Analog Devices ADP3182 Datasheet

Adjustable Output 1-/2-/3-Phase

FEATURES

Selectable 1-, 2-, or 3-phase operation at up to 1 MHz per

phase
±2% worst-case differential sensing error over temperature
Externally adjustable 0.8 V to >5 V output from a 12 V supply
Logic-level PWM outputs for interface to external high

power drivers
Active current balancing between all output phases
Built-in power good/crowbar functions
Programmable short-circuit protection with programmable

latch-off delay

APPLICATIONS

Auxiliary supplies
DDR memory supplies
Point-of-load modules

FUNCTIONAL BLOCK DIAGRAM

RAMPADJ

9

OSCILLATOR

CURRENT

BALANCING

CIRCUIT

EN

GND

PWRGD

ILIMIT

DELAY

COMP

6

14

5

10

EN

7

4

SHUTDOWN

950mV

FB

650mV

VCC

1

UVLO

& BIAS

DELAY

SOFT

START

RT

8

CURRENT

LIMIT

CIRCUIT

Synchronous Buck Controller

ADP3182

GENERAL DESCRIPTION

The ADP3182 is a highly efficient multiphase, synchronous,
buck-switching regulator controller optimized for converting a
12 V main supply into a high current, low voltage supply for use
in point-of-load (POL) applications. It uses a multimode PWM
architecture to drive the logic-level outputs at a programmable
switching frequency that can be optimized for VR size and
efficiency. The phase relationship of the output signals can be
programmed to provide 1-, 2-, or 3-phase operation, allowing
for the construction of up to three complementary buck­switching stages. The ADP3182 also provides accurate and
reliable short-circuit protection and adjustable current limiting.

ADP3182 is specified over the commercial temperature range of
0°C to +85°C and is available in a 20-lead QSOP package.

ENSET

20

19

18

17
16
15

12

11

13

3

PWM1

PWM2

PWM3

SW1
SW2
SW3
CSSUM

CSREF
CSCOMP

FB

CMP

CMP

1.05V

FB

RESET

RESET

CMP

RESET

CROWBAR CURRENT

2 / 3-PHASE

DRIVER LOGIC

LIMIT

ADP3182

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.
However, no 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. Trademarks and
registered trademarks are the property of their respective owners.

Figure 1.

800mV

REFERENCE

2

FBRTN

04938-001

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

www.analog.com

Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

ADP3182

TABLE OF CONTENTS

Specifications..................................................................................... 3

Output Enable and UVLO ........................................................ 12

Test C ir c uit s ....................................................................................... 5

Absolute Maximum Ratings............................................................ 6

ESD Caution.................................................................................. 6

Pin Configuration and Function Description .............................. 7

Typical Performance Characteristics ............................................. 8

Theory of Operation ........................................................................ 9

Start-Up Sequence ........................................................................ 9

Master Clock Frequency .............................................................. 9

Output Voltage Differential Sensing .......................................... 9

Output Current Sensing .............................................................. 9

Current Control Mode and Thermal Balance ........................ 10

Volt a ge C o ntro l Mod e ................................................................10

Soft Start ......................................................................................10

Current Limit, Short-Circuit, and Latch-off Protection ....... 10

Power Good Monitoring ........................................................... 11

Applications..................................................................................... 14

Setting the Clock Frequency..................................................... 14

Soft Start and Current Limit Latch-Off Delay Time ............. 14

Inductor Selection...................................................................... 14

Output Current Sense................................................................ 15

Output Voltage............................................................................ 16

Power MOSFETs......................................................................... 16

Ramp Resistor Selection............................................................ 17

Current Limit Setpoint .............................................................. 17

Feedback Loop Compensation Design.................................... 17

Input Capacitor Selection and Input Current di/dt............... 18

Inductor DCR Temperature Correction ................................. 18

Layout and Component Placement ......................................... 19

Outline Dimensions ....................................................................... 20

Ordering Guide .......................................................................... 20

Output Crowbar .........................................................................11

REVISION HISTORY

10/04—Revision 0: Initial Version

Rev. 0 | Page 2 of 20

ADP3182

SPECIFICATIONS

VCC = 12 V, FBRTN = GND, TA = 0°C to 85°C, unless otherwise noted.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

OSCILLATOR

Frequency Range
Frequency Variation f

Output Voltage V
RAMPADJ Output Voltage V

RAMPADJ Input Current Range I

2

f

OSC

PHASE

RT

RAMPADJ

RAMPADJ

0.25 3 MHz
TA = 25°C, RT = 348 kΩ, 3-phase

= 25°C, RT = 174 kΩ, 3-phase

T

A

= 25°C, RT = 100 kΩ, 3-phase

T

A

RT = 100 kΩ to GND
RAMPADJ − FB −50 +50 mV
0 100

VOLTAGE ERROR AMPLIFIER

Output Voltage Range2 V
Accuracy V
Line Regulation

Input Bias Current I
FBRTN Current I
Output Current I
Gain Bandwidth Product GBW

COMP

FB

∆V

FB

FBRTN

O(ERR)

FB

(ERR)

Slew Rate C

0.7 3.1 V
Referenced to FBRTN 784 800 816 mV
VCC = 10 V to 14 V 0.05 %

FB = 800 mV −4 +4
100 140
FB forced to V
COMP = FB 20 MHz

= 10 pF 25

COMP

CURRENT SENSE AMPLIFIER

Offset Voltage V
Input Bias Current I
Gain Bandwidth Product GBW

OS(CSA)

