LTC3826IUH-PBF datasheet, PDF - EEWORLD Datasheet

FEATURES

n

LTC3826

30µA I

Q

, Dual, 2-Phase

Synchronous Step-Down Controller

DESCRIPTION

The LTC

®

3826 is a high performance dual step-down

switching regulator controller that drives all N-channel

synchronous power MOSFET stages. A constant frequency

current mode architecture allows a phase-lockable fre-

quency of up to 650kHz. Power loss and noise due to the

ESR of the input capacitor are minimized by operating the

two controller output stages out of phase.

The 30μA no-load quiescent current extends operating

life in battery powered systems. OPTI-LOOP compensa-

tion allows the transient response to be optimized over

a wide range of output capacitance and ESR values. The

LTC3826 features a precision 0.8V reference and a power

good output indicator. A wide 4V to 36V input supply range

encompasses all battery chemistries.

Independent TRACK/SS pins for each controller ramp the

output voltage during start-up. Current foldback limits

MOSFET heat dissipation during short-circuit conditions.

The PLLIN/MODE pin selects among Burst Mode opera-

tion, pulse skipping mode, or continuous inductor cur-

rent mode at light loads. For a leaded package version

(28-lead SSOP), see the LTC3826-1 data sheet.

L,

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

Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners. Protected by U.S. Patents,

including 5481178, 5929620, 6177787, 6144194, 5408150, 6580258, 6304066, 5705919.

Wide Output Voltage Range: 0.8V ≤ V

OUT

≤ 10V

Ultralow Operating I

Q

: 30μA (One Channel On)

Out-of-Phase Controllers Reduce Required Input

Capacitance and Power Supply Induced Noise

OPTI-LOOP

®

Compensation Minimizes C

OUT

±1% Output Voltage Accuracy

Wide V

IN

Range: 4V to 36V Operation

Phase-Lockable Fixed Frequency 140kHz to 650kHz

Selectable Continuous, Pulse Skipping or

Low Ripple

Burst Mode

®

Operation at Light Loads

Dual N-Channel MOSFET Synchronous Drive

Very Low Dropout Operation: 99% Duty Cycle

Adjustable Output Voltage Soft-Start or Tracking

Output Current Foldback Limiting

Power Good Output Voltage Monitor

Output Overvoltage Protection

Low Shutdown I

Q

: 4μA

Internal LDO Powers Gate Drive from V

IN

or V

OUT

Small 5mm

×

5mm QFN Package

APPLICATIONS

n

Automotive Systems

Battery-Operated Digital Devices

Distributed DC Power Systems

TYPICAL APPLICATION

High Efﬁciency Dual 8.5V/3.3V Step-Down Converter

V

IN

4V TO 36V

4.7μF

V

IN

TG1

3.3μH

0.1μF

BOOST1

SW1

BG1

LTC3826

SENSE1

+

0.015Ω

V

OUT1

3.3V

5A

SENSE1

–

V

FB1

62.5k

150μF

220pF

20k

15k

I

TH1

SENSE2

–

V

FB2

I

TH2

220pF

15k

20k

192.5k

INTV

CC

TG2

EFFICIENCY (%)

BOOST2

SW2

BG2

PGND

SENSE2

+

0.015Ω

V

OUT2

8.5V

3.5A

150μF

0.1μF

7.2μH

22μF

50V

100

90

80

70

60

50

40

30

20

10

FIGURE 13 CIRCUIT

0

0.1

0.00001 0.0001 0.001 0.01

0.1

1

10

OUTPUT CURRENT (A)

3826 TA01b

Efﬁciency and Power Loss

vs Load Current

10000

1000

POWER LOSS (mW)

100

10

1

TRACK/SS1 SGND TRACK/SS2

0.1μF

3826 TA01

3826fc

1

LTC3826

ABSOLUTE MAXIMUM RATINGS

(Note 1)

