19-2335; Rev 1; 6/02
Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies
General Description
The MAX1917 provides a complete power-manage-
ment solution for DDR memory. It contains a synchro-
nous 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 capabili-
ty 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% effi-
ciency, 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-sav-
ing 16-pin QSOP package.
o
25A Sourcing and Sinking Current
o
Automatically Sets VTT to 1/2V
DDR
o
VTT and VTTR Within 1% of 1/2V
DDR
o
Smallest Output Capacitors
o
4.5V to 14V (or 28V with Resistor-Divider) Input
Voltage Range
o
1.5V to 3.6V Input DDR Range
o
200kHz/300kHz/400kHz/550kHz Preset Switching
Frequencies
o
Variable Switching Frequency of Up to 1MHz
o
Overcurrent Protection Without Current-Sense
Resistor
o
Internal Soft-Start
o
VTTR Reference Sources and Sinks Up to 25mA
o
Quick-PWM Control for Fastest Loop Response
o
Up to 96% Efficiency
o
16-Pin QSOP Package
Features
MAX1917
Applications
DDR Memory Power
Supply
Processor or DSP Core
Supply
AGTL Bus Termination
Supply
Notebook Computers
Desktop Computers
Storage
Networking Systems
Ordering Information
PART
MAX1917EEE
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
16 QSOP
Typical Operating Circuit
V
IN
(2.5V TO 15V)
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Pin Configuration
POK
EN/HSD
POK
VDDR
DDR
(4.5V TO 14V)
V+
REF
ILIM
FSEL
GND
DH
VL
V
OUT
TOP VIEW
EN/HSD 1
DDR 2
POK 3
VTT 4
ILIM 5
FSEL 6
REF 7
GND 8
16 LX
15 DH
14 BST
MAX1917
BST
LX
DL
PGND
VTT
VTTR
VTTR
MAX1917EEE
13 PGND
12 DL
11 VL
10 V+
9
VTTR
VL
QSOP
________________________________________________________________
Maxim Integrated Products
1
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.
Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies
MAX1917
ABSOLUTE MAXIMUM RATINGS
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
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.
ELECTRICAL CHARACTERISTICS
(V+ = 12V, V
EN/HSD
= V
DDR
= 2.5V, C
VL
= 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 T
A
= +25°C, unless otherwise specified.)
PARAMETER
V+ Input Voltage Range
EN/HSD Input Voltage Range
DDR Input Voltage Range
V+ Supply Current
DDR Supply Current
EN/HSD Supply Current
VL Supply Current
V+ Shutdown Supply Current
DDR Shutdown Supply Current
VL Shutdown Supply Current
VL Undervoltage Lockout
Threshold
VTT
VTT Input Bias Current
VTT Feedback Voltage Range
VTT Feedback Voltage
Accuracy
REFERENCE
Reference Output Voltage
Reference Load Regulation
Reference UVLO
VTTR
VTTR Output Voltage Range
I
VTTR
= -5mA to +5mA
VTTR Output Accuracy
I
VTTR
= -25mA to +25mA, V
DDR
= 1.8V
I
VTTR
= -25mA to +25mA, V
DDR
= 3.6V
0
49.5
49
49.5
50
50
50
1.8
50.5
51
50.5
%V
DDR
V
V+ = VL = 4.5V to 5.5V, I
REF
= 0
V+ = VL = 5V, I
REF
= 0 to 50µA
V+ = VL = 5V
1.5
1.6
1.98
2.00
2.02
10
1.7
V
mV
V
Overload range, V
DDR
= 1.8V
Overload range, V
DDR
= 3.6V
V
VTT
= 2.5V
-0.1
0
49.5
49.5
50
50
0
1.8
50.5
50.5
µA
V
%V
DDR
VL = V+ = 5.5V, VTT = 2.0V
EN/HSD = 0V
EN/HSD = 0V
VL = V+ = 5.5V
Rising edge, hysteresis = 40mV
4.05
3
4.25
VTT = 2.0V
VL = V+
Enabled
CONDITIONS
MIN
5.5
4.5
1.5
0
0.8
115
5
0.8
3
TYP
MAX
14.0
5.5
15.0
3.6
1.2
250
10
1.2
5
1
5
4.40
UNITS
V
V
V
mA
µA
µA
mA
µA
µA
µA
V
2
_______________________________________________________________________________________
Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 12V, V
EN/HSD
= V
DDR
= 2.5V, C
VL
= 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 T
A
= +25°C, unless otherwise specified.)
