Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +165°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
IN
= +15V, V
DD
= AV
DD
= V
SHDNA
= V
SHDNB
= V
BST
= V
ILIM
= 5V, V
OUT
= V
REFIN
= V
VTTI
= 2.5V, UVP/OVP = STBY = FB =
SKIP
= GND, PGND1 = PGND2 = LX = GND, TON = OPEN, V
VTTS
= V
VTT
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values
are at T
A
= +25°C.) (Note 1)
PARAMETER
MAIN PWM CONTROLLER
Input Voltage Range
Output Adjust Range
Output Voltage Accuracy
(Note 2)
Soft-Start Ramp Time
t
SS
V
IN
V
DD
, AV
DD
V
OUT
FB = OUT
FB = GND
FB = V
DD
Rising edge of
SHDNA
to full current limit
TON = GND (600kHz)
On-Time
t
ON
V
IN
= 15V,
V
OUT
= 1.5V
(Note 3)
(Note 3)
SHDNA
=
SHDNB
= GND
All on (PWM, VTT, and VTTR on)
AV
DD
Quiescent Supply Current
I
AVDD
SHDNA
= GND (only VTT and VTTR on)
STBY = AV
DD
(only VTTR and PWM on)
SHDNB
= GND (only PWM on)
AV
DD
+ V
DD
Shutdown Supply
Current
AV
DD
Undervoltage-Lockout
Threshold
V
DD
Quiescent Supply Current
I
VDD
SHDNA
=
SHDNB
= GND
Rising edge of V
IN
Hysteresis
Set V
FB
= 0.8V
4.1
TON = REF (450kHz)
TON = OPEN (300kHz)
TON = AV
DD
(200kHz)
Minimum Off-Time
V
IN
Quiescent Supply Current
V
IN
Shutdown Supply Current
t
OFF_MIN
I
IN
170
213
316
461
200
2
4.5
0.7
0.693
2.47
1.78
0.7
2.5
1.8
1.7
194
243
352
516
300
25
1
2.5
2
1
0.5
2
4.25
50
1
5
219
273
389
571
450
40
5
5
4
2
1
10
4.4
µA
V
mV
µA
mA
ns
µA
µA
ns
28
5.5
5.5
0.707
2.53
1.82
ms
V
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
Maxim Integrated
MAX8550/MAX8551
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +15V, V
DD
= AV
DD
= V
SHDNA
= V
SHDNB
= V
BST
= V
ILIM
= 5V, V
OUT
= V
REFIN
= V
VTTI
= 2.5V, UVP/OVP = STBY = FB =
SKIP
= GND, PGND1 = PGND2 = LX = GND, TON = OPEN, V
VTTS
= V
VTT
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values
are at T
A
= +25°C.) (Note 1)
PARAMETER
REFERENCE
Reference Voltage
Reference Load Regulation
REF Undervoltage Lockout
FAULT DETECTION
OVP Trip Threshold
(Referred to Nominal V
OUT
)
UVP Trip Threshold
(Referred to Nominal V
OUT
)
POK1 Trip Threshold
(Referred to Nominal V
OUT
)
POK2 Trip Threshold
(Referred to Nominal V
VTTS
and V
VTTR
)
UVP Blanking Time
OVP, UVP, POK_ Propagation
Delay
POK_ Output Low Voltage
POK_ Leakage Current
ILIM Adjustment Range
ILIM Input Leakage Current
Current-Limit Threshold (Fixed)
PGND1 to LX
Current-Limit Threshold
(Adjustable) PGND1 to LX
Current-Limit Threshold (Negative
Direction) PGND1 to LX
Current-Limit Threshold (Negative
Direction) PGND1 to LX
Zero-Crossing Detection
Threshold PGND1 to LX
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
V
ILIM
= 2V
SKIP
= AV
DD
(Note 4)
SKIP
= AV
DD
, V
ILIM
= 2V (Note 4)
45
170
-75
50
200
-60
-250
3
+160
15
V
ILIM
Lower level, falling edge, 1% hysteresis
Upper level, rising edge, 1% hysteresis
Lower level, falling edge, 1% hysteresis
Upper level, rising edge, 1% hysteresis
From rising edge of
SHDNA
OVP not applicable in MAX8551
I
SINK
= 4mA
V
POK_
= 5.5V, V
FB
= 0.8V, V
VTTS
= 1.3V
0.25
UVP/OVP = AVDD (Note 4)
112
65
87
107
87.5
107.5
10
116
70
90
110
90
110
20
10
0.3
1
2.00
0.1
55
235
-45
120
75
93
113
92.5
%
112.5
40
ms
µs
V
µA
V
µA
mV
mV
mV
mV
mV
°C
°C
%
%
%
V
REF
AV
DD
= 4.5V to 5.5V; I
REF
= 0
I
REF
= 0 to 50µA
V
REF
rising
Hysteresis
1.93
300
1.98
2
2.02
0.01
V
V
V
mV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Maxim Integrated
3
MAX8550/MAX8551
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +15V, V
