MAXIM MAX1917 Technical data

General Description

The MAX1917 provides a complete power-manage­ment solution for DDR memory. It contains a synchro­nous buck controller and an amplifier to generate
1/2V

DDR

voltage for VTT and VTTR. The VTT and VTTR

voltages are maintained within 1% of 1/2V

DDR

. The
controller operates in synchronous rectification mode to
ensure balanced current sourcing and sinking capabili­ty of up to 25A. With a shutdown current of less than
5µA, the MAX1917 is the best choice for low-power
notebook applications, as well as servers and desktop
computers. An all N-FET design optimizes efficiency.
The MAX1917 can also be used for generating V

DDR

and as a general-purpose step-down controller with
variable switching frequency as high as 1MHz with few
additional components.

The MAX1917 uses Maxim’s proprietary Quick-PWM™
architecture for fast transient response up to 96% effi­ciency, and the smallest external components. Output
current monitoring is achieved without sense resistors
by monitoring the bottom FET’s drain-to-source voltage.
The current-limit threshold is programmable through an
external resistor. The MAX1917 comes in a space-sav­ing 16-pin QSOP package.

Applications

Features

♦ 25A Sourcing and Sinking Current

♦ Automatically Sets VTT to 1/2V

DDR

♦ VTT and VTTR Within 1% of 1/2V

DDR

♦ Smallest Output Capacitors

♦ 4.5V to 14V (or 28V with Resistor-Divider) Input

Voltage Range

♦ 1.5V to 3.6V Input DDR Range

♦ 200kHz/300kHz/400kHz/550kHz Preset Switching

Frequencies

♦ Variable Switching Frequency of Up to 1MHz

♦ Overcurrent Protection Without Current-Sense

Resistor

♦ Internal Soft-Start

♦ VTTR Reference Sources and Sinks Up to 25mA

♦ Quick-PWM Control for Fastest Loop Response

♦ Up to 96% Efficiency

♦ 16-Pin QSOP Package

MAX1917

Tracking, Sinking and Sourcing, Synchronous Buck

Controller for DDR Memory and Termination Supplies

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

MAX1917

V

IN

(2.5V TO 15V)

POK

VDDR

EN/HSD

POK

DDR

V+

REF

ILIM

FSEL

GND

DH

VL

BST

DL

LX

PGND

VTT

VTTR

V

OUT

VTTR

(4.5V TO 14V)

VL

Typical Operating Circuit

19-2335; Rev 1; 6/02

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Pin Configuration

Quick-PWM is a trademark of Maxim Integrated Products, Inc.

DDR Memory Power
Supply

Processor or DSP Core
Supply

AGTL Bus Termination
Supply

Notebook Computers
Desktop Computers
Storage
Networking Systems

PART TEMP RANGE PIN-PACKAGE

MAX1917EEE -40°C to +85°C 16 QSOP

TOP VIEW

1

EN/HSD LX

2

DDR

POK

3

4

VTT

ILIM

5

6

FSEL

7

REF

GND

8

16

15

DH

14

BST

MAX1917EEE

QSOP

13

PGND

12

DL

VL

11

10

V+

9

VTTR

MAX1917

Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V+ = 12V, V

EN/HSD

= V

DDR

= 2.5V, CVL= 4.7µF, C

VTTR

= 1µF, C

REF

= 0.22µF, V

FSEL

= 0, ILIM = VL, PGND = LX = POK = GND,

BST = VL. Specifications are for T

A

= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise specified.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

V+ to GND ..............................................................-0.3V to +15V

EN/HSD to GND .....................................................-0.3V to +16V

VL to GND ................................................................-0.3V to +6V

PGND to GND .......................................................-0.3V to +0.3V

VTT, DDR, POK to GND ...........................................-0.3V to +6V

REF, VTTR, DL, ILIM, FSEL to GND ................-0.3V to VL + 0.3V

LX to PGND ............................................................-0.3V to +30V

BST to GND ............................................................-0.3V to +36V

DH to LX ......................................................-0.3V to V

BST

+ 0.3V

LX to BST..................................................................-6V to +0.3V

REF Short Circuit to GND ...........................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

