ANALOG DEVICES ADP2441 Service Manual

Step-Down DC-to-DC Regulator

ADP2441

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

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FB

COMP

EN

PGOOD

FREQ

SS/TRK

PGND

VIN

SW

BST

AGND

VCC

ADP2441

C4

C3

C

BST

C

IN

C

OUT

R

TOP

R

FREQ

R

COMP

C

COMP

R

BOTTOM

V

OUT

10581-001

V

OUT

V

IN

0

20

40

60

80

100

10

30

50

70

90

0.02 0.2 1

EFFICIENCY (%)

LOAD (A)

V

OUT

= 3.3V

10581-002

V

OUT

= 5V

V

OUT

= 12V

V

IN

= 24V

f

SW

= 300kHz

Data Sheet

FEATURES

Wide input voltage range of 4.5 V to 36 V Low minimum on time of 50 ns Maximum load current of 1 A High efficiency of up to 94% Adjustable output down to 0.6 V ±1% output voltage accuracy Adjustable switching frequency of 300 kHz to 1 MHz Pulse skip mode at light load for power saving Precision enable input pin Open-drain power good External soft start with tracking Overcurrent-limit protection Shutdown current of less than 15 µA UVLO and thermal shutdown 12-lead, 3 mm × 3 mm LFCSP package

APPLICAT ION S

Point of load applications Distributed power systems Industrial control supplies Standard rail conversion to 24 V/12 V/5 V/3.3 V

36 V,1 A, Synchronous,

TYPICAL CIRCUIT CONFIGURATION

Figure 1.

GENERAL DESCRIPTION

The ADP2441 is a constant frequency, current mode control, synchronous, step-down dc-to-dc regulator that is capable of driving loads up to 1 A with excellent line and load regulation characteristics. The ADP2441 operates with a wide input voltage range of 4.5 V to 36 V, which makes it ideal for regulating power from a wide variety of sources. In addition, the ADP2441 has very low minimum on time (50 ns) and is, therefore, suitable for applications requiring a very high step-down ratio.

The output voltage can be adjusted from 0.6 V to 0.9 V × V High efficiency is obtained with integrated low resistance N-channel MOSFETs for both high-side and low-side devices.

The switching frequency is adjustable from 300 kHz to 1 MHz with an external resistor. The ADP2441 also has an accurate power-good (PGOOD) open-drain output signal.

At light load conditions, the regulator operates in pulse skip mode by skipping pulses and reducing switching losses to improve energy efficiency. In addition, at medium to heavy load conditions, the regulator operates in fixed frequency pulse-width modulation (PWM) mode to reduce electromagnetic interference (EMI).

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

.

IN

The ADP2441 uses hiccup mode to protect the IC from short circuits or from overcurrent conditions on the output. The external programmable soft start limits inrush current during startup for a wide variety of load capacitances. Other key features include tracking, input undervoltage lockout (UVLO), thermal shutdown (TSD), and precision enable (EN), which can also be used as a logic level shutdown input.

The ADP2441 is available in a 3 mm × 3 mm, 12-lead LFCSP package and is rated for a junction temperature range of −40°C to +125°C.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700

Figure 2. Efficiency vs. Load Current, VIN = 24 V

www.analog.com

ADP2441 Data Sheet

REVISION HISTORY

6/12—Revision 0: Initial Version

Rev. 0 | Page 2 of 32

Data Sheet ADP2441

Hysteresis

200 mV

Feedback Regulation Voltage

VFB

TJ = −40°C to +85°C

0.594

0.6

0.606

V

Leakage Current

I

VEN = AGND

1 25

μA

Peak Current Limit

ICL 1.4

1.6

1.8

A

Frequency Set Accuracy

FREQ pin = 308 kΩ

270

300

330

kHz

Hysteresis

V

100 mV

SPECIFICATIONS

VIN = 4.5 V to 36 V, TJ = −40°C to +125°C, unless otherwise noted.