DD
= AV
DD
= V
SHDNA
= V
SHDNB
= V
BST
= V
ILIM
= 5V, V
OUT
= V
REFIN
= V
VTTI
= 2.5V, UVP/OVP = STBY = FB =
SKIP
= GND, PGND1 = PGND2 = LX = GND, TON = OPEN, V
VTTS
= V
VTT
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values
are at T
A
= +25°C.) (Note 1)
PARAMETER
MOSFET DRIVERS
DH Gate-Driver On-Resistance
DL Gate-Driver On-Resistance in
High State
DL Gate-Driver On-Resistance in
Low State
Dead Time (Additional to
Adaptive Delay)
INPUTS AND OUTPUTS
Logic Input Threshold
(SHDN_, STBY,
SKIP
(Note 4))
Logic Input Current
(SHDN_, STBY,
SKIP
(Note 4))
Dual-Mode™ Input Logic
Levels (FB)
Input Bias Current (FB)
High
Four-Level Input Logic Levels
(TON, OVP/UVP (Note 4))
Floating
REF
Low
Logic Input Current
(TON, OVP/UVP (Note 4))
FB = GND
OUT Input Resistance
OUT Discharge-Mode
On-Resistance
DL Turn-On Level During
Discharge Mode
(Measured at OUT)
FB = AV
DD
FB adjustable mode
(Note 4)
-3
90
70
400
175
135
800
10
Low (2.5V output)
High (1.8V output)
2.1
-0.1
AV
DD
-
0.4
3.15
1.65
3.85
2.35
0.5
+3
350
270
1600
25
Ω
kΩ
µA
V
+0.1
Rising edge
Hysteresis
-1
1.20
1.7
225
+1
0.05
2.20
V
mV
µA
V
µA
DH falling to DL rising
DL falling to DH rising
V
BST
- V
LX
= 5V
1
1
0.5
30
30
4
4
3
Ω
Ω
Ω
ns
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
(Note 4)
0.3
V
Dual Mode is a trademark of Maxim Integrated Products, Inc.
4
Maxim Integrated
MAX8550/MAX8551
Integrated DDR Power-Supply Solutions for
Desktops, Notebooks, and Graphic Cards
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +15V, V
DD
= AV
DD
= V
SHDNA
= V
SHDNB
= V
BST
= V
ILIM
= 5V, V
OUT
= V
REFIN
= V
VTTI
= 2.5V, UVP/OVP = STBY = FB =
SKIP
= GND, PGND1 = PGND2 = LX = GND, TON = OPEN, V
VTTS
= V
VTT
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values
are at T
A
= +25°C.) (Note 1)
PARAMETER
VTTI Input Voltage Range
VTTI Supply Current
VTTI Shutdown Current
REFIN Input Impedance
REFIN Range
REFIN Lockout Threshold
Soft-Start Charge Current
VTT Internal MOSFET High-Side
On-Resistance
VTT Internal MOSFET Low-Side
On-Resistance
VTT Output Accuracy
(Referred to V
REFIN
/ 2)
VTT Load Regulation
VTT Current Limit
VTTS Input Current
VTTR Output Error
(Referred to V
REFIN
/ 2)
VTTR Current Limit
I
VTTS
I
SS
V
REFIN
V
REFIN
rising
Hysteresis
V
SS
= 0
I
VTT
= -100mA, V
VTTI
= 1.5V,
AV
DD
= 4.5V
I
VTT
= 100mA, AV
DD
= 4.5V
V
REFIN
= 1.5V or 2.5V, I
VTT
= 1mA
V
REFIN
= 2.5V, I
VTT
= 0 to
±1.5A
V
REFIN
= 1.5V, I
VTT
= 0 to
±1A
VTT = 0 or VTTI
V
VTTS
= 1.5V, VTT open
V
REFIN
= 1.5V or 2.5V, I
VTTR
= 0
V
VTTR
= 0 or V
VTTI
-1
±23
±40
±3
-1
1
1
±5
0.1
±6.5
1
+1
±60
SYMBOL
V
VTTI
I
VTTI
I
VTT
= I
VTTR
= 0
SHDNA
=
SHDNB
= GND
V
REFIN
= 2.5V
12
1
0.7
75
4
0.3
0.3
+1
20
CONDITIONS
MIN
1
<0.1
TYP
MAX
2.8
1
10
30
2.8
0.9
UNITS
V
mA
µA
kΩ
V
V
mV
µA
Ω
Ω
%
%
A
µA
%
mA
LINEAR REGULATORS (VTTR AND VTT)
Note 1:
Specifications to -40°C are guaranteed by design, not production tested.
Note 2:
When the inductor is in continuous conduction, the output voltage has a DC regulation level higher than the error-compara-
tor threshold by 50% of the ripple. In discontinuous conduction, the output voltage has a DC regulation level higher than the
trip level by approximately 1.5% due to slope compensation.
Note 3:
On-time and off-time specifications are measured from 50% point to 50% point at the DH pin with LX = GND, V
BST
= 5V,
and a 250pF capacitor connected from DH to LX. Actual in-circuit times may differ due to MOSFET switching speeds.
