MICROCHIP TC1108 Technical data
300mA CMOS LDO
TC1108
Features
• Extremely Low Supply Current (50µA, Typ.)
• Very Low Dropout Voltage
• 300mA Output Current
• High Output VoltageAccuracy
• Standard or Custom Output Voltages
• Over Current and Over Temperature Protection
Applications
• Battery Operated Systems
• PortableComputers
• Medical Instruments
• Instrumentation
• Cellular/GSM/PHSPhones
• Linear Post-Regulators for SMPS
• Pagers
Device Selection Table
Part Number Package
TC1108-xxVDB 3-Pin SOT-223 -40°C to +125°C
NOTE: xx indicates output voltages
Available Output Voltages: 2.5, 2.8, 3.0, 3.3, 5.0.
Otheroutputvoltagesareavailable.Please contactMicrochip
T echnology Inc. for details.
Junction
Temp. Range
General Description
The TC1108 is a fixed output, high accuracy (typically
±0.5%) CMOS low dropout regulator. Total supply
current is typically 50µA at full load (20 to 60 times
lower than in bipolar regulators).
TC1108 key features include ultra low noise operation,
very low dropout voltage (typically 240mV at full load),
and f ast response to step changes in load.
The TC1108 incorporates both over temperature and
over current protection. The TC1108 is stable with an
output capacitor of only 1µF and has a maximum
output current of 300mA. I t is available in a SOT-223
package.
Typical Application
1
V
IN
V
IN
TC1108
2
GND
V
OUT
3
+
C1
1µF
V
OUT
Package Type
SOT-223
TC1108VDB
321
V
GNDV
IN
2002 Microchip TechnologyInc. DS21357B-page 1
OUT
TC1108
1.0 ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings*
Input Voltage .........................................................6.5V
Output Voltage..................(V
– 0.3V) to (VIN+0.3V)
SS
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 affectdevice reliability.
Power Dissipation................Internally Limited (Note 6)
Maximum Voltage on Any Pin ........V
Operating Temperature Range......-40°C < T
+0.3V to -0.3V
IN
<125°C
J
Storage Temperature..........................-65°C to +150°C
TC1108 ELECTRICAL SPECIFICATIONS
Electrical Characteristics: VIN=V
specifications apply for junction temperatures of -40°C to +125°C.
Symbol Parameter Min Typ Max Units Test Conditions
V
IN
I
OUTMAX
V
OUT
/∆TV
∆V
OUT
/∆VINLine Regulation — 0.05 0.35 %(VR+1V)≤ VIN ≤ 6V
∆V
OUT
∆V
OUT/VOUT
V
IN-VOUT
I
DD
InputOperating Voltage 2.7 — 6.0 V Note 7
Maximum Output Current 300 ——mA
Output Voltage —
Temperature Coefficient — 40 —ppm/°CNote 2
OUT
Load Regulation — 0.5 2.0 %IL= 0.1mA to I
DropoutVoltage —
Supply Current — 50 90 µA
PSRR Power Supply Rejection Ratio — 60 — dB F
I
OUTSC
/∆PDThermal Regulation — 0.04 — V/W Note 5
∆V
OUT
Output ShortCircuit Current — 550 650 mA V
eN Output Noise — 260 — nV/√Hz
Note 1: VRis the regulator output voltage setting.
2:
TC V
=(V
OUT
OUTMAX–VOUTMIN
V
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
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
thermal shutdown. Please see Section 4.0 Thermal Considerations for more details.
7: The minimum V
OUT
has to justify the conditions: VIN≥ VR+V
IN
+1V,IL=100µA, CL=3.3µF, TA= 25°C, unless otherwise noted. Boldface type
OUT
V
R
–2.5%
—
—
V
±0.5%
R
240
—
20
80
V
R
—
+2.5%
30
160
480
V Note 1
mV I
=0.1mA
L
I
= 100mA
L
I
= 300mA (Note 4)
L
RE
OUT
F=10kHz,C
R
LOAD
6
)x10
x ∆T
at VIN= 6V for T = 10 msec.
LMAX
, θJA). Exceeding the maximum allowable power dissipation causes the device to initiate
A,TJ
and VIN≥ 2.7V for IL= 0.1mA to I
DROPOUT
OUTMAX
OUTMAX
≤ 1kHz
=0V
OUT
=50Ω
.