PIN CONFIGURATION

TOP VIEW

TRACK/SS1

SENSE1

+

PGOOD2

PGOOD1

Input Supply Voltage (V

IN

) ......................... 36V to –0.3V

Top Side Driver Voltages

(BOOST1, BOOST2) ............................... 42V to –0.3V

Switch Voltage (SW1, SW2) ......................... 36V to –5V

(BOOST1-SW1), (BOOST2-SW2) ............. 8.5V to –0.3V

RUN1, RUN2 ............................................... 7V to –0.3V

SENSE1

+

, SENSE2

+

, SENSE1

–

,

SENSE2

–

Voltages ................................ 11V to –0.3V

PLLIN/MODE, PLLLPF Voltages ........... INTV

CC

to –0.3V

,

PHASMD, FOLDDIS, TRACK/SS1, TRACK/SS2

Voltages ........................................... INTV

CC

to –0.3V

EXTV

CC

...................................................... 10V to –0.3V

I

TH1

, I

TH2

, V

FB1

, V

FB2

Voltages ................. 2.7V to –0.3V

PGOOD1, PGOOD2 Voltages ..................... 8.5V to –0.3V

Peak Output Current <10μs (TG1, TG2, BG1, BG2) .....3A

Operating Temperature Range (Note 2).... –40°C to 85°C

Junction Temperature (Note 3) ............................. 125°C

Storage Temperature Range .................. –65°C to 125°C

32 31 30 29 28 27 26 25

SENSE1

–

1

PLLLPF 2

PHASMD 3

CLKOUT 4

PLLIN/MODE 5

SGND 6

RUN1 7

RUN2 8

9 10 11 12 13 14 15 16

SENSE2

–

SENSE2

+

V

FB2

I

TH2

FOLDDIS

TG2

TRACK/SS2

SW2

33

24 BOOST1

23 BG1

22 V

IN

21 PGND

20 EXTV

CC

19 INTV

CC

18 BG2

17 BOOST2

UH PACKAGE 32-LEAD (5mm 5mm) PLASTIC QFN

T

JMAX

= 125°C,

JA

= 34°C/W

EXPOSED PAD (PIN 33) IS SGND, MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

LTC3826EUH#PBF

LTC3826IUH#PBF

LEAD BASED FINISH

LTC3826EUH

LTC3826IUH

TAPE AND REEL

LTC3826EUH#TRPBF

LTC3826IUH#TRPBF

TAPE AND REEL

LTC3826EUH#TR

LTC3826IUH#TR

PART MARKING*

3826

PART MARKING*

3826

PACKAGE DESCRIPTION

32-Lead (5mm

×

5mm) Plastic QFN

32-Lead (5mm

×

5mm) Plastic QFN

PACKAGE DESCRIPTION

32-Lead (5mm

×

5mm) Plastic QFN

32-Lead (5mm

×

5mm) Plastic QFN

TEMPERATURE RANGE

–40°C to 85°C

TEMPERATURE RANGE

–40°C to 85°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/

SW1

V

FB1

I

TH1

TG1

3826fc

2

LTC3826

ELECTRICAL CHARACTERISTICS

SYMBOL

V

FB1, 2

I

VFB1, 2

V

REFLNREG

V

LOADREG

PARAMETER

Regulated Feedback Voltage

Feedback Current

Reference Voltage Line Regulation

Output Voltage Load Regulation

Main Control Loops

(Note 4); I

TH1, 2

Voltage = 1.2V

(Note 4)

V

IN

= 4V to 30V (Note 4)

(Note 4)

Measured in Servo Loop;

ΔI

TH

Voltage = 1.2V to 0.7V

Measured in Servo Loop; ΔITH Voltage = 1.2V to 2V

I

TH1, 2

= 1.2V; Sink/Source 5mA (Note 4)

(Note 5)

RUN1 = 5V, RUN2 = 0V, V

FB1

= 0.83V (No Load)

RUN1 = OV, RUN2 = 5V, V

FB2

= 0.83V (No Load)

V

RUN1, 2

= 0V

RUN1,2 = 5V, V

FB1

= V

FB2

= 0.83V

V

IN

Ramping Down

Measured at V

FB1, 2

, Relative to Regulated V

FB1, 2

(Each Channel) V

SENSE1

–,

2

– = V

SENSE1

+,

2

+ = 0V

In Dropout

V

TRACK1, 2

= 0V

V

RUN1

, V

RUN2

Rising

V

FB1, 2

= 0.7V, V

SENSE1

–,

2

– = 3.3V

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

l

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= 12V, V

RUN/SS1, 2

= 5V unless otherwise noted.