16-Pin QSOP (derate up to +70°C)..............................667mW

16-Pin QSOP (derating above +70°C).....................8.3mW/°C

Operating Temperature Range

Extended .........................................................-40°C to +85°C

Junction Temperature......................................................+150°C

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

Lead Temperature (soldering 10s.) .................................+300°C

V+ Input Voltage Range

EN/HSD Input Voltage Range Enabled 1.5 15.0 V

DDR Input Voltage Range 0 3.6 V

V+ Supply Current VTT = 2.0V 0.8 1.2 mA

DDR Supply Current 115 250 µA

EN/HSD Supply Current 510µA

VL Supply Current VL = V+ = 5.5V, VTT = 2.0V 0.8 1.2 mA

V+ Shutdown Supply Current EN/HSD = 0V 3 5 µA

DDR Shutdown Supply Current EN/HSD = 0V 1 µA

VL Shutdown Supply Current VL = V+ = 5.5V 3 5 µA

VL Undervoltage Lockout
Threshold

VTT

VTT Input Bias Current V

VTT Feedback Voltage Range 0 1.8 V

VTT Feedback Voltage
Accuracy

REFERENCE

Reference Output Voltage V+ = VL = 4.5V to 5.5V, I

Reference Load Regulation V+ = VL = 5V, I

Reference UVLO V+ = VL = 5V 1.5 1.6 1.7 V

VTTR

VTTR Output Voltage Range 0 1.8 V

VTTR Output Accuracy

PARAMETER CONDITIONS MIN TYP MAX UNITS

VL = V+ 4.5 5.5

Rising edge, hysteresis = 40mV 4.05 4.25 4.40 V

VTT

Overload range, V

Overload range, V

I

VTTR

I

VTTR

I

VTTR

= 2.5V -0.1 0 µA

= 1.8V 49.5 50 50.5

DDR

= 3.6V 49.5 50 50.5

DDR

REF

= 0 to 50µA 10 mV

REF

= -5mA to +5mA 49.5 50 50.5

= -25mA to +25mA, V

= -25mA to +25mA, V

= 0 1.98 2.00 2.02 V

= 1.8V 49 50 51

DDR

= 3.6V 49.5 50 50.5

DDR

5.5 14.0

%V

%V

V

DDR

DDR

MAX1917

Tracking, Sinking and Sourcing, Synchronous Buck

Controller for DDR Memory and Termination Supplies

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 12V, V

EN/HSD

= V

DDR

= 2.5V, CVL= 4.7µF, C

VTTR

= 1µF, C

REF

= 0.22µF, V

FSEL

= 0, ILIM = VL, PGND = LX = POK = GND,

BST = VL. Specifications are for T

A

= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise specified.)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Thermal Shutdown Rising temperature, typical hysteresis = 15°C +160 °C

SOFT-START

ILIM Ramp Period

OSCILLATOR

Ramps the ILIM trip threshold from 20% to 100%

in 20% increments

1.7 ms

FSEL = VL 200

Oscillator Frequency

FSEL = unconnected 300

FSEL = REF 400

FSEL = GND 550

kHz

FSEL = VL 2.18 2.5 2.83

On Time (Note 1)

FSEL not connected 1.45 1.67 1.89
FSEL = REF 1.09 1.25 1.41

FSEL = GND 0.82 0.91 1.00

µs

Minimum Off Time (Note 1) 350 400 ns

CURRENT LIMIT

Current-Limit Threshold
(Positive Direction)

Current-Limit Threshold
(Negative Direction)

ILIM Input Current 5µA

V

REGULATOR

L

Output Voltage

Line Regulation 5.5V < V+ < 14V, IVL = 10mA 0.2 %

RMS Output Current 35 mA
Bypass Capacitor ESR < 100mΩ 2.2 µF

DRIVER

DH Gate-Driver On-Resistance V

DL Gate-Driver On-Resistance
(Source)

DL Gate-Driver On-Resistance
(Sink)

Dead Time

FSEL LOGIC

Logic Input Current -3 3 µA

Logic GND Level 0.5 V

Logic REF Level FSEL = VREF 1.65 2.35 V

Logic Float Level FSEL floating 3.15 3.85 V

LX to PGND, ILIM = VL 90 100 110

LX to PGND, R

LX to PGND, R

LX to PGND, ILIM = VL, with percentage of positive
current-limit threshold

5.5V < V+ < 14V
1mA < I

BST

DL high state 1.6 3 Ω

DL low state 0.75 1.25 Ω

DL rising 32

DL falling 30

< 35mA

VL

- VLX = 5V 1.4 2.5 Ω

= 100kΩ 40 50 60

ILIM

= 400kΩ 170 200 230

ILIM

-90 -110 -130 %

4.8 5.0 5.2 V

mV

ns

MAX1917

Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 12V, V

EN/HSD

= V

DDR

= 2.5V, CVL= 4.7µF, C

VTTR

= 1µF, C

REF

= 0.22µF, V

FSEL

= 0, ILIM = VL, PGND = LX = POK = GND,

BST = VL. Specifications are for T

A

= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise specified.)