(Note 3)
=1µF,
DS21357B-page 2
2002 Microchip TechnologyInc.
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
TC1108
Pin No.
(3-PinSOT-223)
1V
2 GND Groundterminal.
3V
Symbol Description
IN
OUT
Unregulated supply input.
Regulated voltage output.
3.0 DETAILED DESCRIPTION
The TC1108 is a precision, fixed output LDO. Unlike
bipolar regulators, the TC1108’s supply current does
not increase with load current. In addition, V
remains stable and within regulation over the entire
0mA to I
OUTMAX
operating l oad current range, (an
important consideration in RTC and CMOS RAM
battery back-up applications).
Figure 3-1 shows a typical application circuit.
FIGURE 3-1: TYPICAL AP P LICATION
CIRCUIT
V
OUT
3
+
C2
1µF
Battery
1
V
C1
1µF
2
GND
IN
TC1108
+
+
–
V
OUT
OUT
3.1 Output Capacitor
A1µF (min) capacitorfrom V
The output capacitor should have an effective series
resistance greaterthan0.1Ω andlessthan5.0Ω.A1µF
capacitorshould be connected from V
is m ore 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 al uminum
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.
to ground is required.
OUT
to GND if there
IN
2002 Microchip TechnologyInc. DS21357B-page 3
TC1108
4.0 THERMAL CONSIDERATIONS
4.1 Thermal Shutdown
Integrated thermal protection circuitry shuts the
regulator off when die temperature exceeds 150°C.
The regulator remains off until the die temperature
drops to approximately 140°C.
4.2 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:
EQUATION 4-1:
≈ (V
P
D
INMAX–VOUTMIN)ILOADMAX
Where:
= Worst case actual power dissipation
P
D
= Maximum voltage on V
V
INMAX
V
I
LOADMAX
= Minimum regulator output voltage
OUTMIN
= Maximum output (load) current
The maximum allowable power dissipation (Equation
4-2) is a function of t he maximum ambient temperature
(T
), the maximum allowable die temperature
AMAX
(T
) and the thermal resistance from junction-to-air
JMAX
(θ
).
JA
EQUATION 4-2:
P
=(T
DMAX
Where all terms are previously defined.
JMAX–TAMAX
θ
JA
IN
)
Equation 4-1 can be used in conjunction with Equation
4-2 to ensure regulator thermal operation is within
limits. For example:
Given:
V
INMAX
V
OUTMIN
I
LOADMAX
T
JMAX
T
AMAX
θ
JA
= 3.3V + 10%
=2.7V–0.5%
= 275mA
= 125°C
=95°C
=59°C/W
Find: 1. Actual power dissipation
2. Maximum allowable dissipation
Actual power dissipation:
P
≈ (V
D
INMAX–VOUTMIN)ILOADMAX
= [(3.3 x 1.1) – (2.7 x .995)]275 x 10
–3
= 260mW
Maximum allowable power dissipation:
P
DMAX
=(T
JMAX–TAMAX
θ
)
JA
= (125 – 95)
59
= 508mW
In this example, the TC1108 dissipates a maximum of
260mW; below the allowable limit of 508mW. In a
similar manner, Equation 4-1 and Equation 4-2 can be
used to calculate maximum current and/or input
voltage limits. For example, the maximum allowable
V
, is found by sustituting the maximum allowable
IN
power dissipation of 508mW into Equation 4-1, from
which V
INMAX
=4.6V.
Table 4-1 shows various values of θJAfor the TC1108
versus board copper area.
TABLE 4-1: THERMAL RESISTANCE
GUIDELINES FOR TC1108
Copper
Area
(Topside)*
2500 sq mm 2500sq mm 2500 sq mm 45°C/W
1000 sq mm 2500sq mm 2500 sq mm 45°C/W
225 sq mm 2500 sq mm 2500 sq mm 53°C/W
100 sq mm 2500 sq mm 2500 sq mm 59°C/W
1000 sq mm 1000sq mm 1000 sq mm 52°C/W
1000 sq mm 0 sq mm 1000sq mm 55°C/W
Copper
Area
(Backside)
Board
Area
NOTE: *Tab of device attached to topside copper
DS21357B-page 4
Thermal
Resistance
(θ
)
JA
2002 Microchip TechnologyInc.
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