ANALOG DEVICES LTC 3824 EMSE Datasheet

LTC3824

High Voltage Step-Down

Controller With 40µA

Quiescent Current

FeaTures

n

Wide Input Range: 4V to 60V

n

Current Mode Constant Frequency PWM

n

Very Low Dropout Operation: 100% Duty Cycle

n

Programmable Switching Frequency:

200kHz to 600kHz

n

Selectable High Efficient Burst Mode® Operation:

40µA Quiescent Current

n

Easy Synchronization

n

8V, 2A Gate Drive (VCC > 10V) for Industrial High

Voltage P-Channel MOSFET

n

Programmable Soft-Start

n

Programmable Current Limit

n

Available in a Small 10-Pin Thermally Enhanced

MSE Package

applicaTions

n

Industrial and Automotive Power Supplies

n

Telecom Power Supplies

n

Distributed Power Systems

DescripTion

The LTC®3824 is a step-down DC/DC controller designed
to drive an external P-channel MOSFET. With a wide input
range of 4V to 60V and a high voltage gate driver, the
LTC3824 is suitable for many industrial and automotive
high power applications. Constant frequency current mode
operation provides excellent performance.

The LTC3824 can be configured for Burst Mode operation.
Burst Mode operation enhances low current efficiency
(only 40µA quiescent current) and extends battery run
time. The switching frequency can be programmed up to
600kHz and is easily synchronizable.

Other features include current limit, soft-start, micropower
shutdown, and Burst Mode disable.

The LTC3824 is available in a 10-lead MSE power package.

L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5731964.

Typical applicaTion

V

5.5V TO 60V

33µF

100V

IN

C

IN

392k

+

0.1µF

5V/2A Buck Converter

C

CAP

0.1µF

CAP

V

CC

SENSE

LTC3824

R

SET

GND

SYNC/MODE

SS

GATE

V

FB

V

C

10k

3.3nF

R

S

0.025Ω

22µH

100pF

51Ω

422k

80.6k

3824 TA01

C

OUT

100µF
×2

Efficiency and Power Loss vs Load Current

100

EFFICIENCY

90

80

70

V

OUT

5V
2A

EFFICIENCY (%)

60

POWER LOSS

50

10 100

LOAD CURRENT (mA)

VIN = 12V

VIN = 40V

VIN = 40V

VIN = 12V

2.5

2.0

POWER LOSS (W)

1.5

1.0

0.5

0

20001000

3824 TA01a

3824fg

1

LTC3824

TOP VIEW

pin conFiguraTionabsoluTe MaxiMuM raTings

(Note 1)

VCC ...........................................................................65V

SS, R
V

C

, VFB .............................................................4V

SET

...............................................................................3V

SYNC/MODE ...............................................................6V

– V

V

CC

..............................................................1V

SENSE

Operating Junction Temperature Range

(Note 2) .................................................. –55°C to 150°C

1

GND

SYNC/MODE

EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB

2

11

3

R

SET

V

4

C

V

5

FB

MSE PACKAGE

10-LEAD PLASTIC MSOP

= 150°C, θJA = 43°C/W, θJC = 3°C/W

T

JMAX

10

CAP

9

GATE

8

V

CC

SENSE

7

SS

6

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

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

orDer inForMaTion

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC3824EMSE#PBF LTC3824EMSE#TRPBF LTBRZ 10-Lead Plastic MSOP –40°C to 125°C
LTC3824IMSE#PBF LTC3824IMSE#TRPBF LTCGZ 10-Lead Plastic MSOP –40°C to 125°C
LTC3824HMSE#PBF LTC3824HMSE#TRPBF LTCGZ 10-Lead Plastic MSOP –40°C to 150°C
LTC3824MPMSE#PBF LTC3824MPMSE#TRPBF LTCGZ 10-Lead Plastic MSOP –55°C to 150°C

LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC3824EMSE LTC3824EMSE#TR LTBRZ 10-Lead Plastic MSOP –40°C to 125°C
LTC3824IMSE LTC3824IMSE#TR LTCGZ 10-Lead Plastic MSOP –40°C to 125°C

LTC3824HMSE LTC3824HMSE#TR LTCGZ 10-Lead Plastic MSOP –40°C to 150°C
LTC3824MPMSE LTC3824MPMSE#TR LTCGZ 10-Lead Plastic MSOP –55°C to 150°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/

