Analog Devices ADP3161 Datasheet

4-Bit Programmable 2-Phase

a

FEATURES
ADOPT™ Optimal Positioning Technology for Superior

Load Transient Response and Fewest Output

Capacitors
Active Current Balancing Between Both Output Phases
VRM 8.4-Compatible Digitally Programmable 1.3 V to

2.05 V Output

Dual Logic-Level PWM Outputs for Interface to External

High-Power Drivers
Total Output Accuracy ⴞ0.8% Over Temperature
Current-Mode Operation
Short Circuit Protection
Power-Good Output
Overvoltage Protection Crowbar Protects

Microprocessors with No Additional

External Components

APPLICATIONS
Desktop PC Power Supplies for:

Intel Pentium

VRM Modules

®

III Processors

Synchronous Buck Controller

ADP3161

FUNCTIONAL BLOCK DIAGRAM

VCC

CROWBAR

CMP

CMP1

SET

RESET

CMP3

CMP2

CMP

2-PHASE

DRIVER

LOGIC

DAC+24%

DAC–18%

g

m

REF

GND

COMP

CT

UVLO

& BIAS

3.0V

REFERENCE

OSCILLATOR

ADP3161

PWM1

PWM2

PWRGD

CS–

CS+

FB

GENERAL DESCRIPTION

The ADP3161 is a highly efficient dual output synchronous buck
switching regulator controller optimized for converting a 5 V or
12 V main supply into the core supply voltage required by high­performance processors such as Pentium

®

III. The ADP3161
uses an internal 4-bit DAC to read a voltage identification (VID)
code directly from the processor, which is used to set the output
voltage between 1.3 V and 2.05 V. The ADP3161 uses a current
mode PWM architecture to drive two logic-level outputs at a
programmable switching frequency that can be optimized for
VRM size and efficiency. The output signals are 180 degrees out of
phase, allowing for the construction of two complementary buck
switching stages. These two stages share the dc output current
to reduce overall output voltage ripple. An active current bal­ancing function ensures that both phases carry equal portions
of the total load current, even under large transient loads, to
minimize the size of the inductors.

ADOPT is a trademark of Analog Devices Inc.
Pentium is a registered trademark of Intel Corporation

VID

DAC

VID3 VID2 VID1 VID0

The ADP3161 also uses a unique supplemental regulation tech­nique called active voltage positioning to enhance load transient
performance. Active voltage positioning results in a dc/dc con­verter that meets the stringent output voltage specifications for
high-performance processors, with the minimum number of
output capacitors and smallest footprint. Unlike voltage-mode and
standard current-mode architectures, active voltage positioning
adjusts the output voltage as a function of the load current so
that it is always optimally positioned for a system transient. The
ADP3161 also provides accurate and reliable short circuit protec­tion and adjustable current limiting.

The ADP3161 is specified over the commercial temperature
range of 0°C to 70°C and is available in a 16-lead narrow body
SOIC package.

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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 2001

1

ADP3161–SPECIFICATIONS

(VCC = 12 V, I

Parameter Symbol Conditions Min Typ Max Unit

FEEDBACK INPUT

Accuracy V

FB

1.3 V Output TPC 1 1.290 1.3 1.310 V

1.6 V Output TPC 1 1.587 1.6 1.613 V

2.05 V Output TPC 1 2.034 2.05 2.066 V

Line Regulation ∆V
Input Bias Current I

FB

Crowbar Trip Point V

FB

CROWBAR

VCC = 10 V to 14 V 0.05 %

Percent of Nominal Output 114 124 134 %
Crowbar Reset Point Percent of Nominal Output 50 60 70 %
Crowbar Response Time t
FB Low Comparator Threshold V

CROWBAR

FB(LOW)

Overvoltage to PWM Going Low 300 ns

REFERENCE

Output Voltage V
Output Current I

REF

REF

VID INPUTS

Input Low Voltage V
Input High Voltage V
Input Current I
Pull-Up Resistance R

IL(VID)

