21357C.book

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 2002-2012 Microchip Technology Inc.

DS21357C-page 1

TC1108

Features

• Extremely Low Supply Current (50

A, Typ.)

• Very Low Dropout Voltage

• 300mA Output Current

• High Output Voltage Accuracy

• Standard or Custom Output Voltages

• Over Current and Over Temperature Protection

Applications

• Battery Operated Systems

• Portable Computers

• Medical Instruments

• Instrumentation

• Cellular/GSM/PHS Phones

• Linear Post-Regulators for SMPS

• Pagers

Device Selection Table

NOTE: xx indicates output voltages

Available Output Voltages: 2.5, 2.8, 3.0, 3.3, 5.0.

Other output voltages are available. Please contact Microchip
Technology Inc. for details.

Package Type

General Description

The TC1108 is a fixed output, high accuracy (typically
±0.5%) CMOS low dropout regulator. Total supply
current is typically 50

A 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 fast 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 1

F and has a maximum

output current of 300mA. It is available in a SOT-223
package.

Typical Application

Part Number

Package

Junction

Temp. Range

TC1108-xxVDB

3-Pin SOT-223

-40°C to +125°C

SOT-223

3

2

1

V

OUT

GND

V

IN

TC1108VDB

TC1108

1

2

3

V

IN

V

OUT

C1
1

μF 

GND

V

OUT

V

IN

+

300mA CMOS LDO

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TC1108

DS21357C-page 2

 2002-2012 Microchip Technology Inc.

1.0

ELECTRICAL 
CHARACTERISTICS

Absolute Maximum Ratings*

Input Voltage .........................................................6.5V

Output Voltage.................. (V

SS

 – 0.3V) to (V

IN

 + 0.3V)

Power Dissipation................Internally Limited (Note 6)

Maximum Voltage on Any Pin  ........ V

IN

 +0.3V to -0.3V

Operating Temperature Range...... -40°C < T

J

 < 125°C

Storage Temperature..........................-65°C to +150°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.

TC1108 ELECTRICAL SPECIFICATIONS

Electrical Characteristics: V

IN

 = V

OUT

 + 1V, I

L

 = 100

A, C

L

 = 3.3

F, T

A

 = 25°C, unless otherwise noted. Boldface type 

specifications apply for junction temperatures of -40°C to +125°C.

Symbol

Parameter

Min

Typ

Max

Units

Test Conditions

V

IN

Input Operating Voltage

2.7

6.0

V

Note 7

I

OUT

MAX

Maximum Output Current

300

mA

V

OUT

Output Voltage

V

R

 – 2.5% 

V

R

 ±0.5%

V

R

 + 2.5%

V

Note 1

V

OUT

/

T

V

OUT

 Temperature Coefficient

40

ppm/°C Note 2

V

OUT

/

V

IN

Line Regulation

0.05

0.35

%

(V

R

 + 1V) 

V

IN

6V

V

OUT

/V

OUT

Load Regulation

0.5

2.0

%

I

L

 = 0.1mA to I

OUT

MAX

 (Note 3)

V

IN

-V

OUT

Dropout Voltage



20
80

240

30

160
480

mV

I

L

 = 0.1mA

I

L

 = 100mA

I

L

 = 300mA (Note 4)

I

DD

Supply Current

50

90

A

PSRR

Power Supply Rejection Ratio

60

dB

F

RE 

1kHz

I

OUT

SC

Output Short Circuit Current

550

650

mA

V

OUT

 = 0V

V

OUT

/

P

D

Thermal Regulation

0.04

V/W

Note 5

eN

Output Noise

260

nV/

Hz F = 10kHz, C

OUT

 = 1

F,

R

LOAD

 = 50

Note

1:

V

R

 is the regulator output voltage setting.

2:

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

L

MAX

 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

JA

). Exceeding the maximum allowable power dissipation causes the device to initiate 

thermal shutdown. Please see Section 4.0 Thermal Considerations for more details.

7:

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

OUT

MAX

.

TC V

OUT

 = (V

OUT

MAX

 – V

OUT

MIN

) x 10

6

V

OUT 

T

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 2002-2012 Microchip Technology Inc.

DS21357C-page 3

TC1108

2.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 2-1.

TABLE 2-1:

PIN FUNCTION TABLE

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

OUT

remains stable and within regulation over the entire
0mA to I

OUT

MAX

 operating load 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 APPLICATION
CIRCUIT

3.1

Output Capacitor

A 1

F (min) capacitor from V

OUT

 to ground is required.

The output capacitor should have an effective series
resistance greater than 0.1

 and less than 5.0. 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 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.

Pin No.

(3-Pin SOT-223)

Symbol

Description

1

V

IN

Unregulated supply input.

2

GND

Ground terminal.

3

V

OUT

Regulated voltage output.

C1
1

μF

Battery

TC1108

1

2

3

V

IN

V

OUT

C2
1

μF 

GND

V

OUT

+

+

+

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TC1108

DS21357C-page 4

 2002-2012 Microchip Technology Inc.

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:

The maximum allowable power dissipation (Equation
4-2) is a function of the maximum ambient temperature
(T

A

MAX

), the maximum allowable die temperature

(T

J

MAX

) and the thermal resistance from junction-to-air

(

JA

).

EQUATION 4-2:

Table 4-1 shows various values of 

JA 

for the TC1108

versus board copper area.

