Linear Technology LTC1261L Datasheet

FEATURES

■

Regulated Negative Voltage from a
Single Positive Supply

■

REG Pin Indicates Output is in Regulation

■

Adjustable or Fixed Output Voltages

■

Output Regulation: ±3.5%

■

Supply Current: 650µA Typ

■

Shutdown Mode Drops Supply Current to 5µA

■

Up to 20mA Output Current

■

Requires Only Three or Four External Capacitors

■

Available in MS8 and SO-8 Packages

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APPLICATIO S

■

GaAs FET Bias Generators

■

Negative Supply Generators

■

Battery-Powered Systems

■

Single Supply Applications

LTC1261L

Switched Capacitor

Regulated Voltage Inverter

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DESCRIPTIO

The LTC®1261L is a switched-capacitor voltage inverter
designed to provide a regulated negative voltage from a
single positive supply. The LTC1261L operates from a
single 2.7V to 5.25V supply and provides an adjustable
output voltage from –1.23V to –5V. The LTC1261L-4/
LTC1261L-4.5 needs a single 4.5V to 5.25V supply and
provides a fixed output voltage of –4V to – 4.5V respec­tively. Three external capacitors are required: a 0.1µF
flying capacitor and an input and output bypass capaci­tors. An optional compensation capacitor at ADJ (COMP)
can be used to reduce the output voltage ripple.

Each version of the LTC1261L will supply up to 20mA
output current with guaranteed output regulation of ±3.5%.
The LTC1261L includes an open-drain REG output that
pulls low when the output is within 5% of the set value.
Quiescent current is typically 650µA when operating and
5µA in shutdown.

TYPICAL APPLICATION

–4V Generator with Power Valid

5V

C1

1µF

0.1µF

1

V

CC

2

+

C2

C1

3

C1

4

GND

LTC1261L-4

–

SHDN

REG

OUT

COMP

8

7

6

5

The LTC1261L is available in 8-pin MSOP and SO pack­ages.

, LTC and LT are registered trademarks of Linear Technology Corporation.

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Waveforms for –4V Generator with Power Valid

0V

5V

10k

POWER VALID

V

= –4V

OUT

AT 10mA

C4

3.3µF

C3*
100pF

+

*OPTIONAL

1261L TA01

OUT

SHDN

POWER VALID

–4V

5V

0V

5V

0V

0.1ms/DIV

1261L TAO2

1

LTC1261L

A

W

O

LUTEXI TIS

S

A

WUW

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ARB

G

(Note 1)

Supply Voltage (Note 2) ........................................ 5.5V

Output Voltage (Note 3)........................... 0.3V to –5.3V

Total Voltage, VCC to V

(Note 2) ..................... 10.8V

OUT

SHDN Pin .................................. –0.3V to (VCC + 0.3V)

REG Pin ..................................................... –0.3V to 6V

ADJ Pin........................... (V

– 0.3V) to (VCC + 0.3V)

OUT

WU

/

PACKAGE

V

1

CC

+

2

C1

–

3

C1

4

GND

8-LEAD PLASTIC MSOP

T

JMAX

O

TOP VIEW

MS8 PACKAGE

= 150°C, θ

JA

RDER I FOR ATIO

ORDER PART

NUMBER

8

SHDN

7

REG

6

OUT

5

ADJ (COMP)

= 200°C/W

LTC1261LCMS8
LTC1261LCMS8-4
LTC1261LCMS8-4.5

MS8 PART MARKING

LTFM
LTFN
LTFP

Output Short-Circuit Duration......................... Indefinite

Commercial Temperature Range ................ 0°C to 70°C

Extended Commercial Operating

Temperature Range (Note 4) ................. – 40°C to 85°C

Storage Temperature Range ................ –65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

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ORDER PART

NUMBER

LTC1261LCS8
LTC1261LCS8-4
LTC1261LCS8-4.5

S8 PART MARKING

1261L
1261L4
261L45

V

1

CC

+

C1

2

–

C1

3

GND

4

8-LEAD PLASTIC SO

T

= 150°C, θ

JMAX

TOP VIEW

S8 PACKAGE

JA

8

7

6

5

= 135°C/W

SHDN
REG
OUT
ADJ (COMP)

Consult factory for Industrial or Military grade parts or additional fixed voltage parts.

LECTRICAL C CHARA TERIST

E

temperature range, otherwise specifications are at TA = 25°C, C1 = 0.1µF, C

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

V
I

f
V
I

I
V
V
I
t

CC

REF

CC

OSC

OL

REG

ADJ

IH

IL

IN

ON

Supply Voltage
(LTC1261LCMS8/LTC1261LCS8)
(LTC1261LCMS8-4/LTC1261LCS8-4) (Note 5)
(LTC1261LCMS8-4.5/LTC1261LCS8-4.5) (Note 5)

Reference Voltage 1.23 V
Supply Current VCC = 5.25V, No Load, SHDN Floating ● 650 1500 µA

V

CC

Internal Oscillator Frequency VCC = 5V, V
REG Output Low Voltage I
REG Sink Current V