IH(VID)

VID

VID

VID(X) = 0 V 180 250 µA

Internal Pull-Up Voltage 4.5 5.0 5.5 V

OSCILLATOR

Maximum Frequency
Frequency Variation ∆f
CT Charge Current I

2

f

CT(MAX)

CT

CT

TA = 25°C, CT = 91 pF 430 500 570 kHz

TA = 25°C, VFB in Regulation 130 150 170 µA

TA = 25°C, VFB = 0 V 263646 µA

ERROR AMPLIFIER

Output Resistance R
Transconductance g
Output Current I
Maximum Output Voltage V
Output Disable Threshold V
–3 dB Bandwidth BW

O(ERR)

m(ERR)

O(ERR)

COMP(MAX)

COMP(OFF)

ERR

VFB = 0 V 1 mA

FB Forced to V

COMP = Open 500 kHz

CURRENT SENSE

Threshold Voltage V

CS(TH)

CS+ = VCC, 69 79 89 mV

FB Forced to V

0.8 V ≤ COMP ≤ 1 V 0 15 mV

FB ≤ 375 mV 37 47 58 mV

1 V ≤ V

COMP

CS+ = CS– = VCC 0.5 5 µA

CS+ – (CS–) ≥ 89 mV 50 ns

∆V

COMP

/∆V

CS

Input Bias Current I
Response Time t

V

CS(FOLD)

n

i

, I

CS+

CS

CS–

to PWM Going Low

POWER GOOD COMPARATOR

Undervoltage Threshold V
Overvoltage Threshold V
Output Voltage Low V

PWRGD(UV)

PWRGD(OV)

OL(PWRGD)IPWRGD(SINK)

Percent of Nominal Output 76 82 88 %

Percent of Nominal Output 114 124 134 %

Response Time FB Going High 2 µs

FB Going Low 200 ns

PWM OUTPUTS

Output Voltage Low V
Output Voltage High V
Output Current I
Duty Cycle Limit

2

OL(PWM)

OH(PWM)

PWM

DC Per Phase, Relative to f

I

PWM(SINK)

I

PWM(SOURCE)

= 150 ␮A, TA = 0ⴗC to 70ⴗC, unless otherwise noted.)

REF

550 nA

375 425 500 mV

2.952 3.0 3.048 V
300 µA

0.6 V

2.2 V

20 28 kΩ

2000 kHz

200 kΩ

2.0 2.2 2.45 mmho

– 3% 3.0 V

OUT

560 720 800 mV

– 3%

OUT

≤ 3 V 25 V/V

= 100 µA 30 200 mV

= 400 µA 100 500 mV

= 400 µA 4.5 5.0 5.5 V

0.4 1 mA

CT

50 %

–2– REV. 0

ADP3161

WARNING!

ESD SENSITIVE DEVICE

Parameter Symbol Conditions Min Typ Max Unit

SUPPLY

DC Supply Current

Normal Mode I
UVLO Mode I

UVLO Threshold Voltage V

CC

CC(UVLO)

UVLO

VCC ≤ V

, VCC Rising 220 400 µA

UVLO

UVLO Hysteresis 0.1 0.4 0.6 V

NOTES

1

All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.

2

Guaranteed by design, not tested in production.

Specifications subject to change without notice.

3.8 5.5 mA

5.9 6.4 6.9 V

ABSOLUTE MAXIMUM RATINGS*

VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +15 V

CS+, CS– . . . . . . . . . . . . . . . . . . . . . . –0.3 V to VCC + 0.3 V

All Other Inputs and Outputs . . . . . . . . . . . . –0.3 V to +10 V

Operating Ambient Temperature Range . . . . . . . 0°C to 70°C

Operating Junction Temperature . . . . . . . . . . . . . . . . . . 125°C

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

θ

JA

Two-Layer Board . . . . . . . . . . . . . . . . . . . . . . . . . . 125°C/W

Four-Layer Board . . . . . . . . . . . . . . . . . . . . . . . . . . 81°C/W

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

Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 215°C

Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C

*This is a stress rating only; operation beyond these limits can cause the device to

be permanently damaged. Unless otherwise specified, all voltages are referenced
to GND.