BIAS(CSSUM)

(CSA)

Slew Rate C

CSSUM − CSREF, Figure 2 −5.5 +5.5 mV

−50 +50 nA
10 MHz

= 10 pF 10

CSCOMP

Input Common-Mode Range CSSUM and CSREF 0 VCC − 2.5 V
Output Voltage Range 0.05 VCC − 2.5 V
Output Current I

CSCOMP

500

CURRENT BALANCE CIRCUIT

Common-Mode Range V
Input Resistance R

Input Current I
Input Current Matching

SW(X)CM

SW(X)

SW(X)

∆I

SW(X)

−600 +200 mV
SW(X) = 0 V 20 30 40

SW(X) = 0 V 4 7 10
SW(X) = 0 V −7 +7 %

CURRENT LIMIT COMPARATOR

Output Voltage
Normal Mode V

In Shutdown Mode V
Output Current, Normal Mode I

ILIMIT(NM)

ILIMIT(SD)

ILIMIT(NM)

EN > 2 V, R
EN < 0.8 V, I
EN > 2 V, R

Maximum Output Current2 60
Current Limit Threshold Voltage V
Current Limit Setting Ratio VCL/I
DELAY Normal Mode Voltage V
DELAY Overcurrent Threshold V
Latch-Off Delay Time t

CL

DELAY(NM)

DELAY(OC)

DELAY

V

R
R
R

CSREF

ILIMIT

DELAY

DELAY

DELAY

− V

CSCOMP

= 250 kΩ
= 250 kΩ
= 250 kΩ, C

SOFT START

Output Current, Soft Start Mode I
Soft Start Delay Time t

DELAY(SS)

DELAY(SS)

During start-up, DELAY < 2.4 V 15 20 25

R

= 250 kΩ, C

DELAY

1

155 200 245 kHz
400 kHz
600 kHz

1.9 2.0 2.1 V

− 3% 500

OUT

= 250 kΩ

ILIMIT

ILIMIT

= 250 kΩ

ILIMIT

, R

= −100 µA

= 250 kΩ

ILIMIT

2.9 3 3.1 V
400 mV
12

105 125 145 mV

10.4

2.9 3 3.1 V

1.7 1.8 1.9 V

DELAY

DELAY

= 12 nF

= 12 nF

1.5 ms

500

µA

µA
µA
µA

V/µs

V/µs

µA

kΩ

µA

µA
µA

mV/µA

µA
µs

Rev. 0 | Page 3 of 20

ADP3182

Parameter Symbol Conditions Min Typ Max Unit

ENABLE INPUT

Input Low Voltage V

Input High Voltage V

Input Current I

IL(EN)

IH(EN)

IN(EN)

POWER GOOD COMPARATOR

Undervoltage Threshold V

Overvoltage Threshold V

Output Low Voltage V

PWRGD(UV)

PWRGD(OV)

OL(PWRGD)IPWRGD(SINK)

Power Good Delay Time 200 ns

Crowbar Trip Point V

CROWBAR

Crowbar Reset Point Relative to FBRTN 550 650 750 mV

Crowbar Delay Time t

CROWBAR

PWM OUTPUTS

Output Low Voltage V

Output High Voltage V

OL(PWM)

OH(PWM)

SUPPLY

DC Supply Current 5 10 mA

UVLO Threshold Voltage V

UVLO

UVLO Hysteresis 0.7 0.9 1.1 V

1

All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC).

2

Guaranteed by design or bench characterization, not tested in production.

0.8 V

2.0 V

−1 +1

µA

Relative to FBRTN 600 660 720 mV
Relative to FBRTN 880 940 1000 mV

= 4 mA 225 400 mV

Relative to FBRTN 0.975 1.05 1.1 V

Overvoltage to PWM going low 400 ns

I

PWM(SINK)

I

PWM(SOURCE)

= −400 µA

= 400 µA

160 500 mV

4.0 5 V

VCC rising 6.5 6.9 7.3 V

Rev. 0 | Page 4 of 20

ADP3182

TEST CIRCUITS

ADP3182

1

100nF

V

CSCOMP

13

CSSUM

12

CSREF

11

14

GND

CC

CSCOMP –0.8V

VOS =

40

04938-002

OS

12V

39kΩ

1kΩ

0.8V

Figure 2. Current Sense Amplifier V

Rev. 0 | Page 5 of 20

ADP3182

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

VCC −0.3 V to +15 V
FBRTN −0.3 V to +0.3 V
EN, DELAY, ILIMIT, RT,

PWM1 to PWM3, COMP
SW1 to SW3 −5 V to +25 V
All Other Inputs and Outputs −0.3 V to VCC + 0.3 V
Storage Temperature −65°C to +150°C
Operating Ambient Temperature Range 0°C to 85°C
Operating Junction Temperature 125°C

Thermal Impedance (θJA)
Lead Temperature

Soldering (10 s) 300°C

Infrared (15 s) 260°C

−0.3 V to 5.5 V

100°C/W

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and 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. Absolute maximum ratings apply individually
only, not in combination. Unless otherwise specified, all other
voltages are referenced to GND.

Rev. 0 | Page 6 of 20