ELECTRICAL CHARACTERISTICS

(V+ = 12V, V

EN/HSD

= V

DDR

= 2.5V, CVL= 4.7µF, C

VTTR

= 1µF, C

REF

= 0.22µF, V

FSEL

= 0, ILIM = VL, PGND = LX = POK = GND,

BST = VL. Specifications are for T

A

= -40°C to +85°C, unless otherwise specified.) (Note 2)

Logic VL Level FSEL = VL VL - 0.4 V

EN/HSD LOGIC

EN/HSD Shutdown Current Max I

Logic High VL = V+ = 4.5V to 5.5V, 100mV hysteresis 1.45 V

Logic Low VL = V+ = 4.5V to 5.5V 0.8 V

POWER-OK OUTPUT

Upper VTT Threshold 110 112 114

Lower VTT Threshold 86 88 90

Upper VTTR Threshold 110 112 114

Lower VTTR Threshold 86 88 90

POK Output Low Level I

POK Output High Leakage V

PARAMETER CONDITIONS MIN TYP MAX UNITS

= 2mA 0.4 V

SINK

POK

for V

EN/HSD

= 5.5V 5 µA

= 0.8V 0.5 3.0 µA

EN/HSD

%V

%V

%V

%V

DDR

2

DDR

2

DDR

2

DDR

2

/

/

/

/

V+ Input Voltage Range

EN/HSD Input Voltage Range Enabled 1.5 15.0 V

DDR Input Voltage Range 0 3.6 V

V+ Supply Current VTT = 2.0V 1.2 mA

DDR Supply Current 250 µA

EN/HSD Supply Current V

VL Supply Current VL = V+ = 5.5V 1.2 mA

V+ Shutdown Supply Current EN/HSD = 0V 5 µA

DDR Shutdown Supply Current EN/HSD = 0V 1 µA

VL Shutdown Supply Current VL = V+ = 5.5V 5 µA

VL Undervoltage Lockout
Threshold

VTT

VTT Input Bias Current V

VTT Feedback Voltage Range 0 1.8 V

VTT Feedback Voltage
Accuracy

REFERENCE

Reference Output Voltage V+ = VL = 4.5V to 5.5V, I

Reference Load Regulation V+ = VL = 5V, I

PARAMETER CONDITIONS MIN TYP MAX UNITS

VL = V+ 4.5 5.5 V

EN/HSD

Rising edge, hysteresis = 40mV 4.05 4.40 V

VTT

Overload range, V

Overload range, V

= 2.5V 10 µA

= 2.5V -0.15 0 µA

= 1.8V 49.5 50.5

DDR

= 3.6V 49.5 50.5

DDR

REF

= 0 to 50µA 10 mV

REF

= 0 1.98 2.02 V

5.5 14.0 V

%V

DDR

MAX1917

Tracking, Sinking and Sourcing, Synchronous Buck

Controller for DDR Memory and Termination Supplies

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 12V, V

EN/HSD

= V

DDR

= 2.5V, CVL= 4.7µF, C

VTTR

= 1µF, C

REF

= 0.22µF, V

FSEL

= 0, ILIM = VL, PGND = LX = POK = GND,

BST = VL. Specifications are for T

A

= -40°C to +85°C, unless otherwise specified.) (Note 2)

Reference UVLO V+ = VL = 5V 1.5 1.7 V

VTTR

VTTR Output Voltage Range 0 1.8 V

OSCILLATOR

PARAMETER CONDITIONS MIN TYP MAX UNITS

On Time (Note 1)

I

VTTR

I

VTTR

I

VTTR

FSEL = VL 2.18 2.83

FSEL not connected 1.45 1.89

FSEL = REF 1.09 1.41

FSEL = GND 0.82 1.00

= -5mA to +5mA 49.5 50.5

= -25mA to +25mA, V

= -25mA to +25mA, V

DDR

DDR

= 1.8V 49 51VTTR Output Accuracy

= 3.6V 49.5 50.5

%V

DDR

µs

Minimum Off Time (Note 1) 400 ns

CURRENT LIMIT

Current-Limit Threshold
(Positive Direction)

Current-Limit Threshold
(Negative Direction)