Table 1.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

POWER SUPPLY

Input Voltage Range VIN 4.5 36 V Supply Current I Shutdown Current I UVLO

Threshold V

INTERNAL REGULATOR

Regulator Output Voltage VCC VIN = 5 V to 36 V 5 5.5 V

OUTPUT

Output Voltage Range V Maximum Output Current I

TJ = −40°C to +125°C 0.591 0.6 0.609 V Line Regulation 0.005 %/V Load Regulation 0.05 %/A

ERROR AMPLIFIER

Feedback Bias Current I Transconductance gm I Open-Loop Voltage Gain1 A

MOSFETS

High-Side Switch On Resistance2 R Low-Side Switch On Resistance2 R

Minimum On Time3 t Minimum Off Time

4

CURRENT SENSE

Current Sense Amplifier Gain GCS 1.6 2 2.4 A/V Hiccup Time fSW = 300 kHz to1 MHz 6 ms Number Of Cumulative Current-Limit Cycles

to Go into Hiccup Mode

VEN = 1.5 V not switching 1.7 2.2 mA

VIN

VEN = AGND 10 15 µA

SHDN

VIN falling 3.8 4 4.2 V

UVLO

0.6 0.9 × VIN V

OUT

1 A

OUT

VFB = 0.6 V 50 200 nA

FB_BIAS

= ±20 µA 200 250 300 µA/V

COMP

65 dB

VOL

BST − SW = 5 V 170 270 mΩ

DS_H(ON)

VCC = 5 V 120 180 mΩ

DS_L(ON)

LKG

All switching frequencies 50 65 ns

ON_MIN

t

165 175 ns

OFF_MIN

8 Events

FREQUENCY

Switching Frequency Range fSW 300 1000 kHz

FREQ pin = 92.5 kΩ 900 1000 1100 kHz

SOFT START

Soft Start Current ISS VSS = 0 V 0.9 1 1.2 µA

PRECISION ENABLE

Input Threshold V

Leakage Current I Thermal Shutdown

Rising TSD 150 °C Hysteresis T

1.15 1.20 1.25 V

EN(RISING)

EN(HYST )

VIN = VEN 0.1 1 µA

IEN_LEAK

25 °C

SD(HYST )

Rev. 0 | Page 3 of 32

ADP2441 Data Sheet

PGOOD Low, FB Falling Threshold5

83

86

89

%

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

POWER GOOD

PGOOD High, FB Rising Threshold5 89 92 95 % PGOOD Low, FB Rising Threshold5 111 115 118 % PGOOD High, FB Falling Threshold5 106 109 112 %

PGOOD

Delay t High Leakage Current I Pull-Down Resistor I

TRK

TRK Input Voltage Range 0 600 mV TRK to FB Offset Voltage TRK = 0 mV to 500 mV 10 mV

1

Guaranteed by design.

2

Measured between VIN and SW pins—includes bond wires and pin resistance.

3

Based on bench characterization. Measured with VIN = 12 V, V

4

Based on bench characterization. Measured with VIN = 15 V, V

5

This threshold is expressed as a percentage of the nominal output voltage.

50 µs

PGOOD

V

PGOOD(SRC)

FB = 0 V 0.5 0.7 kΩ

PGOOD(SNK)

= 1.2 V, load = 1 A, fSW = 1 MHz, and the output in regulation. Measurement does not include dead time.

OUT

= 12 V, load = 1 A, fSW = 600 kHz, and the output in regulation. Measurement does not include dead time.

OUT

= VCC 1 10 µA

PGOOD

Rev. 0 | Page 4 of 32

Data Sheet ADP2441

EN to AGND

−0.3 V to +40 V

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

VIN to PGND −0.3 V to +40 V

SW to PGND −0.3 V to +40 V BST to PGND −0.3 V to +45 V VCC to AGND −0.3 V to +6 V BST to SW −0.3 V to +6 V FREQ, PGOOD, SS/TRK, COMP, FB to AGND −0.3 V to +6 V PGND to AGND ±0.3 V Operating Junction Temperature Range −40°C to +125°C Storage Temperature Range −65°C to +150°C Lead Temperature (Soldering, 10 sec) 260°C

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages, and is based on a 4-layer standard JEDEC board.

