
SS
– 0.3) to (V
IN
+ 0.3)
Power Dissipation .................... Internally Limited (Note 6)
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
Lead Temperature (Soldering, 10 Sec.) ................ +260°C
*Absolute Maximum Ratings indicate device operation limits beyond dam-
age may occur. Device operation beyond the limits listed in Electrical
Characteristics is not recommended.
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 100µA, C
L
= 3.3µF, T
A
= 25°C, unless otherwise specified.
BOLDFACE
type specifications apply for junction temperatures of – 40°C to
+125°C.
Symbol
V
IN
I
OUTMAX
V
OUT
∆V
OUT
/∆T
∆V
OUT
/∆V
IN
∆V
OUT
/V
OUT
V
IN
– V
OUT
Parameter
Input Operating Voltage
Maximum Output Current
Output Voltage
V
OUT
Temperature Coefficient
Line Regulation
Load Regulation
Dropout Voltage (Note 4)
Test Conditions
Min
Typ
Max
Units
V
mA
V
ppm/°C
%
%/mA
mV
Note 1
Note 2
(V
R
+ 1V) < V
IN
< 6V
I
L
= 0.1mA to I
OUTMAX
(Note 3)
I
L
= 100µA
I
L
= 100mA
I
L
= 300mA
I
L
= 500mA
I
L
= 0
F
RE
≤
1KHz
V
OUT
= 0V
Note 5
I
L
= I
OUTMAX
I
DD
PSRR
I
OUTSC
∆V
OUT
/∆P
D
eN
Supply Current
Power Supply Rejection Ratio
Output Short Circuit Current
Thermal Regulation
Output Noise
—
—
6.0
500
—
—
—
V
R
±
0.5%
—
V
R
– 2.5%
—
V
R
+ 2.5%
—
40
—
—
.003
0.35
—
0.002
0.01
—
20
30
—
60
160
—
200
480
—
350
800
—
80
130
—
64
—
—
1200
—
—
0.04
—
—
260
—
µA
dB
mA
V/W
nV/√Hz
NOTES:
1. V
R
is the regulator output voltage setting.
2. T
C
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 measured at a 1V
differential.
5. 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 = 10 msec.
6. 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
,
θ
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.
TC1262-2
1/28/00
2
500mA Fixed Output CMOS LDO
TC1262
DETAILED DESCRIPTION
The TC1262 is a precision, fixed output LDO. Unlike
bipolar regulators, the TC1262 supply current does not
increase with load current. In addition, V
OUT
remains stable
and within regulation at very low load currents (an important
consideration in RTC and CMOS RAM battery backup
applications). Figure 1 shows a typical application circuit.
Where:
P
D
≈
(V
INMAX
– V
OUTMIN
)I
LOADMAX
P
D
=
V
INMAX
=
V
OUTMIN
=
I
LOADMAX
=
worst case actual power dissipation
maximum voltage on V
IN
minimum regulator output voltage
maximum output (load) current
Equation 1.
V
IN
C1
1µF
Battery
V
OUT
C2
1µF
V
OUT
TC1262
GND
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
).
P
DMAX
=
(T
JMAX
– T
AMAX
)
JA
Where all terms are previously defined.
Figure 1: Typical Application Circuit
Equation 2.
Output Capacitor
A 1µF (min) capacitor from V
OUT
to ground is required.
The output capacitor should have an effective series resis-
tance of 5Ω or less, and a resonant frequency above 1 MHz.
A 1µF 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 capacitor types
can be used. (Since many aluminum electrolytic capacitors
freeze at approximately –30°C, solid tantalums are recom-
mended for applications operating below –25°C.) When
operating from sources other than batteries, supply-noise
rejection and transient response can be improved by in-
creasing the value of the input and output capacitors and
employing passive filtering techniques.
Table 1 shows various values of
JA
for the TC1262
mounted on a 1/16 inch, 2-layer PCB with 1 oz. copper foil.