TABLE 4-1:

THERMAL RESISTANCE 
GUIDELINES FOR TC1108

NOTE: *Tab of device attached to topside copper

Equation 4-1 can be used in conjunction with Equation
4-2 to ensure regulator thermal operation is within
limits. For example:

Given:

V

IN

MAX

 

= 3.3V + 10%

V

OUT

MIN

= 2.7V – 0.5%

I

LOAD

MAX

 = 275mA

T

J

MAX

= 125°C

 

T

A

MAX

= 95°C

 

JA

= 59°C/W

Find:  1. Actual power dissipation
          2. Maximum allowable dissipation

Actual power dissipation:

P

D

 

 (V

IN

MAX

 – V

OUT

MIN

)I

LOAD

MAX

= [(3.3 x 1.1) – (2.7 x .995)]275 x 10

–3

= 260mW

Maximum allowable power dissipation:

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

IN

, is found by sustituting the maximum allowable

power dissipation of 508mW into Equation 4-1, from
which V

IN

MAX

 = 4.6V.

Copper

Area

(Topside)*

Copper

Area

(Backside)

Board

Area

Thermal

Resistance

(

JA

)

2500 sq mm

2500 sq mm 2500 sq mm

45°C/W

1000 sq mm

2500 sq 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

1000 sq mm 1000 sq mm

52°C/W

1000 sq mm

0 sq mm

1000 sq mm

55°C/W

Where:

P

 (V

IN

MAX

 – V

OUT

MIN

)I

LOAD

MAX

V

IN

MAX

V

OUT

MIN

I

LOAD

MAX

= Worst case actual power dissipation

= Minimum regulator output voltage
= Maximum output (load) current

= Maximum voltage on V

IN

P

D

P

D

MAX

= (T

J

MAX

 – T

A

MAX

)

JA

Where all terms are previously defined.

P

D

MAX

 = (T

J

MAX

 – T

A

MAX

)

JA

= (125 – 95)

59

= 508mW

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 2002-2012 Microchip Technology Inc.

DS21357C-page 5

TC1108

5.0

TYPICAL CHARACTERISTICS

Note:

The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein are
not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.

Output Noise

FREQUENCY (kHz)

NOISE (

μ

V/

HZ)

10.0

1.0

0.01

0.01

1

10

100

1000

0.1

0.0

R

LOAD

 = 50Ω 

C

OUT

 = 1

μF

0.012

0.010

0.008

0.004

0.002

0.000

-0.002

-0.004

0.006

-40

° -20° 0° 20° 40° 60° 80° 100° 120°

TEMPERATURE (

°

C)

 Line Regulation

LINE REGULATION (%)

2.00

1.80

1.60

1.20

1.00

0.80

0.60

0.40

0.20

0.00

1.40

-40

° -20° 0° 20° 40° 60° 80° 100° 120°

TEMPERATURE (

°

C)

Load Regulation

LOAD REGULATION (%)

1 to 300mA

1 to 50mA

1 to 100mA

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00

0

50

100

150

200

250

300

LOAD CURRENT (mA)

DROPOUT VOLTAGE (V)

100.0

90.0

70.0

80.0

50.0

40.0

60.0

-40

° -20° 0° 20° 40° 60° 80° 100° 120°

TEMPERATURE (

°C)

Supply Current

SUPPLY CURRENT (

μ

A)

3.075

3.025

2.925

2.975

-40

° -20° 0° 20° 40° 60° 80° 100° 120°

TEMPERATURE (

°C)

V

OUT

 vs. Temperature

V

OUT

 (V)

125

°C

8

85

°C

C

70

°C

25

°C

0

°C

C

-40

°C

V

IN

 = 4V

I

LOAD

 = 100μA

C

LOAD

 = 3.3

μF

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TC1108

DS21357C-page 6

 2002-2012 Microchip Technology Inc.

6.0

PACKAGING INFORMATION

6.1

Package Marking Information

“1” = part number code

“2” = represents temperature + date code + lot identity
        + subcontractor identity

6.2

Taping Form

    TC1108 (V)

Code

TC1108-2.5VDB

110825

TC1108-2.8VDB

110828

TC1108-3.0VDB

110830

TC1108-3.3VDB

110833

TC1108-5.0VDB

110850

Component Taping Orientation for 3-Pin SOT-223 Devices

 

Package 

Carrier Width (W) 

Pitch (P) 

Part Per Full Reel 

Reel Size

3-Pin SOT-223 

12 mm 

8 mm 

4000 

13 in

Carrier Tape, Number of Components Per Reel and Reel Size

User Direction of Feed

Device

Marking

PIN 1

Standard Reel Component Orientation
for TR Suffix Device
(Mark Right Side Up)

P

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 2002-2012 Microchip Technology Inc.

DS21357C-page 7

TC1108

6.3

Package Dimensions

.264 (6.70)
.248 (6.30)

.122 (3.10)
.114 (2.90)

.287 (7.30)
.264 (6.70)

.146 (3.70)
.130 (3.30)

.091 (2.30) TYP.

.071 

(1.80)

 MAX.

.181 (4.60) TYP.

.036 (0.91) MIN.

.041 (1.04)
.033 (0.84)

PIN 1

.013 (0.33)
.009 (0.24)

.031 (0.80)
.024 (0.60)

.004 (0.10)
.001 (0.02)

10

°

 MAX.

3-Pin SOT-223

Dimensions: inches (mm)

Note:

For the most current package drawings, please see the Microchip Packaging Specification located
at http://www.microchip.com/packaging

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TC1108

DS21357C-page 8

 2002-2012 Microchip Technology Inc.

REVISION HISTORY

Revision C (November 2012)

Added a note to the package outline drawing.

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 2002-2012 Microchip Technology Inc.

DS21357C-page 9

TC1108

SALES AND SUPPORT

Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom-
mended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:

1.

Your local Microchip sales office

2.

The Microchip Worldwide Site (www.microchip.com)

Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.

New Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

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TC1108

DS21357C-page 10

 2002-2012 Microchip Technology Inc.

NOTES:

Maker
Microchip Technology Inc.
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