Linear Technology LT1110 Datasheet

L T1110

LOAD CURRENT (mA)

0

EFFICIENCY (%)

50

60

70

80

85

90

10 20 30 40

LT1110 • TA02

75

65

55

5152535

V

IN

= 1.50V

VIN = 1.25V

VIN = 1.00V

Micropower

DC-DC Converter

Adjustable and Fixed 5V, 12V

EATU

F

■

Operates at Supply Voltages From 1.0V to 30V

■

Works in Step-Up or Step-Down Mode

■

Only Three External Off-the-Shelf Components

RE

S

Required

■

Low-Battery Detector Comparator On-Chip

■

User-Adjustable Current Limit

■

Internal 1A Power Switch

■

Fixed or Adjustable Output Voltage Versions

■

Space-Saving 8-Pin MiniDIP or S8 Package

U

O

PPLICATI

A

■

Pagers

■

Cameras

■

Single-Cell to 5V Converters

■

Battery Backup Supplies

■

Laptop and Palmtop Computers

■

Cellular Telephones

■

Portable Instruments

■

Laser Diode Drivers

■

Hand-Held Inventory Computers

S

DUESCRIPTIO

The LT1110 is a versatile micropower DC-DC converter.
The device requires only three external components to
deliver a fixed output of 5V or 12V. The very low minimum
supply voltage of 1.0V allows the use of the LT1110 in
applications where the primary power source is a single
cell. An on-chip auxiliary gain block can function as a low
battery detector or linear post regulator.

The 70kHz oscillator allows the use of surface mount
inductors and capacitors in many applications. Quiescent
current is just 300µA, making the device ideal in remote or
battery powered applications where current consumption
must be kept to a minimum.

The device can easily be configured as a step-up or
step-down converter, although for most step-down
applications or input sources greater than 3V, the LT1111
is recommended. Switch current limiting is user-adjustable
by adding a single external resistor. Unique reverse battery
protection circuitry limits reverse current to safe, non­destructive levels at reverse supply voltages up to 1.6V.

A

PPLICATITYPICAL

All Surface Mount

Single Cell to 5V Converter

SUMIDA

CD54-470K

47µH

1

I

LIM

1.5V
AA CELL*

OPERATES WITH CELL VOLTAGE 1.0V

*ADD 10 F DECOUPLING CAPACITOR IF BATTERY

µ

IS MORE THAN 2" AWAY FROM LT1110.

LT1110-5

GND SW2

54

V

SENSE

IN

2

SW1

≥

3

8

U

O

MBRS120T3

+

5V

15µF
TANTALUM

LT1110 • TA01

Efficiency

1

LT1110

WU

U

PACKAGE

/

O

RDER I FOR ATIO

A

W

O

LUTEXI T

S

A

WUW

ARB

U
G

I

S

Supply Voltage, Step-Up Mode................................ 15V

Supply Voltage, Step-Down Mode ........................... 36V

SW1 Pin Voltage...................................................... 50V

SW2 Pin Voltage.........................................– 0.5V to V

Feedback Pin Voltage (LT1110) .............................. 5.5V

Switch Current........................................................ 1.5A

Maximum Power Dissipation ............................. 500mW

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

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

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

TOP VIEW



I

1

LIM



V

2

IN

Consult factory for Industrial and Military grade parts.

IN

SW1

3

SW2

4

N8 PACKAGE

8-LEAD PLASTIC DIP

*FIXED VERSIONS

T

= 90°C, θJA = 130°C/W

JMAX

I

1



LIM

V



2

IN

SW1

3

SW2

4

S8 PACKAGE

8-LEAD PLASTIC SOIC

*FIXED VERSIONS

T

= 90°C, θJA = 150°C/W

JMAX

TOP VIEW

FB (SENSE)*

8

SET

7

A0

6

GND

5



FB (SENSE)*

8

SET

7

A0

6

GND

5

ORDER PART

NUMBER

LT1110CN8
LT1110CN8-5
LT1110CN8-12

LT1110CS8
LT1110CS8-5
LT1110CS8-12

S8 PART MARKING

1110
11105
11012

LECTRICAL C CHARA TERIST

E

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

Q

V

IN

V

OUT

f

OSC

DC Duty Cycle Full Load (VFB < V
t

ON

I

FB

I

SET

V

AO

Quiescent Current Switch Off ● 300 µA
Input Voltage Step-Up Mode ● 1.15 12.6 V

Step-Down Mode ● 30 V
Comparator Trip Point Voltage LT1110 (Note 1) ● 210 220 230 mV
Output Sense Voltage LT1110-5 (Note 2) ● 4.75 5.00 5.25 V