Table 3. Thermal Resistance

Package Type θJA θJC Unit

12-Lead LFCSP 40 2.4 °C/W

ESD CAUTION

Rev. 0 | Page 5 of 32

ADP2441 Data Sheet

FB

COMP

NOTES

1. THE EXPOSED PAD SHOULD BE CONNECTED TO THE SYSTEMAGND P LANE AND PGND PLANE.

EN

VIN SW PGND

PGOOD

FREQ

SS/TRK

AGND

VCC

BST

10581-003

9 8 7

1 2 3

4

5

6

12

11

10

TOP

VIEW

ADP2441

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

Figure 3. Pin Configuration, Top View

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1 FB Feedback Regulation Voltage is 0.6 V. Connect this pin to a resistor divider from the output of the dc-to-dc regulator. 2 COMP Error Amplifier Compensation. Connect a resistor and capacitor in series to ground. 3 EN Precision Enable. This features offers ±5% accuracy when using a 1.25 V reference voltage. Pull this pin high to

enable the regulator and low to disable the regulator. 4 PGOOD Active High Power-Good Output. This pin is pulled low when the output is out of regulation. 5 FREQ Switching Frequency. A resistor to AGND sets the switching frequency (see the Setting the Switching Frequency section). 6 SS/TRK Soft Start/Trac king Input. A capacitor to ground is required to program the soft start time, which gradually ramps

up the output. A resistive divider to an external reference is required on this pin to track an external voltage. 7 PGND Power Ground. Connect a decoupling ceramic capacitor as close as possible between the VIN pin and this pin.

Connect this pin directly to the exposed pad. 8 SW Switch. The midpoint for the drain of the low-side N-channel power MOSFET switch and the source for the high-side

N-channel power MOSFET switch. 9 VIN Power Supply Input. Connect this pin to the input power source, and connect a bypass ceramic capacitor directly

from this pin to PGND, as close as possible to the IC. The operation voltage is 4.5 V to 36 V. 10 BST Boost. Connect a 10 nF ceramic capacitor between the BST and SW pins as close to the IC as possible to form a

floating supply for the high-side N-Channel power MOSFET driver. This capacitor is needed to drive the gate of the

N-channel power MOSFET above the supply voltage. 11 VCC Output of the Internal Low Dropout Regulator. This pin supplies power for the internal controller and driver circuitry.

Connect a 1 µF ceramic capacitor between VCC and AGND and a 1 µF ceramic capacitor between VCC and PGND.

The VCC output is active when the EN pin voltage is more than 0.7 V. 12 AGND Analog Ground. This pin is the internal ground for the control functions. Connect this pin directly to the exposed pad. EP Exposed Thermal Pad. The exposed pad should be connected to AGND and PGND.

Rev. 0 | Page 6 of 32

Data Sheet ADP2441

0

20

40

60

80

100

10

30

50

70

90

0.01 0.1 LOAD (A)

1

EFFICIENCY (%)

V

IN

= 5V

V

IN

= 24V

V

OUT

= 3.3V

f

SW

= 300kHz

COILCRAF T MSS1038

VIN= 12V

10581-004

0

20

40

60

80

100

10

30

50

70

90

0.01 0.1 1

EFFICIENCY (%)

LOAD (A)

VIN = 12V

10581-006

VIN= 24V

VIN= 36V

V

OUT

= 5V

f

SW

= 300kHz

COILCRAF T MSS1038

0

20

40

60

80

100

10

30

50

70

90

0.01 0.1 1

EFFICIENCY (%)

LOAD (A)

VIN = 24V

10581-008

VIN= 36V

V

OUT

= 12V

f

SW

= 300kHz

COILCRAF T MSS1038

0

20

40

60

80

100

10

30

50

70

90

0.01 0.1 1

EFFICIENCY (%)

LOAD (A)