LX to PGND, ILIM = VL 85 110

LX to PGND, R

LX to PGND, R

LX to PGND, ILIM = VL, with percentage of positive
current-limit threshold

= 100kΩ 35 60

ILIM

= 400kΩ 160 230

ILIM

-90 -130 %

mV

VL REGULATOR
Output Voltage 5.5V < V+

< 14V; 1mA < I

< 35mA 4.8 5.2 V

VL

RMS Output Current 35 mA
Bypass Capacitor ESR < 100mΩ 2.2 µF

FSEL LOGIC

Logic Input Current 3µA

Logic GND Level 0.5 V

Logic REF Level FSEL = VREF 1.65 2.35 V

Logic Float Level FSEL floating 3.15 3.85 V

Logic VL Level FSEL = VL VL - 0.4 V

EN/HSD LOGIC

EN/HSD Shutdown Current I

Logic High VL = V+ = 4.5V to 5.5V, 100mV hysteresis 1.45 V

Logic Low VL = V+ = 4.5V to 5.5V 0.8 V

POWER-OK OUTPUT

Upper VTT Threshold 110 114

Lower VTT Threshold 86 90

EN/HSD

for V

= 0.8V 0.5 3.0 µA

EN/HSD

%V

%V

DDR

/2

DDR

/2

Note 1: On Time and Off Time specifications are measured from 50% point to 50% point at the DH pin with LX forced to 0V, BST

forced to 5V, and a 250pF capacitor connected from DH to LX. Actual in-circuit times may differ due to MOSFET switching
speeds.

Note 2: Specifications to -40°C are guaranteed by design and are not production tested.

MAX1917

Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 12V, V

EN/HSD

= V

DDR

= 2.5V, CVL= 4.7µF, C

VTTR

= 1µF, C

REF

= 0.22µF, V

FSEL

= 0, ILIM = VL, PGND = LX = POK = GND,

BST = VL. Specifications are for T

A

= -40°C to +85°C, unless otherwise specified.) (Note 2)

Typical Operating Characteristics

(V+ = 12V, V

OUT

= 1.25V, TA= +25°C, unless otherwise noted.)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Upper VTTR Threshold 110 114

Lower VTTR Threshold 86 90

POK Output Low Level I

POK Output High Leakage V

EFFICIENCY vs. LOAD CURRENT

100

VIN = 2.5V

95

90

85

80

75

70

EFFICIENCY (%)

65

60

55

50

0.1 1.0 10.0

= 2mA 0.4 V

SINK

POK

= 5.5V 5 µA

AT 1.25V OUTPUT

96

94

MAX1917 toc01

92

VIN = 5V

VIN = 2V

CIRCUIT OF FIGURE 3

LOAD CURRENT (A)

90

88

86

84

EFFICIENCY (%)

82

80

78

76

0.1 1.0 10.0

EFFICIENCY vs. LOAD CURRENT

AT 0.9V OUTPUT

VIN = 2.5V

VIN = 5V

CIRCUIT OF FIGURE 3

LOAD CURRENT (A)

EFFICIENCY vs. LOAD CURRENT

AT 1.25V OUTPUT

100

VIN = 2.5V

90

MAX1917 toc02

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

0.1 1.0 10.0

VIN = 5V

VIN = 12V

CIRCUIT OF FIGURE 4

LOAD CURRENT (A)

%V

%V

DDR

/2

DDR

/2

MAX1917 toc03

EFFICIENCY vs. LOAD CURRENT

AT 0.9V OUTPUT

95

90

VIN = 2.5V

85

80

75

70

EFFICIENCY (%)

65

60

55

50

0.1 1.0 10.0

VIN = 5V

CIRCUIT OF FIGURE 4

LOAD CURRENT (A)

MAX1917 toc04

FREQUENCY vs. LOAD CURRENT

AT 1.25V OUTPUT

650

600

550

500

450

FREQUENCY (kHz)

400

350

300

-8 -4 -2-6 02468

VIN = 2.5V

VIN = 5V

VIN = 12V

CIRCUIT OF FIGURE 3

LOAD CURRENT (A)

MAX1917 toc05

FREQUENCY (kHz)

FREQUENCY vs. LOAD CURRENT

AT 0.9V OUTPUT

650

600

550

500

450

400

350

300

-8 -2 0-6-4 2468

VIN = 2.5V

LOAD CURRENT (A)

MAX1917 toc06

VIN = 5V

CIRCUIT OF FIGURE 3