Adjust Pin Current V
SHDN Input High Voltage VCC = 5V ● 2V
SHDN Input Low Voltage VCC = 5V ● 0.8 V
SHDN Input Current V
Turn-On Time VCC = 5V, I

REG

REG

V

REG

ADJ

SHDN

V

CC

V

CC

VCC = 5V, I

The ● denotes the specifications which apply over the full operating

ICS

= 3.3µF unless otherwise noted. (Notes 2, 4)

OUT

● 2.7 5.25 V

● 4.35 5.25 V

● 4.75 5.25 V

= 5.25V, No Load, V

= –4V 650 kHz

OUT

= 1mA, VCC = 5V, V

= 0.8V, VCC = 3.3V ● 48 mA
= 0.8V, VCC = 5V ● 512 mA

= 1.23V ● ±0.01 ±1 µA

= V

CC

= 10mA, –1.5V ≤V

OUT

= 5V, I
= 5V, I

= 5mA, V

OUT

= 10mA, V

OUT

= 5mA, V

OUT

= V

SHDN

OUT

OUT

OUT

CC

= –4V ● 0.1 0.8 V

≤ –4V (LTC1261L) ● 250 1500 µs

OUT

= –4.5V (LTC1261L) ● 250 1500 µs

= –4V (LTC1261L-4) ● 250 1500 µs

OUT

= –4.5V (LTC1261L-4.5) ● 250 1500 µs

● 520 µA

● 2.5 25 µA

2

LTC1261L

LECTRICAL C CHARA TERIST

E

temperature range, otherwise specifications are at TA = 25°C, C1 = 0.1µF, C

The ● denotes the specifications which apply over the full operating

ICS

= 3.3µF unless otherwise noted. (Notes 2, 4)

OUT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OUT

I

SC

Note 1: The Absolute Maximum Ratings are those values beyond which
the life of a device may be impaired.

Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.

Note 3: The output should never be set to exceed V

Output Regulation (LTC1261L) 2.70V ≤ VCC ≤ 5.25V, 0mA ≤ I

3.25V ≤ V

≤ 5.25V, 0mA ≤ I

CC

2.70V ≤ VCC ≤ 5.25V, 0mA ≤ I

2.95V ≤ V

3.50V ≤ V

≤ 5.25V, 0mA ≤ I

CC

≤ 5.25V, 0mA ≤ I

CC

2.95V ≤ VCC ≤ 5.25V, 0mA ≤ I

3.30V ≤ V

3.85V ≤ V

≤ 5.25V, 0mA ≤ I

CC

≤ 5.25V, 0mA ≤ I

CC

3.40V ≤ VCC ≤ 5.25V, 0mA ≤ I

3.70V ≤ V

4.25V ≤ V

≤ 5.25V, 0mA ≤ I

CC

≤ 5.25V, 0mA ≤ I

CC

3.85V ≤ VCC ≤ 5.25V, 0mA ≤ I

4.10V ≤ V

4.60V ≤ V

≤ 5.25V, 0mA ≤ I

CC

≤ 5.25V, 0mA ≤ I

CC

Output Regulation 4.35V ≤ VCC ≤ 5.25V, 0mA ≤ I
(LTC1261L/LTC1261L-4) 4.60V ≤ V

5.10V ≤ V

≤ 5.25V, 0mA ≤ I

CC

≤ 5.25V, 0mA ≤ I

CC

Output Regulation 4.75V ≤ VCC ≤ 5.25V, 0mA ≤ I
(LTC1261L/LTC1261L-4.5) 5.05V ≤ V

Output Short-Circuit Current V

OUT

≤ 5.25V, 0mA ≤ I

CC

= 0V, VCC = 5.25V ● 100 220 mA

Note 4: The LTC1261L is guaranteed to meet specified performance from
0°C to 70°C and is designed, characterized and expected to meet these
extended commercial temperature limits, but is not tested at –40°C and
85°C. Guaranteed I grade parts are available, consult factory.

Note 5: The LTC1261L-4 and LTC1261L-4.5 will operate with less than the

– 10.8V.

CC

minimum V
not guaranteed to meet the ±3.5% V

≤ 10mA ● –1.552 –1.5 – 1.448 V

OUT

≤ 20mA ● –1.552 –1.5 – 1.448 V

OUT

≤ 5mA ● –2.070 –2.0 – 1.930 V

OUT

≤ 10mA ● –2.070 –2.0 – 1.930 V

OUT

≤ 20mA ● –2.070 –2.0 – 1.930 V

OUT

≤ 5mA ● –2.587 –2.5 – 2.413 V

OUT

≤ 10mA ● –2.587 –2.5 – 2.413 V

OUT

≤ 20mA ● –2.587 –2.5 – 2.413 V

OUT

≤ 5mA ● –3.105 –3.0 – 2.895 V

OUT

≤ 10mA ● –3.105 –3.0 – 2.895 V

OUT

≤ 20mA ● –3.105 –3.0 – 2.895 V

OUT

≤ 5mA ● –3.622 –3.5 – 3.378 V

OUT

≤ 10mA ● –3.622 –3.5 – 3.378 V

OUT

≤ 20mA ● –3.622 –3.5 – 3.378 V

OUT

≤ 5mA ● –4.140 –4.0 – 3.860 V

OUT

≤ 10mA ● –4.140 –4.0 – 3.860 V

OUT

≤ 20mA ● –4.140 –4.0 – 3.860 V

OUT

≤ 5mA ● –4.657 –4.5 – 4.343 V

OUT

≤ 10mA ● –4.657 –4.5 – 4.343 V

OUT

specified in the electrical characteristics table, but they are

CC

specification.