CONDITIONS

MIN

0.792

TYP

0.800

–5

0.002

0.1

–0.1

0.5

30

4

50

3.7

8

98

0.75

0.5

85

10

–220

99.4

1

0.7

100

50

40

70

230

5.0

7.2

4.5

5.25

0.2

7.5

0.2

4.7

0.2

V

PLLLPF

= Floating; PLLIN/MODE = DC Voltage

V

PLLLPF

= 0V; PLLIN/MODE = DC Voltage

V

PLLLPF

= INTV

CC

; PLLIN/MODE = DC Voltage

PLLIN/MODE = External Clock; V

PLLLPF

= 0V

PLLIN/MODE = External Clock; V

PLLLPF

= 2V

650

350

220

475

390

250

530

115

800

430

280

585

140

5.5

1.0

7.8

1.0

1.35

0.9

115

90

80

50

10

75

4

12

MAX

0.808

–50

0.02

0.5

–0.5

UNITS

V

nA

%/V

%

mmho

μA

V

%

μA

%

μA

V

mV

ns

V

%

V

%

V

kHz

g

m1, 2

I

Q

Transconductance Ampliﬁer g

m

Input DC Supply Current

Sleep Mode (Channel 1 On)

Sleep Mode (Channel 2 On)

Shutdown

Sleep Mode (Both Channels)

Undervoltage Lockout

Feedback Overvoltage Lockout

Sense Pins Total Source Current

Maximum Duty Factor

RUN Pin ON Threshold

TG Transition Time:

Rise Time

Fall Time

BG Transition Time:

Rise Time

Fall Time

UVLO

V

OVL

I

SENSE

DF

MAX

V

RUN1, 2

ON

I

TRACK/SS1, 2

Soft-Start Charge Current

V

SENSE(MAX)

Maximum Current Sense Threshold

TG1, 2 t

r

TG1, 2 t

f

BG1, 2 t

r

BG1, 2 t

f

TG/BG t

1D

BG/TG t

2D

t

ON(MIN)

V

INTVCCVIN

V

LDOVIN

V

INTVCCEXT

V

LDOEXT

V

EXTVCC

V

LDOHYS

f

NOM

f

LOW

f

HIGH

f

SYNCMIN

f

SYNCMAX

Top Gate Off to Bottom Gate On Delay C

LOAD

= 3300pF Each Driver

Synchronous Switch-On Delay Time

Bottom Gate Off to Top Gate On Delay C

LOAD

= 3300pF Each Driver

Top Switch-On Delay Time

Minimum On-Time

Internal V

CC

Voltage

INTV

CC

Load Regulation

Internal V

CC

Voltage

INTV

CC

Load Regulation

EXTV

CC

Switchover Voltage

EXTV

CC

Hysteresis

Nominal Frequency

Lowest Frequency

Highest Frequency

Minimum Synchronizable Frequency

Maximum Synchronizable Frequency

(Note 7)

8.5V < V

IN

< 30V, V

EXTVCC

= 0V

I

CC

= 0mA to 20mA, V

EXTVCC

= 0V

V

EXTVCC

= 8.5V

I

CC

= 0mA to 20mA, V

EXTVCC

= 8.5V

EXTV

CC

Ramping Positive

INTV

CC

Linear Regulator

Oscillator and Phase-Locked Loop

3826fc

3

LTC3826

ELECTRICAL CHARACTERISTICS

SYMBOL

I

PLLLPF

PARAMETER

Phase Detector Output Current

Sinking Capability

Sourcing Capability

PGOOD Voltage Low

PGOOD Leakage Current

PGOOD Trip Level

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= 12V, V

RUN/SS1, 2

= 5V unless otherwise noted.