The l denotes the specifications which apply over the specified operating

elecTrical characTerisTics

junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VCC = 12V, R

= 392k, C

SET

= 0.1µF. No load on any

CAP

outputs, unless otherwise specified.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply Voltage (V

Supply Current (I

Supply Current (I

)

CC

) VC ≤ 0.4V (Switching Off), VCC ≤ 60V

VCC

) Burst Mode Operation VCC ≤ 60V, SYNC/MODE Open, VC = 0.6V 40 65 µA

VCC

Supply Current in Shutdown V

V

= 0V (Burst Mode Operation Disable)

SYNC

≤ 25mV, VCC ≤ 60V

C

≤ 25mV, VCC = 12V

V

C

l

4 60 V

0.8 1.3 mA

l

l

9 20

5 10

30

15

µA
µA

µA
µA

Voltage Amplifier gm

Reference Voltage (V

)

REF

LTC3824E/LTC3824I

LTC3824MP/LTC3824H
Transconductance
FB Input Current V

VC = 0.8V, ∆IVC = ±2µA

= V

FB

(Note 3): LTC3824E/LTC3824I

REF

LTC3824MP/LTC3824H

High IVC = 0 1.6 V

V

C

l
l

0.792

0.788

0.788

0.8 0.808

0.812

0.816

220 260 370 µmho

l
l

10
10

30
60

V
V
V

nA
nA

3824fg

2

LTC3824

elecTrical characTerisTics

The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VCC = 12V, R
outputs, unless otherwise specified.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Low IVC = 0 0.35 0.5 V

V

C

Source Current VVC = 0.5V to 1.3V, VFB = V

V

C

Sink Current VVC = 0.7V to 1.3V, VFB = V

V

C

Threshold for Switching Off V

V

C

Soft-Start Current I

Burst Mode Threshold VCC ≤ 60V, VC Rising, SYNC/MODE Open 0.84 V

V

C

Burst Mode Threshold Hysteresis VCC ≤ 60V 0.04 V

V

C

SS

SENSE Voltage at Burst Mode Operation (V

SYNC/MODE

VSS = 0.1V to 1.5V

CC–VSENSE

= 0V (Note 4)

) at 30% Duty Cycle

70% Duty Cycle
Current Limit Threshold (V

CC–VSENSE

) VCC ≤ 60V: LTC3824E/LTC3824I

LTC3824MP/LTC3824H
FB Overvoltage Threshold V
Sense Input Current V

= 1.6V 8 %

C

= V

SENSE

CC

Oscillator

Switching Frequency R

= 392k: LTC3824E/LTC3824I

SET

LTC3824MP/LTC3824H

= 200k

R

SET

Synchronization Pulse Threshold

Rising Edge V

SYNC

on SYNC Pin
Synchronization Frequency Range R

V

RSET

= 392k

SET

R

= 200k

SET

R

= 392k 1.2 V

SET

Minimum On-Time (Measured at GATE Pin) CCM Operation (Note 5) 350 ns
Switching Frequency Foldback V

= 0.3V

FB

Gate Driver

GATE Bias Voltage (V

) 9V ≤ VCC ≤ 60V, I

CC–VCAP

GATE

LTC3824MP/LTC3824H

GATE Bias Voltage (V

GATE High Voltage (V

–GND) 4V ≤ VCC ≤ 8V, I

CAP

CC–VGATE

) 4V ≤ VCC ≤ 60V, I
GATE Peak Source Current C
GATE Low Voltage (V

GATE–VCAP

) 8V ≤ VCC ≤ 60V, I

GATE Peak Sink Current C

= 12V, I

V

CC

6V ≤ V

CC

= 10nF 2.5 A

GATE

4V ≤ V

CC

= 10nF 2.5 A

GATE

GATE

≤ 8V, I

< 8V, I

= 15mA

= 10mA

GATE

= 15mA

GATE

GATE

GATE

= 10mA

GATE

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 LTC3824 is tested under pulsed load conditions such that
T

≈ TA. The LTC3824E is guaranteed to meet performance specifications

J

from 0°C to 85°C operating 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 LTC3824I is guaranteed over the –40°C to 125°C operating junction
temperature range. The LTC3824H is guaranteed over the –40°C to 150°C
operating junction temperature range. The LTC3824MP is guaranteed

