TC1264
800mA Fixed Output CMOS LDO
FEATURES
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Very Low Dropout Voltage
Guaranteed 800mA Output
High Output Voltage Accuracy
Standard or Custom Output Voltages
Over-Current and Over-Temperature Protection
GENERAL DESCRIPTION
The TC1264 is a fixed output, high accuracy (typically
±0.5%)
CMOS low dropout regulator. Designed specifically
for battery-operated systems, the TC1264’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
!).
TC1264 key features include ultra low noise, very low
dropout voltage (typically 450mV at full load), and fast
response to step changes in load. The TC1264 incorporates
both over-temperature and over-current protection. The
TC1264 is stable with an output capacitor of only 1µF and
has a maximum output current of 800mA. 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
V
OUT
C1
1µF
V
OUT
V
IN
V
IN
Part
Number
TC1264-xxVDB
TC1264-xxVAB
TC1264-xxVEB
Package
3-Pin SOT-223
3-Pin TO-220
3-Pin DDPAK
Junction
Temperature
Range
– 40°C to +125°C
– 40°C to +125°C
– 40°C to +125°C
TC1264
GND
PIN CONFIGURATION
3-Pin TO-220
TAB IS GND
Available Output Voltages:
1.8, 2.5, 3.0, 3.3
xx indicates ouput voltages
3-Pin DDPAK
FRONT VIEW
TAB IS GND
Other output voltages are available. Please contact TelCom
Semiconductor for details.
TC1264
TC1264
1
2
3
1
2
3
GND
GND
V
OUT
FRONT VIEW
V
OUT
TAB IS GND
3
GND
1
2
V
IN
TC1264
TC1264-4 3/28/00
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
800mA Fixed Output CMOS LDO
TC1264
ABSOLUTE MAXIMUM RATINGS*
Input Voltage .............................................................. 6.5V
Output Voltage ........................... (V
SS
– 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
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
R
+ 1.5V
(Note 1)
, 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
Test Conditions
(Note 2)
V
R
> 2.5V
V
R
= 1.8V
Note 3
(V
R
+ 1V) < V
IN
< 6V
I
L
= 0.1mA to I
OUTMAX
(Note 4)
V
R
> 2.5V, I
L
= 100µA
I
L
= 100mA
I
L
= 300mA
I
L
= 500mA
I
L
= 800mA
V
R
= 1.8V, I
L
= 500mA
I
L
= 800mA
(Note 5)
I
L
= 0
F
≤
1kHz
V
OUT
= 0V
Note 6
I
L
= I
OUTMAX
, F = 10kHz
Min
Typ
Max
Units
V
mA
V
ppm/°C
%
%/mA
mV
2.7
—
6.0
800
—
—
V
R
– 2.5%
V
R
±
0.5%
V
R
+ 2.5%
V
R
– 2%
V
R
±
0.5%
V
R
+ 3%
—
40
—
—
0.007
0.35
-0.01
0.002
0
—
20
30
—
50
160
—
150
480
—
260
800
—
450
1300
—
700
1000
—
890
1400
—
—
—
—
—
80
64
1200
0.04
260
130
—
—
—
—
I
DD
PSRR
I
OUTSC
∆V
OUT
/∆P
D
eN
Supply Current
Power Supply Rejection Ratio
Output Short Circuit Current
Thermal Regulation
Output Noise
µA
dB
mA
V/W
nV/√Hz
NOTES:
1. V
R
is the regulator output voltage setting.
2. The minimum V
IN
has to justify the conditions: V
IN
> V
R
+ V
DROPOUT
and V
IN
> 2.7V for I
L
= 0.1mA to I
OUTMAX
.
3. T
C
V
OUT
= (V
OUTMAX
– V
OUTMIN
) x 10
6
V
OUT
x
∆T
4. 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.
5. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at a
1.5V differential.
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
,
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.
TC1264-4
3/28/00
2
800mA Fixed Output CMOS LDO
TC1264
DETAILED DESCRIPTION
The TC1264 is a precision, fixed output LDO. Unlike
bipolar regulators, the TC1264 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
TC1264
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. 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 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.
Table 1 shows various values of
JA
for the TC1264
mounted on a 1/16 inch, 2-layer PCB with 1 oz. copper foil.
Table 1. Thermal Resistance Guidelines for TC1264 in
3-Pin 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 TC1264 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
TC1264-4 3/28/00
3
800mA Fixed Output CMOS LDO
TC1264
Equation 1 can be used in conjunction with Equation 2
to ensure regulator thermal operation is within limits. For
example:
GIVEN:
V
INMAX
= 3.3V
±
10%
V
OUTMIN
= 2.7V
±
0.5%
I
LOADMAX
= 275mA
T
JMAX
= 125°C
T
AMAX
= 95°C
JA
= 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 TC1264 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.
TC1264-4
3/28/00
4
800mA Fixed Output CMOS LDO
TC1264
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
V
OUT =
3V
1mA to 800mA
0.016
0.014
0.012
0.010
0.008
0.006
0.004
0.002
0.000
–40°C
0°C
25°C
70°C
85°C 125°C
0.0
0.01
0.01
1
10
100
1000
NOISE (µV/√/ HZ)
1.0
0.1
TEMPERATURE (°C)
I
DD
vs. Temperature
150
135
120
105
I
DD
(µA)
DROPOUT VOLTAGE (V)
FREQUENCY (KHz)
TEMPERATURE (°C)
3.0V VOUT VS. Temperature
3.030
3.020
3.010
3.000
VOUT (V)
3.0V Dropout Voltage vs. I
LOAD
0.600
0.550
0.500
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
–40°C
85°C
70°C
25°C
125°C
I
LOAD
= 0.1mA
2.990
2.980
2.970
2.960
2.950
2.940
2.930
2.920
–40°C
I
LOAD
= 300mA
I
LOAD
= 500mA
90
75
60
45
30
15
0
–40°C
0°C
25°C
V
OUT =
3V
0°C
I
LOAD
= 800mA
70°C
85°C 125°C
0 100 200 300 400 500 600 700 800
I
LOAD
(mA)
0°C
25°C
70°C
85°C 125°C
TEMPERATURE (°C)
Power Supply Rejection Ratio
–30dB
–35dB
V
OUT
= 3V
R
LOAD
= 50Ω
–40dB V
INAC
= 50mVp-p
–45dB
–50dB
–55dB
–60dB
–65dB
–70dB
–75dB
–80dB
10
100 1K
10K 100K 1M
FREQUENCY (Hz)
C
OUT
= 1µF
TEMPERATURE (°C)
PSRR (dB)
TC1264-4 3/28/00
5
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