CONDITIONS

f

PLLIN/MODE

< f

OSC

f

PLLIN/MODE

> f

OSC

I

PGOOD

= 2mA

V

PGOOD

= 5V

V

FB

with Respect to Set Regulated Voltage

V

FB

Ramping Negative

V

FB

Ramping Positive

–12

8

–10

10

MIN

TYP

–5

5

0.1

0.3

±1

–8

12

MAX

UNITS

μA

V

μA

%

PGOOD Output

V

PGL

I

PGOOD

V

PG

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 LTC3826E is guaranteed to meet performance speciﬁcations

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

temperature range are assured by design, characterization and correlation

with statistical process controls. The LTC3826I is guaranteed to meet

performance speciﬁcations over the full –40°C to 85°C operating

temperature range.

Note 3:

T

J

is calculated from the ambient temperature T

A

and power

dissipation P

D

according to the following formulas:

T

J

= T

A

+ (P

D

• 34 °C/W)

Note 4:

The LTC3826 is tested in a feedback loop that servos V

ITH1, 2

to a

speciﬁed voltage and measures the resultant V

FB1, 2

.

Note 5:

Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. See Applications Information.

Note 6:

Rise and fall times are measured using 10% and 90% levels. Delay

times are measured using 50% levels.

Note 7:

The minimum on-time condition is speciﬁed for an inductor

peak-to-peak ripple current ≥40% of I

MAX

(see minimum on-time

considerations in the Applications Information section).

3826fc

4

LTC3826

TYPICAL PERFORMANCE CHARACTERISTICS

Efﬁciency and Power Loss

vs Output Current

100

Burst Mode OPERATION

90

PULSE SKIPPING MODE

FORCED

80

CONTINUOUS

70

60

50

40

30

20

10

V

IN

= 12V

V

OUT

= 3.3V

1

10

10000

100

90

1000

POWER LOSS (mW)

EFFICIENCY (%)

80

70

EFFICIENCY (%)

V

IN

= 12V

V

IN

= 5V

1

10

3826 G02

Efﬁciency vs Output Current

V

OUT

= 3.3V

98

96

94

92

90

88

86

84

82

Efﬁciency vs Input Voltage

EFFICIENCY (%)

100

60

50

40

30

20

10

0

0.00001 0.0001 0.001 0.01

0.1

OUTPUT CURRENT (A)

FIGURE 13 CIRCUIT

0.1

10

0

0.00001 0.0001 0.001 0.01

0.1

OUTPUT CURRENT (A)

FIGURE 13 CIRCUIT

0

5

10

15 20 25 30

INPUT VOLTAGE (V)

35

40

3826 G03

3826 G01

FIGURE 13 CIRCUIT

Load Step

(Burst Mode Operation)

V

OUT

100mV/DIV

AC

COUPLED

I

L

2A/DIV

V

OUT

100mV/DIV

AC

COUPLED

I

L

2A/DIV

20μs/DIV

FIGURE 13 CIRCUIT

V

OUT

= 3.3V

Load Step

(Forced Continuous Mode)

V

OUT

100mV/DIV

AC

COUPLED

I

L

2A/DIV

Load Step

(Pulse Skipping Mode)

3826 G04

20μs/DIV

FIGURE 13 CIRCUIT

V

OUT

= 3.3V

3826 G05

20μs/DIV

FIGURE 13 CIRCUIT

V

OUT

= 3.3V

3826 G06

Inductor Current at Light Load

FORCED

CONTINUOUS

MODE

2A/DIV

Burst Mode

OPERATION

PULSE

SKIPPING

MODE

2μs/DIV

FIGURE 13 CIRCUIT

V

OUT

= 3.3V

I

LOAD

= 100μA

3826 G07

Soft-Start-Up

V

OUT2

2V/DIV

Tracking Start-Up

V

OUT2

2V/DIV

V

OUT1

2V/DIV

V

OUT1

2V/DIV

20ms/DIV

FIGURE 13 CIRCUIT

3826 G08

20ms/DIV

FIGURE 13 CIRCUIT

3826 G09

3826fc

5

LTC3826IUH-PBF

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