LTC4425IMSE datasheet, PDF - EEWORLD Datasheet

Electrical Specifications Subject to Change

FEATURES

n

LTC4425

Linear SuperCap Charger

with Current-Limited Ideal

Diode and V/I Monitor

DESCRIPTION

The LTC

®

4425 is a constant-current/constant-voltage linear

charger designed to charge a 2-cell supercap stack from

either a Li-Ion/Polymer battery, a USB port, or a 2.7V to

5.5V current-limited supply. The part operates as an ideal

diode with an extremely low 50mΩ on-resistance making it

suitable for high peak-power/low average power applications.

The LTC4425 charges the output capacitors to an externally

programmed output voltage in LDO mode at a constant

charge current, or to V

IN

in normal mode with a smart charge

current proﬁle to limit the inrush current until the V

IN

to V

OUT

differential is less than 250mV. In addition the LTC4425 can

be set to clamp the output voltage to 4.9V or 5.4V.

Charge current (V

OUT

current limit) is programmed by

connecting a resistor between PROG and GND. The

voltage on the PROG pin represents the current ﬂowing

from V

IN

to V

OUT

for current monitoring. An internal active

balancing circuit maintains equal voltages across each

supercapacitor and clamps the peak voltage across each

cell to a pin-selectable maximum value. The LTC4425

operates at a very low 20μA quiescent current (shutdown

current <3μA) and is available in a low proﬁle 12-pin

3mm

×

3mm DFN or a 12-lead MSOP package.

50mΩ Ideal Diode from V

IN

to V

OUT

Smart Charge Current Proﬁle Limits Inrush Current

Internal Cell Balancer (No External Resistors)

Programmable Output Voltage (LDO Mode)

Programmable V

IN

to V

OUT

Current Limit

Continuous Monitoring of V

IN

to V

OUT

Current via

PROG Pin

Low Quiescent Current: 20μA

V

IN

Power Fail, PGOOD Indicator

2.45V/2.7V Cell Protection Shunts

(4.9V/5.4V SuperCap Max Top-Off Voltage)

3A Peak Current Limit, Thermal Limiting

Tiny Application Circuit, 3mm

×

3mm

×

0.75mm DFN

and 12-Lead MSOP Packages

APPLICATIONS

n

High Peak Power Battery/USB Powered Equipment

Industrial PDAs

Portable Instruments/Monitoring Equipment

Power Meters, SuperCap Backup Circuits

PC Card/USB Modems

L,

LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

Charging 2-Cell Series Supercapacitor from Li-Ion Source

0.6

V

IN

Li-Ion

1.5M

PFI

1F

V

MID

1F

V

OUT

V

IN

TO HIGH PEAK

POWER LOAD

CHARGE CURRENT (A)

0.5

0.4

0.3

0.2

0.1

I

MONITOR

2k

GND

4425 TA01

Charge Current vs V

IN

to V

OUT

FULL CHARGE CURRENT

V

FB

= V

IN

+

1.2M

–

FB

V

IN

CURRENT LIMITED

BY PMOS RDSON

1/10 CHARGE

CURRENT

IDEAL DIODE

FORWARD VOLTAGE = 15mV

PFI_RET

SEL

EN

LTC4425

PFO

PROG

470k

2.45V/2.7V

0

0.2

0.4

0.6

V

IN

– V

OUT

(V)

0.8

1

4425 TA02

4425p

1

LTC4425

ABSOLUTE MAXIMUM RATINGS

(Notes 1, 2)

V

IN

, V

OUT

, V

MID

, FB, PFI_RET,

PFO

Voltage .– 0.3V to 6V

EN, SEL, PFI Voltage ....–0.3V to MAX(V

IN

, V

OUT

) + 0.3V

Operating Junction Temperature ............– 40°C to 125°C

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

Lead Temperature, MSOP Only

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

PIN CONFIGURATION

TOP VIEW

V

OUT

V

OUT

PROG

SEL

FB

EN

1

2

3

4

5

6

13

GND

12 V

IN

11 V

IN

10 V

MID

9 PFI

8

PFO

7 PFI_RET

V

OUT

V

OUT

PROG

SEL

FB

EN

1

2

3

4

5

6

TOP VIEW

12

11

10

9

8

7

V

IN

V

IN

V

MID

PFI

PFO

PFI_RET

13

GND

DD PACKAGE

12-LEAD (3mm 3mm) PLASTIC DFN

T

JMAX

= 110°C,

θ

JA

= 43°C/W (Note 3)

EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB

MSE PACKAGE

12-LEAD PLASTIC MSOP

T

JMAX

= XXX°C,

θ

JA

= 35°C/W (Note 3)

EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

LTC4425EDD#PBF

LTC4425IDD#PBF

LTC4425EMSE#PBF

LTC4425IMSE#PBF

TAPE AND REEL

LTC4425EDD#TRPBF

LTC4425IDD#TRPBF

LTC4425EMSE#TRPBF

LTC4425IMSE#TRPBF

PART MARKING*

LFMQ

4425

PACKAGE DESCRIPTION

12-Lead (3mm

×

3mm) Plastic DFN

12-Lead (3mm

×

3mm) Plastic DFN

12-Lead Plastic MSOP

TEMPERATURE RANGE

–40°C to 125°C

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container.

