LINEAR TECHNOLOGY LTC1751, LTC1751-3.3, LTC1751-5 Technical data

FEATURES

INPUT VOLTAGE (V)

2.5

4.8

OUTPUT VOLTAGE (V)

4.9

5.0

5.1

5.2

3.0 3.5 4.0 4.5

1751 TA02

5.0 5.5

I

OUT

= 50mA

C

FLY

= 1µF

C

OUT

= 10µF

TA = 25°C

T

A

= –40°C

TA = 85°C

■

5V Output Current: 100mA (VIN ≥ 3V)

■

3.3V Output Current: 80mA (VIN ≥ 2.5V)

■

Ultralow Power: 20µA Quiescent Current

■

Regulated Output Voltage: 3.3V ±4%, 5V ±4%, ADJ

■

No Inductors

■

Short-Circuit/Thermal Protection

■

VIN Range: 2V to 5.5V

■

800kHz Switching Frequency

■

Very Low Shutdown Current: <2µA

■

Shutdown Disconnects Load from V

■

PowerGood/Undervoltage Output

■

Adjustable Soft-Start Time

■

Available in an 8-Pin MSOP Package

IN

U

APPLICATIO S

■

Li-Ion Battery Backup Supplies

■

Local 3V and 5V Conversion

■

Smart Card Readers

■

PCMCIA Local 5V Supplies

■

White LED Backlighting

LTC1751/LTC1751-3.3/LTC1751-5

Micropower, Regulated

Charge Pump

DC/DC Converters

U

DESCRIPTIO

The LTC®1751 family are micropower charge pump DC/
DC converters that produce a regulated output voltage at
up to 100mA. The input voltage range is 2V to 5.5V.
Extremely low operating current (20µA typical with no
load) and low external parts count (one flying capacitor
and two small bypass capacitors at VIN and V
them ideally suited for small, battery-powered applica­tions.

The LTC1751 family operate as Burst ModeTM switched
capacitor voltage doublers to achieve ultralow quiescent
current. They have thermal shutdown capability and can
survive a continuous short circuit from V

OUT

PGOOD pin on the LTC1751-3.3 and LTC1751-5 indicates
when the output voltage has reached its final value and if
the output has an undervoltage fault condition. The FB pin
of the adjustable LTC1751 can be used to program the
desired output voltage or current. An optional soft-start
capacitor may be used at the SS pin to prevent excessive
inrush current during start-up.

The LTC1751 family is available in an 8-pin MSOP
package.

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

Burst Mode is a trademark of Linear Technology Corporation.

) make

OUT

to GND. The

TYPICAL APPLICATIO

V

2.7V

TO 5.5V

IN

C2

10µF

OFF ON

U

Regulated 5V Output from a 2.7V to 5.5V Input

3

V

IN

7

SHDN

LTC1751-5

8

SS

4

GND

C

= MURATA GRM39X5R105K6.3AJ

FLY

C1, C2 = MURATA GRM40X5R106K6.3AJ

V

OUT

PGOOD

1751 TA01

2

R1
100k

1

6

+

C

5

–

C

C
1µF

PGOOD

FLY

C1
10µF

V
5V ±4%
I

OUT

I

OUT

OUT

≤ 100mA, VIN ≥ 3V
≤ 50mA, VIN ≥ 2.7V

Output Voltage vs Input Voltage

1

LTC1751/LTC1751-3.3/LTC1751-5

PACKAGE/ORDER I FOR ATIO

UU

W

1
2
3
4

FB/PGOOD*

V

OUT

V

IN

GND

8
7
6
5

SS
SHDN
C

+

C

–

TOP VIEW

MS8 PACKAGE

8-LEAD PLASTIC MSOP

WWWU

ABSOLUTE AXI U RATI GS

(Note 1)

VIN to GND.................................................. –0.3V to 6V

PGOOD, FB, V

SS, SHDN to GND........................ –0.3V to (VIN + 0.3V)