V

IN

= 5V

VIN= 12V

VIN= 24V

V

OUT

= 3.3V

f

SW

= 700kHz

COILCRAF T MSS1038

10581-005

0

20

40

60

80

100

10

30

50

70

90

0.01 0.1 1

EFFICIENCY (%)

LOAD (A)

VIN = 12V

10581-007

VIN= 36V

V

OUT

= 5V

f

SW

= 700kHz

COILCRAF T MSS1038

VIN= 24V

0

20

40

60

80

100

10

30

50

70

90

0.01 0.1 1

EFFICIENCY (%)

LOAD (A)

10581-009

V

OUT

= 12V

f

SW

= 600kHz

COILCRAF T MSS1038

VIN = 24V

VIN= 36V

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 4. Efficiency vs. Load Current,

V

= 3.3 V, fSW = 300 kHz

OUT

Figure 5. Efficiency vs. Load Current,

V

= 5 V, fSW = 300 kHz

OUT

Figure 7. Efficiency vs. Load Current,

V

= 3.3 V, fSW = 700 kHz

OUT

Figure 8. Efficiency vs. Load Current,

V

= 5 V, fSW = 700 kHz

OUT

Figure 6. Efficiency vs. Load Current,

V

= 12 V, fSW = 300 kHz

OUT

Figure 9. Efficiency vs. Load Current,

V

= 12 V, fSW = 600 kHz

OUT

Rev. 0 | Page 7 of 32

ADP2441 Data Sheet

–0.5

–0.4

–0.3

–0.2

–0.1

0

0.1

0.2

0.3

0.4

0.5

0 0.2 0.4 0.6 0.8 1.0

V

OUT

ERROR (%)

LOAD (A)

V

IN

= 12V

V

IN

= 24V

V

IN

= 36V

V

OUT

= 5V

f

SW

= 700kHz

10581-010

1.0

0 0.2 0.4 0.6 0.8 1.0

V

OUT

ERROR (%)

LOAD (A)

T

A

= –40°C

T

A

= +25°C

T

A

= +125°C

10581-011

VIN= 24V V

OUT

= 5V

f

SW

= 700kHz

–0.5

–0.4

–0.3

–0.2

–0.1

0

0.1

0.2

0.3

0.4

0.5

7 12 17 22 27 32 37

V

OUT

ERROR (%)

VIN (V)

LOAD = 500mA

LOAD = 1A

10581-012

VIN= 24V V

OUT

= 5V

f

SW

= 700kHz

0

50

100

150

200

250

300

350

400

5 10 15 20 25 30 35 40

P

SKIP

THRESHOL D LOAD CURRENT (mA)

VIN (V)

f

SW

= 300kHz

f

SW

= 700kHz

V

OUT

= 3.3V

10581-013

0

50

100

150

200

250

300

10 15 20 25 30 35 40

P

SKIP

THRESHOL D LOAD CURRENT (mA)

VIN (V)

f

SW

=

700kHz

10581-014

V

OUT

= 5V

f

SW

=

300kHz

0

50

100

150

200

250

300

15 20 25 30 35 40

P

SKIP

THRESHOL D LOAD CURRENT (mA)

VIN (V)

f

SW

=

300kHz

f

SW

=

600kHz

10581-015

V

OUT

= 12V

Figure 10. Load Regulation for Different Supplies

0.8

0.6

0.4

0.2

0

–0.2

–0.4

–0.6

–0.8

–1.0

Figure 13. Pulse Skip Threshold, V

OUT

= 3.3 V

Figure 11. Load Regulation for Different Temperatures

Figure 12. Line Regulation, V

OUT

= 5 V for Different Loads

Rev. 0 | Page 8 of 32

Figure 14. Pulse Skip Threshold, V

Figure 15. Pulse Skip Threshold, V

OUT

= 5 V

= 12 V

Data Sheet ADP2441

0

2

4

8

6

10

12

–50 0 50 100 150

SHUTDOWN CURE NT (µA)

TEMPERATURE (°C)