Table 1. Thermal Resistance Guidelines for TC1262 in
SOT-223 Package
Copper
Area
(Topside)*
2500 sq mm
1000 sq mm
225 sq mm
100 sq mm
1000 sq mm
1000 sq mm
Copper
Area
(Backside)
2500 sq mm
2500 sq mm
2500 sq mm
2500 sq mm
1000 sq mm
0 sq mm
Board
Area
2500 sq mm
2500 sq mm
2500 sq mm
2500 sq mm
1000 sq mm
1000 sq mm
Thermal
Resistance
(
JA
)
45°C/W
45°C/W
53°C/W
59°C/W
52°C/W
55°C/W
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:
NOTES:
*Tab of device attached to topside copper
Table 2. Thermal Resistance Guidelines for TC1262 in
3-Pin DDPAK/TO-220 Package
Copper
Area
(Topside)*
2500 sq mm
1000 sq mm
125 sq mm
Copper
Area
(Backside)
2500 sq mm
2500 sq mm
2500 sq mm
Board
Area
2500 sq mm
2500 sq mm
2500 sq mm
Thermal
Resistance
(
JA
)
25°C/W
27°C/W
35°C/W
NOTES:
*Tab of device attached to topside copper
Equation 1 can be used in conjunction with Equation 2
to ensure regulator thermal operation is within limits. For
example:
3
TC1262-2
1/28/00
500mA Fixed Output CMOS LDO
TC1262
GIVEN:
V
INMAX
V
OUTMIN
I
LOAD
T
AMAX
JA
=
=
=
=
=
3.3V
±
10%
2.7V
±
0.5%
275mA
95°C
59°C/W (SOT-223)
FIND: 1. Actual power dissipation
2. Maximum allowable dissipation
Actual power dissipation:
P
D
≈
(V
INMAX
– V
OUTMIN
)I
LOADMAX
= [(3.3 x 1.1) – (2.7 x .995)]275 x 10
-3
= 260mW
Maximum allowable power dissipation:
(T
JMAX
– T
AMAX
)
P
D
MAX
=
JA
=
=
(125 – 95)
59
508mW
In this example, the TC1262 dissipates a maximum of
only 260mW; far below the allowable limit of 508mW. 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 508mW
into Equation 1, from which V
INMAX
= 4.6V.
TC1262-2
1/28/00
4
500mA Fixed Output CMOS LDO
TC1262
TYPICAL CHARACTERISTICS
Line Regulation vs. Temperature
0.020
0.018
LINE REGULATION (%)
Output Noise vs. Frequency
10.0
0.0100
R
LOAD
= 50µΩ
C
OUT
= 1µF
LOAD REGULATION %/mA
Load Regulation vs. Temperature
0.0090
0.0080
0.0070
0.0060
0.0050
0.0040
0.0030
0.0020
0.0010
0.0100
–40°C
0°C
25°C
70°C
85°C
125°C
5V
2.5V
1mA to 500mA
0.016
0.014
0.012
0.010
0.008
0.006
0.004
0.002
0.000
–40°C
0.0
0°C
25°C
70°C
85°C 125°C
0.01
0.01
1
10
100
1000
TEMPERATURE (°C)
I
DD
vs. Temperature
150
135
DROPOUT VOLTAGE (V)
NOISE (µV/√/ HZ)
1.0
0.1
1mA to 500mA
FREQUENCY (KHz)
TEMPERATURE (°C)
5.0V Dropout Voltage vs. I
LOAD
0.50
125°C
2.5V Dropout Voltage vs. I
LOAD
0.50
125°C
DROPOUT VOLTAGE (V)
120
105
I
DD
(µA)
0.40
25°C
85°C
70°C
0.40
85°C
0.30
70°C
25°C
0.20
0°C
0.10
–40°C
90
75
60
45
30
15
0
–40°C
2.5V
5V
0.30
0.20
–40°C
0.10
0°C
0.00
0°C
25°C
70°C
85°C 125°C
0
100
200
300
400
500
TEMPERATURE (°C)
2.5V VOUT VS. Temperature
I
LOAD
(mA)
5.0V VOUT VS. Temperature
5.20
5.10
5.00
4.90
4.80
4.70
4.60
4.50
4.40
4.30
4.20
4.10
4.00
–40°C
0.00
0
100
200
300
400
500
I
LOAD
(mA)
Power Supply Rejection Ratio
–30dB
I
L
= 0.1mA
–35dB
V
OUT
= 3V
R
LOAD
= 50Ω
–40dB V
INAC
= 50mVp-p
–45dB
I
L
= 300mA
I
L
= 500mA
PSRR (dB)
2.70
2.50
2.30
VOUT (V)
VOUT (V)
I
L
= 0.1mA
2.10
1.90
1.70
I
L
= 300mA
I
L
= 500mA
–50dB
–55dB
–60dB
–65dB
–70dB
–75dB
C
OUT
= 1µF
1.50
–40°C
0°C
25°C
70°C
85°C
125°C
0°C
25°C
70°C
85°C
125°C
–80dB
10
100
1K
10K
100K 1M
FREQUENCY (KHz)
TEMPERATURE (°C)
TEMPERATURE (°C)
TC1262-2
1/28/00
5
51mcu
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