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

ADP3161JR 0°C to 70°C Narrow Body SOIC R-16A (SO-16)

PIN CONFIGURATION

R-16A

1

NC

VID3

2

3

VID2

4

VID1

VID0

5

COMP

6

7

FB

8

CT

NC = NO CONNECT

ADP3161

TOP VIEW

(Not to Scale)

16

15

14

13

12

11

10

9

VCC

REF

CS–

PWM1

PWM2

CS+

PWRGD

GND

PIN FUNCTION DESCRIPTIONS

Pin
No. Name Function

1 NC No Connect.
2–5 VID3– Voltage Identification DAC Inputs.

VID0 These pins are pulled up to an internal refer-

ence, providing a Logic 1 if left open. The
DAC output programs the FB regulation
voltage from 1.3 V to 2.05 V.

6 COMP Error Amplifier Output and Compensation

Point. The voltage at this output programs
the output current control level between
CS+ and CS–.

7 FB Feedback Input. Error amplifier input for

remote sensing of the output voltage.

8 CT External capacitor CT connection to ground

sets the frequency of the device.

9 GND Ground. All internal signals of the ADP3161

are referenced to this ground.

10 PWRGD Open drain output that signals when the output

voltage is in the proper operating range.

11 CS+ Current Sense Positive Node. Positive input

for the current comparator. The output
current is sensed as a voltage at this pin with

respect to CS–.
12 PWM2 Logic-level output for the phase 2 driver.
13 PWM1 Logic-level output for the phase 1 driver.
14 CS– Current Sense Negative Node. Negative

input for the current comparator.
15 REF 3.0 V Reference Output.
16 VCC Supply Voltage for the ADP3161.

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 the ADP3161 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.

–3–REV. 0

ADP3161

4-BIT CODE

100

100nF

–Typical Performance Characteristics

ADP3161

16

1

2

3

4

5

6

7

8

NC

VID3

VID2

VID1

VID0

COMP

FB

CT

VCC

REF

CS–

PWM1

PWM2

CS+

PWRGD

GND

15

14

13

12

11

10

9

+

1 F

100nF

NC = NO CONNECT

12V

4.10

4.05

4.00

3.95

V

FB

AD820

1.2V

TPC 1. Closed-Loop Output Voltage Accuracy Test Circuit

10000

1000

OSCILLATOR FREQUENCY – kHz

100

0

100

200 300 400 500

CT CAPACITOR – pF

TPC 2. Oscillator Frequency vs. Timing Capacitor

SUPPLY CURRENT – mA

3.90

3.85
250 500 750 1250 1500 1750

0 2000

OSCILLATOR FREQUENCY – kHz

1000

TPC 3. Supply Current vs. Oscillator Frequency

30

25

20

15

10

NUMBER OF PARTS – %

5

0
–0.5 0.5

OUTPUT ACCURACY – % OF NOMINAL

0

TA = 25⬚C

V

OUT

= 1.6V

TPC 4. Output Accuracy Distribution

5V

OR

12V

VID INPUTS

12V

ADP3161

2-PHASE

SYNCHRONOUS

BUCK

CONTROLLER

5V

I

L1

PWM1

PWM2

ADP3412

SYNCHRONOUS

DRIVER

5V

ADP3412

SYNCHRONOUS

DRIVER

5V OR 12V

OUT

+

I

L2

TPC 5. 2-Phase CPU Supply System Level Block Diagram

–4– REV. 0

I

OUT

I

L2

PWM2

PWM1

I

L1