V

IN

= 36V

V

IN

= 4.5V

10581-017

UVLO THRE S HOLD (V)

TEMPERATURE (°C)

10581-018

3.9

4.0

4.1

4.2

4.3

4.4

4.5

–50 –25 0 25 50 75 100 125

UVLO, RISING V

IN

UVLO, FALLING V

IN

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

FB (V)

TRACK (V)

10581-118

0.05

0.25

0.45

0.65

0.85

1.05

1.25

1.45

1.65

1.85

2.05

2.25

–50 –30 –10 10 30 50 70 90 110 130 150

SUPPLY CURRENT ( mA)

TEMPERATURE (°C)

V

IN

= 36V

V

IN

= 24V

V

IN

= 12V

V

IN

= 4.5V

10581-016

1.04

1.06

1.08

1.10

1.12

1.14

1.16

1.18

1.20

1.22

1.24

–50 –30 –10 10 30 50 70 90 110 130 150

ENABLE VOLTAGE (V)

TEMPERATURE (°C)

ENABLE RISING THRESHOLD

ENABLE FALLING THRESHOLD

10581-019

60

70

80

90

100

110

120

130

–50 –30 –10 10 30 50 70 90 110 130 150

PGOOD THRESHOLD (%)

TEMPERATURE (°C)

P

GOOD

RISE, F B INCREASING

P

GOOD

FALL, FB INCREASING

P

GOOD

RISE, F B DE CRE AS ING

P

GOOD

FALL, FB DECREASING

10581-021

Figure 16. Shutdown Current vs. Temperature

Figure 17. UVLO Threshold vs. Temperature

Figure 19. Supply Current vs. Temperature

Figure 20. Enable Threshold vs. Temperature

Figure 18. Tracking Range

Figure 21. PGOOD Threshold vs. Temperature

Rev. 0 | Page 9 of 32

ADP2441 Data Sheet

0

200

400

600

800

1000

1200

0 5 10 15 20 25 30 35 40

SWITCHING FREQUE NCY (kHz)

VIN (V)

f

SW

= 300kHz

f

SW

= 1MHz

f

SW

= 700kHz

10581-022

0

25

50

75

100

125

150

175

200

–50 –30 –10 10 30 50 70 90 110 130 150

ON TIMEAND OFF TIME (ns)

TEMPERATURE (°C)

MINIMUM ON

MINIMUM OFF

10581-024

100

120

140

160

180

200

220

240

260

–50 –25 0 25 50 75 100 125 150

HIGH-SI DE R

DS(ON)

(mΩ)

TEMPERATURE (°C)

10581-027

200

300

400

500

600

700

800

900

1000

1100

1200

–50 –30 –10 10 30 50 70 90 110 130 150

FREQUENCY (kHz)

TEMPERATURE (°C)

f

SW

= 300kHz

f

SW

= 1MHz

f

SW

= 700kHz

10581-023

1.50

1.52

1.54

1.56

1.58

1.60

1.62

1.64

1.66

1.68

1.70

1.72

1.74

1.76

1.78

1.80

–50 0 50 100 150

CURRENT (A)

TEMPERATURE (°C)

V

IN

= 36V

VIN = 4.5V

10581-126

0

20

40

60

80

100

120

140

160

180

–50 –30 –10 10 30 50 70 90 110 130 150

LOW-SIDE R

DS(ON)

(mΩ)

TEMPERATURE (°C)

10581-026

Figure 22. Switching Frequency vs. Supply

Figure 23. Minimum On Time and Minimum Off Time vs. Temperature

Figure 25. Switching Frequency vs. Temperature

Figure 26. Current Limit vs. Temperature

Figure 24. High-Side R

vs. Temperature

DS(ON)

Figure 27. Low-Side R

vs. Temperature

DS(ON)

Rev. 0 | Page 10 of 32

ANALOG DEVICES ADP2441 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICAT ION S

TYPICAL CIRCUIT CONFIGURATION

GENERAL DESCRIPTION

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

TYPICAL PERFORMANCE CHARACTERISTICS