For more information on lead free part marking, go to:

http://www.linear.com/leadfree/

For more information on tape and reel speciﬁcations, go to:

http://www.linear.com/tapeandreel/

4425p

2

LTC4425

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER

V

IN

I

Q(IN)

I

Q(OUT)

I

SD

V

FWD

R

FWD

The

l

denotes the speciﬁcations which apply over the full operating

junction temperature range, otherwise speciﬁcations are at T

A

= T

J

= 25°C, V

IN

= 3.8V. (Note 4)

CONDITIONS

l

MIN

2.7

TYP

20

3

MAX

5.5

UNITS

V

μA

Operating Supply Range

Quiescent Current from V

IN

Quiescent Current from V

OUT

Quiescent Current in Shutdown

Forward Voltage

Open Loop Forward On-Resistance

Feedback Voltage

Feedback Pin Input Leakage

Charge Current in LDO Mode

(FB = 0V)

Charge Current in Normal Mode (FB = V

IN

)

R

PROG

= 0.5k

R

PROG

= 5k

R

PROG

= 0.5k, V

IN

– V

OUT

< 250mV

R

PROG

= 0.5k, V

IN

– V

OUT

> 750mV

R

PROG

= 5k, V

IN

– V

OUT

< 250mV

R

PROG

= 5k, V

IN

– V

OUT

> 750mV

V

IN

= V

OUT

V

IN

= V

OUT

EN = 0

3

15

50

l

μA

mV

mΩ

Ideal Diode

Supercap Charger

V

FB

I

FB

I

CHG

1.18

1.2

100

2

0.2

2

0.2

200

20

1.00

1000

V

IN

– V

OUT

< 250mV

V

IN

– V

OUT

> 750mV

PROG Pin Shorted to GND, FB = 0

FB = 0

V

OUT

= 0, FB = 0, R

PROG

= 0.5k

2

1.00

0.1

3

1.5

105

4

1.22

V

nA

A

mA

V

mA/mA

V

A

ms

°C

V

PROG

h

PROG

V

PROG

I

SC

t

SS

T

LIM

PROG Pin Servo Voltage in LDO Mode

Ratio of Charge Current to PROG Pin Current

PROG Pin Servo Voltage in Normal Mode (FB = V

IN

)

Charger Short-Circuit Current Limit

Charger Soft Start Time

Junction Temperature in Constant Temperature

Mode (Note 5)

Maximum Voltage Across the Top Capacitor

Maximum Voltage Across the Bottom Capacitor

FB < 1.2V

Voltage Clamps

V

CLAMP

V

SEL

= Lo

V

SEL

= Hi

V

SEL

= Lo

V

SEL

= Hi

If Either Capacitor Reaches Clamp

Voltage i.e. V

OUT

< V

IN

R

PROG

= 1k, (V

OUT

– V

MID

) > V

CLAMP

R

PROG

= 1k, V

MID

> V

CLAMP

l

2.45

2.7

2.45

2.7

50

160

140

2.5

2.75

2.5

2.75

V

mV

mA

V

RIP

I

SH(TOP)

I

SH(BOT)

V

OUT

Clamp Hysteresis

Top Shunt Current

Bottom Shunt Current

4425p

3

LTC4425

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER

Leakage Balancer

V

MID

V

MID

Output Voltage

V

MID

Maximum Current Sourcing Capability

V

MID

Maximum Current Sinking Capability

PFO,

PFI_RET, PFI

Output Low Voltage (PFO, PFI_RET)

Pin Leakage Current (PFO, PFI_RET)

FB Threshold Voltage for Power Good (Rising)

V

PFI

I

PFI

PFI Threshold (Falling)

PFI Hysteresis

PFI Pin Input Leakage

Power Good Timer Delay

Logic Inputs (EN, SEL)

V

IL

V

IH

I

IH

I

IL

Logic Low Input Voltage

Logic High Input Voltage

Input Current High

Input Current Low

EN, SEL Pins at 5.5V

EN, SEL Pins at GND

l

The

l

denotes the speciﬁcations which apply over the full operating

junction temperature range, otherwise speciﬁcations are at T

A

= T

J

= 25°C, V

IN

= 3.8V. (Note 4)

CONDITIONS

V

OUT

= 3.6V

V

MID

< V

OUT/2

, V

MID

< V

CLAMP

V

MID

> V

OUT/2

, V

MID

< V

CLAMP

I

= 5mA

V

= 5V, EN = 0

LDO Mode

l

MIN

1.76

TYP

1.8

0.7

1.2

65

MAX

1.84

UNITS

V

mA

100

1

1.13

1.22

mV

μA

V

mV

V

mV

nA

ms

1.09

1.18

1.11

265

1.2

10

100

200

Input-to-Output Differential for Power Good (Rising) Normal Mode

0.4

1.2

–1

1

V

μA

Note 1:

Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2:

The current limit features of this part are intended to protect the

IC from short term or intermittent fault conditions. Continuous operation

above the maximum speciﬁed pin current rating may result in device

degradation or failure.