–100mV (V

REF

+100mV (V

REF

= 0V) 15 µA

SYNC

= 0V) 15 µA

SYNC

= 10mA: LTC3824E/LTC3824I

= –15mA 0.5 0.8 V

= 15mA

and tested over the full –55°C to 150°C operating junction temperature
range. High junction temperatures degrade operating lifetimes; operating
lifetime is derated for junction temperatures greater than 125°C. Note that
the maximum ambient temperature consistent with these specifications
is determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance and other environmental
factors. The junction temperature (T
temperature (T

, in °C) and power dissipation (PD, in Watts) according to

A

the formula:
T

= TA + (PD • θJA)

J

where θ

(in °C/W) is the package junction to ambient thermal

JA

impedance.

= 392k, C

SET

= 0.1µF. No load on any

CAP

l

3

l

2.5

5 7.5

0.4 V

8

30
20

l
l

80 75100

100

120
120

0.1 2 µA

l

170

l

170

l

320 400 460 kHz

200
200

230
240

1.3 V

l

230

l

460

l

35 50 75 kHz

l

7.0

l

6.8

l

6.8 V

0.2 0.85 1.5

l

7.9

7.9

0.1

300
600

8.8

8.9

2.8

0.5 V

0.05

, in °C) is calculated from the ambient

J

µA
µA

mV
mV

mV
mV

kHz
kHz

kHz
kHz

V
V

V
V

V

3824fg

3

LTC3824

FREQUENCY (kHz)

700

elecTrical characTerisTics

Note 3: This parameter is tested in a feedback loop that servos VFB to the
reference voltage with the V

Note 4: This specification represents the maximum voltage on V
switching (GATE pin) is guaranteed to be off. The nominal value of V

pin forced to 1V.

C

where

C

C

Note 5: The LTC3824 typically enters Burst Mode operation when the load
is less than one third the current limit. If minimum on-time is violated,
cycle skipping may occur at higher current levels.

where switching turns off is 0.7V.

Typical perForMance characTerisTics

(V)

CAP

-V

CC

V

8.5

8.4

8.3

8.2

8.1

8.0

7.9

7.8

7.7

7.6

(VCC-V

0 10

) vs I

CAP

20 30 40

I

GATE

GATE

at V

(mA)

DRIVE

Low

50

3824 G01

(mA)

CC

I

ICC vs V

3

2

1

0

0

CC

20 30 40

10

VFB = 0.75V

VFB = 0.85V

VCC (V)

TA = 25°C unless otherwise noted.

Switching Frequency Change

50 60

3824 G02

vs VCC at R

3

2

1

0

–1

ΔFREQUENCY (kHz)

–2

–3

0

20 30 40

10

SET

= 392kΩ

VCC (V)

50 60

3824 G03

0.4

0.2

(mV)

REF

ΔV

–0.2

–0.4

Change vs V

V

REF

0

0

10 20 30 40

CC

VCC (V)

50 60

3824 G04

Switching Frequency vs R

600

500

400

300

200

100

100

200 300

R

(kΩ)

SET

SET

400

3824 G05

(mV)

REF

∆V

–1

–2

∆V

5

4

3

2

1

0

–75 –50

REF

vs Temperature

–25 0 25 50

DIE TEMPERATURE (°C)

75 100 150125

3824 G06

4

3824fg

LTC3824

Typical perForMance characTerisTics

Burst Mode Disabled at
I

V

OUT

10mV/DIV

INDUCTOR

CURRENT

1A/DIV

V

OUT

50mV/DIV

= 200mA, V

LOAD

I

= 200mA

LOAD

Burst Mode Operation V

V

=12V, V

IN

OUT

= 5V, I

OUT

4µs/DIV

LOAD

= 5V

OUT

= 200mA

V

50mV/DIV

INDUCTOR

CURRENT

1A/DIV

3824 G07

= 5V

OUTPUT VOLTAGE

AC COUPLED

100mV/DIV

TA = 25°C unless otherwise noted.

Burst Mode Operation V

V

OUT

=12V, V

IN

OUT

= 3V, I

20µs/DIV

LOAD

OUT

= 200mA

Load Current Step Response

= 3V

3824 G08

INDUCTOR

CURRENT

1A/DIV

50µs/DIV

3824 G09

INDUCTOR

CURRENT

2A/DIV

100µs/DIV

3824 G10

3824fg

5