V

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

OUT

I

(Note 2)....................................................... 125mA

OUT

Operating Temperature Range (Note 3) .. –40°C to 85°C

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

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

to GND ........................... –0.3V to 6V

OUT

ORDER PART

NUMBER

LTC1751EMS8
LTC1751EMS8-3.3
LTC1751EMS8-5

MS8 PART MARKING

T

= 150°C, θJA = 160°C/W

JMAX

*PGOOD ON LTC1751-3.3/LTC1751-5

FB ON LTC1751

LTKL
LTKN
LTKP

Consult factory for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. C

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
LTC1751-3.3

V

IN

V

OUT

I

CC

V

R

η Efficiency VIN = 2V, I

LTC1751-5

V

IN

V

OUT

I

CC

V

R

η Efficiency VIN = 3V, I

LTC1751

V

IN

I

CC

V

FB

I

FB

R

OUT

Input Supply Voltage ● 2 4.4 V
Output Voltage 2V ≤ VIN ≤ 4.4V, I

2.5V ≤ VIN ≤ 4.4V, I

Operating Supply Current 2V ≤ VIN ≤ 4.4V, I
Output Ripple VIN = 2.5V, I

Input Supply Voltage ● 2.7 5.5 V
Output Voltage 2.7V ≤ VIN ≤ 5.5V, I

Operating Supply Current 2.7V ≤ VIN ≤ 5.5V, I
Output Ripple VIN = 3V, I

Input Supply Voltage ● 2 5.5 V
Operating Supply Current 2V ≤ VIN ≤ 5.5V, I
FB Regulation Voltage 2V ≤ VIN ≤ 5.5V, I
FB Input Current VFB = 1.3V ● –50 50 nA
Open-Loop Charge Pump Strength VIN = 2V, V

3V ≤ V

= 2.7V, V

V

IN

The ● denotes specifications which apply over the full specified

= 1µF, CIN = 10µF, C

FLY

≤ 40mA ● 3.17 3.3 3.43 V

OUT

≤ 80mA ● 3.17 3.3 3.43 V

OUT

= 0mA, SHDN = V

OUT

= 40mA 68 mV

OUT

= 40mA 80 %

OUT

≤ 50mA ● 4.8 5 5.2 V

≤ 5.5V, I

IN

OUT
OUT

OUT

≤ 100mA ● 4.8 5 5.2 V

OUT

= 0mA, SHDN = V

OUT

= 50mA 75 mV
= 50mA 82 %

= 0mA, SHDN = V

OUT

≤ 20mA ● 1.157 1.205 1.253 V

OUT

= 3.3V (Note 5) ● 8.5 20 Ω

OUT

= 5V (Note 5) ● 6.0 12 Ω

OUT

IN

IN

= 10µF unless otherwise noted.

OUT

● 18 40 µA

IN

(Note 4 ) ● 16 40 µA

● 20 50 µA

P-P

P-P

2

LTC1751/LTC1751-3.3/LTC1751-5

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. C

The ● denotes specifications which apply over the full specified

= 1µF, CIN = 10µF, C

FLY

= 10µF unless otherwise noted.

OUT

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
LTC1751-3.3/LTC1751-5

UVL PGOOD Undervoltage Low Threshold Relative to Regulated V
UVH PGOOD Undervoltage High Threshold Relative to Regulated V
V

OL

I

OH

PGOOD Low Output Voltage I
PGOOD High Output Leakage V

= –500µA ● 0.4 V

PGOOD

= 5.5V ● 1 µA

PGOOD

(Note 6) ● –11 –7 –3 %

OUT

(Note 6) ● –8 –4.5 –2 %

OUT

LTC1751/LTC1751-3.3/LTC1751-5

I

SHDN

V

IH

V

IL

I

IH

I

IL

t

r

f

OSC

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

Note 2: Based on long term current density limitations.
Note 3: The LTC1751EMS8-X is guaranteed to meet performance