LT1110-12 (Note 2) ● 11.4 12.00 12.6 V
Comparator Hysteresis LT1110 ● 48 mV
Output Hysteresis LT1110-5 ● 90 180 mV

LT1110-12 ● 200 400 mV
Oscillator Frequency ● 52 70 90 kHz

Switch ON Time ● 7.5 10 12.5 µs
Feedback Pin Bias Current LT1110, VFB = 0V ● 70 150 nA
Set Pin Bias Current V
AO Output Low I
Reference Line Regulation 1.0V ≤ VIN ≤ 1.5V ● 0.35 1.0 %/V

AO

1.5V ≤ VIN ≤ 12V ● 0.05 0.1 %/V

ICS

= V

SET

REF

= –300µA, V

TA = 25°C, VIN = 1.5V, unless otherwise noted.

1.0 12.6 V

) ● 62 69 78 %

REF

● 100 300 nA

= 150mV ● 0.15 0.4 V

SET

2

L T1110

LECTRICAL C CHARA TERIST

E

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

CESAT

A

V

I

REV

I

LIM

I

LEAK

V

SW2

The ● denotes the specifications which apply over the full operating
temperature range.

Note 1: This specification guarantees that both the high and low trip point
of the comparator fall within the 210mV to 230mV range.

Note 2: This specification guarantees that the output voltage of the fixed
versions will always fall within the specified range. The waveform at the
sense pin will exhibit a sawtooth shape due to the comparator hysteresis.

Switch Saturation Voltage VIN = 1.5V, ISW = 400mA 300 400 mV
Step-Up Mode ● 600 mV

VIN = 1.5V, ISW = 500mA 400 550 mV

VIN = 5V, ISW = 1A 700 1000 mV
A2 Error Amp Gain RL = 100kΩ (Note 3) ● 1000 5000 V/V
Reverse Battery Current (Note 4) 750 mA
Current Limit 220Ω Between I
Current Limit Temperature – 0.3 %/°C

Coefficient
Switch OFF Leakage Current Measured at SW1 Pin 1 10 µA
Maximum Excursion Below GND I

SW1

TA = 25°C, V

ICS

LIM

≤ 10µA, Switch Off – 400 – 350 mV

= 1.5V, unless otherwise noted.

IN

● 750 mV

and V

IN

Note 3: 100kΩ resistor connected between a 5V source and the AO pin.
Note 4: The LT1110 is guaranteed to withstand continuous application of

+1.6V applied to the GND and SW2 pins while VIN, I
grounded.

400 mA

, and SW1 pins are

LIM

UW

Y

PICA

100

90

80

70

60

OSCILLATOR FREQUENCY (KHz)

50

40

LPER

F

O

R

AT

Oscillator Frequency Oscillator Frequency Switch On Time

–50

–25 0

TEMPERATURE (°C)

25

50

75

LT1110 • TPC01

CCHARA TERIST

E

C

80
78
76

74
72
70

68

FREQUENCY (KHz)

66
64
62

100

60

36

0

ICS

15 18 21

912

INPUT VOLTAGE (V)

242730

LT1110 • TPC02

14

13

12

11

10

ON TIME (µs)

9

8

7

–50 –25 0 25

50 75 100

TEMPERATURE (°C)

LT1110 • TPC03

3

LT1110

I (A)

0

0

V (V)

0.2

0.4

0.6

1.2

1.4

0.2 0.4 0.8 1.2

LT1110 • TPC06

1.0

1.4 1.6

SWITCH

CESAT

V

IN

= 1.0V

V = 1.2V

IN

V

IN

= 1.5V

V

IN

= 5.0V

V = 2.0V

IN

0.6 1.0

0.8

V

IN

= 3.0V

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

0

LT1110 • TPC09

3

400

380
360
340
320

280
260

6

240
220

200

300

912151821242730

R

LIM

(Ω)