Note 3:

Failure to solder the exposed backside of the package to the PC

board ground plane will result in a thermal resistance much greater than

43°C/W on the DD package and greater than 35°C C/W on MSE package.

Note 4:

The LTC4425E (E grade) is guaranteed to meet speciﬁcations

from 0°C to 85°C junction temperature. Speciﬁcations over the –40°C

to 125°C operating junction temperature range are assured by design,

characterization and correlation with statistical process controls. The

LTC4425I (I grade) is guaranteed over the full –40°C to 125°C operating

junction temperature range. The junction temperature, T

J

, is calculated

from the ambient temperature, T

A

, and power dissipation, P

D

, according to

the formula:

T

J

= T

A

+ (P

D

•

θ

JA

°C/W).

Note that the maximum ambient temperature is determined by speciﬁc

operating conditions in conjunction with board layout, the rated thermal

package thermal resistance and other environmental factors.

Note 5:

V

IN

to V

OUT

charge current is reduced by thermal foldback as

junction temperature approaches 105°C.

4425p

4

LTC4425

TYPICAL PERFORMANCE CHARACTERISTICS

LDO Regulation Voltage

vs Charge Current

3.295

3.290

3.285

VOLTAGE (V)

3.280

3.275

3.270

3.265

V

IN

= 3.8V, I

OUT

= 10mA

3.260 R

PROG

= 1k

V

OUT

SET FOR 3.3V

3.255

200

400

600

800

0

I

OUT

(mA)

3.286

LDO Regulation Voltage

vs Temperature

V

IN

= 3.8V

3.285 V

OUT

SET FOR 3.3V

ON-RESISTANCE (mΩ)

3.284

3.283

V

OUT

(V)

3.282

3.281

3.280

3.279

3.278

1000

1200

3.277

–45 –30 –15

0 15 30 45 60

TEMPERATURE (°C)

75

90

80

70

Charger FET On-Resistance

vs Supply

90°C

60

25°C

50

40

30

20

10

0

2.7

3

3.3 3.6 3.9 4.2

INPUT VOLTAGE (V)

4.5

4.8

–45°C

3586 G35

4425 G02

4425 G03

Charge Current

vs (V

IN

–V

OUT

) Differential

1200

1000

CHARGE CURRENT (mA)

PROG VOLTAGE (mV)

LDO MODE (FB GROUNDED)

800

600

400

200

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

V

IN

TO V

OUT

DIFFERENTIAL (V)

4425 G04

PROG Pin Voltage

vs (V

IN

– V

OUT

) Differential

1200

1000

LDO MODE (FB GROUNDED)

CURRENT (μA)

800

NORMAL MODE

600

400

200

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

V

IN

TO V

OUT

DIFFERENTIAL (V)

4425 G05

V

IN

Quiescent Current vs Supply

and Temperature (V

IN

≥ V

OUT

)

25

V

IN

= 3.8V

V

IN

= 3.8V

R

PROG

= 1k

V

IN

= 3.8V

R

PROG

= 1k

20

15

V

IN

= 2.7V

10

NORMAL MODE

5

0

–45

–25

–5

15

35

55

TEMPERATURE (°C)

75

4425 G06

Charge Current vs Temperature in

Thermal Regulation

1200

1000

CHARGE CURRENT (mA)

800

600

400

200

0

–45 –30 –15 0 15 30 45 60 75 90 105 120

TEMPERATURE (°C)

4425 G07

Charge Current vs V

OUT

in

Thermal Regulation

3000

V

IN

= 5V

PROG PIN SHORTED TO GND

2500 FB PIN SHORTED TO GND

AMBIENT TEMP 24°C

CURRENT (μA)

2000

1500

1000

500 THERMAL REGULATION

ON-CHIP POWER DISSIPATION ~4W

CASE TEMP ~100°C

0

0 0.5 1 1.5 2 2.5 3 3.5

OUTPUT VOLTAGE (V)

20

18

16

14

12

10

8

6

4

2

4

4.5

V

OUT

Quiescent Current vs V

OUT

and Temperature (V

IN

≥ V

OUT

)

V

IN

< V

OUT

V

IN

= 3.8V

V

IN

= 3.8V, V

OUT

= 3.5V

R

PROG

= 1k, FB GROUNDED

V

OUT

= 2.7V

0

–45

–25

–5

15

35

55

TEMPERATURE (°C)

75

4425 G09

4425 G08

4425p

5

LTC4425IMSE

LTC4425IMSE Overview

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