Shutdown Supply Current VIN ≤ 3.6V, V

3.6V < V

= 0V, V

OUT

, V

= 0V, V

IN

OUT

= 0V ● 0.01 2 µA

SHDN

= 0V ● 5 µA

SHDN

SHDN Input Threshold (High) ● 1.5 V
SHDN Input Threshold (Low) ● 0.3 V
SHDN Input Current (High) SHDN = V

IN

● –1 1 µA

SHDN Input Current (Low) SHDN = 0V ● –1 1 µA
V

Rise Time VIN = 3V, I

OUT

= 0mA, 10% to 90% (Note 6) 0.6ms/nF • C

OUT

SS

sec

Switching Frequency Oscillator Free Running 800 kHz

Note 4: The no load input current will be approximately I

plus twice the

CC

standing current in the resistive output divider.
Note 5: R

≡ (2VIN – V

OUT

OUT

)/I

OUT

.

Note 6: See Figure 2.

specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

(LTC1751-3.3)

Output Voltage vs Load Current

3.40
TA = 25°C

= 1µF

C

FLY

3.35

3.30

VIN = 2V

OUTPUT VOLTAGE (V)

3.25

3.20

0

25 50 75 100

LOAD CURRENT (mA)

VIN = 2.5V

125 150

1751 G01

Output Voltage vs Input Voltage

3.40
I

= 40mA

OUT

= 1µF

C

FLY

C

= 10µF

OUT

3.35

3.30

OUTPUT VOLTAGE (V)

3.25

3.20

2.0

2.5
INPUT VOLTAGE (V)

3.0

TA = 25°C

3.5

TA = –40°C

TA = 85°C

4.0

1751 G02

4.5

No Load Supply Current
vs Input Voltage

40

I

= 0mA

OUT

= 1µF

C

FLY

V

= V

SHDN

30

20

SUPPLY CURRENT (µA)

10

0

2.0

IN

2.5

3.0

INPUT VOLTAGE (V)

TA = 85°C

TA = 25°C

TA = –40°C

3.5

4.0

4.5

1751 G03

3

LTC1751/LTC1751-3.3/LTC1751-5

UW

TYPICAL PERFOR A CE CHARACTERISTICS

(LTC1751-3.3)

Power Efficiency vs Load Current

100

TA = 25°C

90

= 1µF

C

FLY

= 10µF

C

OUT

80
70
60

50

40

EFFICIENCY (%)

30
20
10

0

0.001

VIN = 2V

VIN = 2.75V

VIN = 3.3V

VIN = 4.4V

0.01 0.1 1 10 100
LOAD CURRENT (mA)

1751 G04

250

200

150

OUTPUT CURRENT (mA)

100

50

2.0

Short-Circuit Output Current
vs Input Voltage

TA = 25°C
C

= 1µF

FLY

2.5
INPUT VOLTAGE (V)

3.0

3.5

4.0

4.5

1751 G05

Start-Up

SHDN

2V/DIV

PGOOD

5V/DIV

V

OUT

1V/DIV

CSS = 10nF 2ms/DIV 1751 G06

(LTC1751-5)

Output Voltage vs Output Current

5.2
TA = 25°C

C

5.1

5.0

OUTPUT VOLTAGE (V)

4.9

FLY

= 1µF

AC COUPLED

V

IN

VIN = 2.7V

Output Ripple

V

OUT

50mV/DIV

VIN = 2.5V 5µs/DIV 1751 G07
I

= 80mA

OUT

C

= 10µF

OUT

= 3V

40mA/DIV

AC COUPLED

50mV/DIV

No Load Supply Current
vs Input Voltage

40

C

= 1µF

FLY

= 0

I

OUT

= V

V

SHDN

30

20

SUPPLY CURRENT (µA)

10

IN

TA = –40°C

Load Transient Response

I

OUT

V

OUT

VIN = 2.5V 50µs/DIV 1751 G08

TA = 85°C

TA = 25°C

4

4.8

0

50

100

OUTPUT CURRENT (mA)

150

200

1751 G09

0

2.5

3.0 3.5 4.0 4.5
INPUT VOLTAGE (V)

5.0 5.5

1751 G10