SWITCH CURRENT (A)

10

LT1110 • TPC12

100

1.5

1.3

1.1

0.9

1000

0.7

0.5

0.3

0.1

STEP-DOWN MODE
V

IN

= 12V

UW

Y

PICA

78
76
74
72
70
68
66

DUTY CYCLE (%)

64

62
60

58

–50 –25 0 25

1.4

1.2

1.0

0.8

0.6

ON VOLTAGE (V)

0.4

0.2

0

LPER

F

O

R

AT

CCHARA TERIST

E

C

ICS

Saturation Voltage

Duty Cycle Switch Saturation Voltage Step-Up Mode

50 75 100

TEMPERATURE (°C)

LT1110 • TPC04

500

VIN = 1.5V

450
400
350
300

(mV)

250

CESAT

200

V

150
100

50

0

= 500mA

I

SW

–50 – 25 0 25

50 75 100

TEMPERATURE (°C)

LT1110 • TPC05

Switch On Voltage Minimum/Maximum Frequency vs
Step-Down Mode On Time Quiescent Current

VIN = 12V

0 0.2 0.4 0.6

I

(A)

SWITCH

0.8 1.0

LT1110 • TPC07

100

95
90

85
80

75
70


65
60
55

OSCILLATOR FREQUENCY (KHz)

50
45

40

7

9

8

10

SWITCH ON TIME (µs)

0°C ≤ TA ≤ 70°C

11

12

LT1110 • TPC08

13

500

450

400

350

300

250

200

QUIESCENT CURRENT (µA)

150

100

–50

4

Quiescent Current R

–25

0 25 50 75 100

TEMPERATURE (°C)

LT1110 • TPC10

1.5

1.3

1.1

0.9

0.7

0.5

SWITCH CURRENT (A)

0.3

0.1

Maximum Switch Current vs Maximum Switch Current vs

Step-Up R

LIM

STEP-UP MODE

≤ 5V

V

IN

10

100

R

(Ω)

LIM

1000

LT1110 • TPC11

Step-Down

LIM

UW

Y

PICA

160

140

120

100

80

60

BIAS CURRENT (nA)

40

20

0

–50

LPER

Set Pin Bias Current FB Pin Bias Current Reference Voltage

–25

0 25 50 75 100

TEMPERATURE (°C)

F

O

R

AT

LT1110 • TPC13

CCHARA TERIST

E

C

120
110

100

90
80
70

60
50
40

BIAS CURRENT (nA)

30
20
10

0

–25

–50

ICS

0 25 50 75 100

TEMPERATURE (°C)

LT1110 • TPC14

226

224

222

220

(mV)

REF

218

V

216

214

212

–50 –25 0 25

50 75 100

TEMPERATURE (°C)

L T1110

LT1110 • TPC15

U

PI

I

FUUC

(Pin 1): Connect this pin to VIN for normal use. Where

LIM

TI

O

U

S

lower current limit is desired, connect a resistor between
I

and VIN. A 220Ω resistor will limit the switch current

LIM

to approximately 400mA.

V

(Pin 2): Input supply voltage.

IN

SW1 (Pin 3): Collector of power transistor. For step-up

mode connect to inductor/diode. For step-down mode
connect to VIN.

SW2 (Pin 4): Emitter of power transistor. For step-up

mode connect to ground. For step-down mode connect to
inductor/diode. This pin must never be allowed to go more
than a Schottky diode drop below ground.

W

LT

1110

BLOCK

IDAGRA

V

IN

SET

+

A2

–

GAIN BLOCK/ERROR AMP

GND (Pin 5): Ground.
AO (Pin 6): Auxiliary Gain Block (GB) output. Open collector,

can sink 300µA.
SET (Pin 7): GB input. GB is an op amp with positive input

connected to SET pin and negative input connected to
220mV reference.

FB/SENSE (Pin 8): On the LT1110 (adjustable) this pin
goes to the comparator input. On the LT1110-5 and
LT1110-12, this pin goes to the internal application resistor
that sets output voltage.

AO

220mV

REFERENCE

GND

I

LIM

A1

COMPARATOR

FB

OSCILLATOR

DRIVER

SW1

Q1

SW2

LT1110 • BD01

5