PARAMETER
Thermal Shutdown
SOFT-START
ILIM Ramp Period
OSCILLATOR
FSEL = VL
Oscillator Frequency
FSEL = unconnected
FSEL = REF
FSEL = GND
FSEL = VL
On Time (Note 1)
FSEL not connected
FSEL = REF
FSEL = GND
Minimum Off Time (Note 1)
CURRENT LIMIT
LX to PGND, ILIM = VL
Current-Limit Threshold
(Positive Direction)
Current-Limit Threshold
(Negative Direction)
ILIM Input Current
V
L
REGULATOR
Output Voltage
Line Regulation
RMS Output Current
Bypass Capacitor
DRIVER
DH Gate-Driver On-Resistance
DL Gate-Driver On-Resistance
(Source)
DL Gate-Driver On-Resistance
(Sink)
Dead Time
FSEL LOGIC
Logic Input Current
Logic GND Level
Logic REF Level
Logic Float Level
FSEL = VREF
FSEL floating
1.65
3.15
-3
3
0.5
2.35
3.85
µA
V
V
V
V
BST
- V
LX
= 5V
DL high state
DL low state
DL rising
DL falling
1.4
1.6
0.75
32
30
2.5
3
1.25
Ω
Ω
Ω
ns
ESR < 100mΩ
2.2
5.5V < V+ < 14V
1mA < I
VL
< 35mA
5.5V < V+ < 14V, I
VL
= 10mA
4.8
5.0
0.2
35
5.2
V
%
mA
µF
LX to PGND, R
ILIM
= 100kΩ
LX to PGND, R
ILIM
= 400kΩ
LX to PGND, ILIM = VL, with percentage of positive
current-limit threshold
90
40
170
-90
100
50
200
-110
5
110
60
230
-130
%
µA
mV
2.18
1.45
1.09
0.82
200
300
400
550
2.5
1.67
1.25
0.91
350
2.83
1.89
1.41
1.00
400
ns
µs
kHz
Ramps the ILIM trip threshold from 20% to 100%
in 20% increments
1.7
ms
CONDITIONS
Rising temperature, typical hysteresis = 15°C
MIN
TYP
+160
MAX
UNITS
°C
MAX1917
_______________________________________________________________________________________
3
Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies
MAX1917
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 12V, V
EN/HSD
= V
DDR
= 2.5V, C
VL
= 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 T
A
= +25°C, unless otherwise specified.)