OUT

W

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TYPICAL PERFORMANCE CHARACTERISTICS

Output Voltage vs Output Current

0

TA = 25°C

–0.25

–0.50

–0.75

–1.00

–1.25

–1.50

OUTPUT VOLTAGE (V)

–1.75

–2.00

–2.25

= –2V

V

OUT

0

VCC = 2.7V

V

= 3V

CC

1052515 30

OUTPUT CURRENT (mA)

20

1261L G01

–3.0

TA = 25°C

–3.1

V

= –4V

OUT

–3.2
–3.3
–3.4
–3.5
–3.6
–3.7
–3.8

OUTPUT VOLTAGE (V)

–3.9
–4.0
–4.1
–4.2

0

5

OUTPUT CURRENT (mA)

VCC = 4.5V

VCC = 5V

10 15 20

(See Test Circuits)

–1.90

–1.95

–2.00

OUTPUT VOLTAGE (V)

–2.05

25 30

1261L G02

–2.10

Output Voltage vs Supply VoltageOutput Voltage vs Output Current

V

= –2V

OUT

TA = –40°C

T

= 85°C

A

2.5 3.0 3.5 4.0 4.5 5.0

TA = 25°C

SUPPLY VOLTAGE (V)

1261L G03

3

LTC1261L

TEMPERATURE (°C)

–55

1.21

REFERENCE VOLTAGE (V)

1.22

1.23

1.24

1.25

–35 –15 5 25

1261L G09

45 65 85 105 125

VCC = 5V
ADJ = 0V

TEMPERATURE (°C)

–40

SHORT-CIRCUIT CURRENT (mA)

80

100

120

80

1261L G12

60

40

0

–10

20

50

–25 95

5

35

65

20

160

140

VCC = 5.25V

VCC = 5V

VCC = 3V

VCC = 2.7V

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TYPICAL PERFORMANCE CHARACTERISTICS

(See Test Circuits)

Output Voltage vs Supply Voltage

–3.85

V

= –4V

OUT

–3.90

–3.95

–4.00

–4.05

OUTPUT VOLTAGE (V)

–4.10

–4.15

4.5

TA = –40°C

TA = 85°C

4.7 4.9

4.6 4.8
SUPPLY VOLTAGE (V)

TA = 25°C

5.0

Supply Current vs Supply Voltage

3.0
V

= –2V

OUT

= 0

I

OUT

2.5

2.0

1.5

= 85°C

T

1.0

SUPPLY CURRENT (mA)

0.5

0

A

TA = –40°C

3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)

5.1

TA = 25°C

5.2

1261L G04

5.02.5

1261L G07

5.3

Minimum Required V
vs V

and I

OUT

5.6

5.2

4.8

4.4

4.0

3.6

3.2

2.8

POSITIVE SUPPLY VOLTAGE (V)

2.4

2.0
–5

5.0
V

= –4.5V

OUT

4.5

I

= 0

OUT

4.0

3.5

3.0

2.5

2.0

1.5

SUPPLY CURRENT (mA)

1.0

0.5

0

4.5

4.6 4.8

OUT

I

OUT

I

= 5mA I

OUT

–4 –3 0

OUTPUT VOLTAGE (V)

T

= 25°C

A

T

= –40°C

A

4.7

4.9

SUPPLY VOLTAGE (V)

CC

= 20mA

OUT

–2 –1

TA = 85°C

5.0

= 10mA

5.1

1261L G05

5.2

1261L G08

5.3

Maximum Output Current
vs Supply Voltage

80

TA = 25°C

70

60

50

40

30

20

MAXIMUM OUTPUT CURRENT (mA)

10

0

2.7

3.0 5.4

V

= –2V

OUT

V

= –3V

OUT

3.3

3.9

3.6

SUPPLY VOLTAGE (V)

V

4.2

Reference Voltage
vs TemperatureSupply Current vs Supply Voltage

OUT

= –4V

4.5

4.8

5.1

1261L G06

Oscillator Frequency
vs Temperature

725

TA = 25°C
V

OUT

700

V

CC

675

650

625

600

575

OSCILLATOR FREQUENCY (kHz)

550

525

–40

–25 95

4

= –4V

= 5V

–10

20

5

TEMPERATURE (°C)

35

Output Short-Circuit Current
vs TemperatureStart-Up Time vs Supply Voltage

0.7

TA = 25°C

= 10mA

I

OUT

0.6

0.5

V

= –4V

= –2V

3.5

OUT

4.0

4.5

5.0

1261L G11

0.4

0.3

0.2

START-UP TIME (ms)

0.1

80

50

65

1261L G10

0

2.5

V

OUT

3.0
SUPPLY VOLTAGE (V)