PARAMETER
Logic VL Level
EN/HSD LOGIC
EN/HSD Shutdown Current
Logic High
Logic Low
POWER-OK OUTPUT
Upper VTT Threshold
Lower VTT Threshold
Upper VTTR Threshold
Lower VTTR Threshold
POK Output Low Level
POK Output High Leakage
I
SINK
= 2mA
V
POK
= 5.5V
110
86
110
86
112
88
112
88
114
90
114
90
0.4
5
%V
DDR
/
2
%V
DDR
/
2
%V
DDR
/
2
%V
DDR
/
2
V
µA
Max I
EN/HSD
for V
EN/HSD
= 0.8V
VL = V+ = 4.5V to 5.5V, 100mV hysteresis
VL = V+ = 4.5V to 5.5V
0.5
1.45
0.8
3.0
µA
V
V
FSEL = VL
CONDITIONS
MIN
VL - 0.4
TYP
MAX
UNITS
V
ELECTRICAL CHARACTERISTICS
(V+ = 12V, V
EN/HSD
= V
DDR
= 2.5V, C
VL
= 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)
PARAMETER
V+ Input Voltage Range
EN/HSD Input Voltage Range
DDR Input Voltage Range
V+ Supply Current
DDR Supply Current
EN/HSD Supply Current
VL Supply Current
V+ Shutdown Supply Current
DDR Shutdown Supply Current
VL Shutdown Supply Current
VL Undervoltage Lockout
Threshold
VTT
VTT Input Bias Current
VTT Feedback Voltage Range
VTT Feedback Voltage
Accuracy
REFERENCE
Reference Output Voltage
Reference Load Regulation
V+ = VL = 4.5V to 5.5V, I
REF
= 0
V+ = VL = 5V, I
REF
= 0 to 50µA
1.98
2.02
10
V
mV
Overload range, V
DDR
= 1.8V
Overload range, V
DDR
= 3.6V
V
VTT
= 2.5V
-0.15
0
49.5
49.5
0
1.8
50.5
50.5
µA
V
%V
DDR
V
EN/HSD
= 2.5V
VL = V+ = 5.5V
EN/HSD = 0V
EN/HSD = 0V
VL = V+ = 5.5V
Rising edge, hysteresis = 40mV
4.05
VTT = 2.0V
VL = V+
Enabled
CONDITIONS
MIN
5.5
4.5
1.5
0
TYP
MAX
14.0
5.5
15.0
3.6
1.2
250
10
1.2
5
1
5
4.40
UNITS
V
V
V
V
mA
µA
µA
mA
µA
µA
µA
V
4
_______________________________________________________________________________________
Tracking, Sinking and Sourcing, Synchronous Buck
Controller for DDR Memory and Termination Supplies
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 12V, V
EN/HSD
= V
DDR
= 2.5V, C
VL
= 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)
PARAMETER
Reference UVLO
VTTR
VTTR Output Voltage Range
I
VTTR
= -5mA to +5mA
VTTR Output Accuracy
OSCILLATOR
FSEL = VL
On Time (Note 1)
FSEL not connected
FSEL = REF
FSEL = GND
Minimum Off Time (Note 1)
CURRENT LIMIT
LX to PGND, ILIM = VL
Current-Limit Threshold
(Positive Direction)
Current-Limit Threshold
(Negative Direction)
VL REGULATOR
Output Voltage
RMS Output Current
Bypass Capacitor
FSEL LOGIC
Logic Input Current
Logic GND Level
Logic REF Level
Logic Float Level
Logic VL Level
EN/HSD LOGIC
EN/HSD Shutdown Current
Logic High
Logic Low
POWER-OK OUTPUT
Upper VTT Threshold
Lower VTT Threshold
110
86
114
90
%V
DDR
/2
%V
DDR
/2
I
EN/HSD
for V
EN/HSD
= 0.8V
VL = V+ = 4.5V to 5.5V, 100mV hysteresis
VL = V+ = 4.5V to 5.5V
0.5
1.45
0.8
3.0
µA
V
V
FSEL = VREF
FSEL floating
FSEL = VL
1.65
3.15
VL - 0.4
3
0.5
2.35
3.85
µA
V
V
V
V
ESR < 100mΩ
2.2
5.5V < V+ < 14V; 1mA < I
VL
< 35mA
4.8
5.2
35
V
mA
µF
LX to PGND, R
ILIM
= 100kΩ
LX to PGND, R
ILIM
= 400kΩ
LX to PGND, ILIM = VL, with percentage of positive
current-limit threshold
85
35
160
-90
110
60
230
-130
%
mV
2.18
1.45
1.09
0.82
2.83
1.89
1.41
1.00
400
ns
µs
I
VTTR
= -25mA to +25mA, V
DDR
= 1.8V
I
VTTR
= -25mA to +25mA, V
DDR
= 3.6V
0
49.5
49
49.5
1.8
50.5
51
50.5
%V
DDR
V
V+ = VL = 5V
CONDITIONS
MIN
1.5
TYP
MAX
1.7
UNITS
V
MAX1917
_______________________________________________________________________________________
5
Microchip MCU
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