19-0670; Rev 0; 11/06
KIT
ATION
EVALU
BLE
AVAILA
Dual and Combinable Graphics Core
Controller for Notebook Computers
General Description
Features
o
Dual-Output, Fixed-Frequency, Current-Mode
Control
o
Combinable Output for Higher Currents
o
Dynamic Output Voltages with Automatic Fault
Blanking and Transition Control
o
True Out-of-Phase Operation
o
True Differential Current Sense for Accurate
Current Limit and Current Balance
o
4V to 26V Input Range
o
100kHz to 600kHz Switching Frequency
o
0.5V to 2.5V Adjustable Outputs
o
Internal Integrator for High Output Accuracy
o
Stable with Low-ESR Output Capacitors
o
Independent Selectable PWM and Skip-Mode
Operation
o
Independent Power-Good Outputs
o
Soft-Start and Soft-Stop
o
2.5V Precision Reference
o
< 1µA Typical Shutdown Current
MAX8775
The MAX8775 is a dual, step-down, interleaved, fixed-
frequency, switch-mode power-supply (SMPS) con-
troller with synchronous rectification. It is intended for
GPU cores and I/O power generation in battery-pow-
ered systems. Flexible configuration allows the
MAX8775 to operate as two independent single-phase
regulators, or as one high-current two-phase regulator.
Configured in separate mode, the MAX8775 provides
power to two dynamic voltage rails, one for the GPU
core and the other for the I/O power rail. Configured in
combined mode, the MAX8775 functions as a two-
phase, high-current, single-output GPU core regulator,
powering the high-performance GPU engines used in
gaming machines and media center notebooks.
The REFIN voltage setting allows for multiple dynamic
output voltages required by the different GPU operating
and sleep states. Automatic fault blanking, forced-PWM
operation, and transition control are achieved by
detecting the voltage change at REFIN. Fixed-frequen-
cy operation with 180° out-of-phase interleaving mini-
mizes input ripple current from the lowest input
voltages up to the 26V maximum input. Current-mode
control allows the use of low-ESR output capacitors.
Internal integrators maintain high output accuracy over
the full line-and-load range, in both forced-PWM mode
and pulse-skipping mode. True differential current
sensing provides accurate output current limit and cur-
rent balance when operated in combined mode.
Independent on/off and skip control allows flexible
power sequencing and power management. Voltage-
controlled soft-start reduces inrush current. Soft-stop
gradually ramps the output voltage down, preventing
negative voltage dips.
Ordering Information
PART
MAX8775ETJ+
TEMP RANGE
-40°C to +85°C
PIN-
PACKAGE
32 Thin QFN
5mm x 5mm
PKG
CODE
T3255-5
+Denotes
lead-free package.
Pin Configuration
BST1
DL1
BST2
17
16
15
14
13
DH2
ON2
CSL2
CSH2
SKIP2
PGOOD2
CCI2
SLEW2
12
11
10
9
1
OVP1
2
OSC
3
REFIN1
4
V
CC
5
AGND
6
REF
7
REFIN2
8
OVP2
V
DD
DL2
19
LX1
LX2
18
Applications
2 to 4 Li+ Cells Battery-Powered Devices
Media Center and Gaming Notebooks
GPU and I/O Power Supplies
Tracking Output Power Supplies
TOP VIEW
24
DH1 25
ON1 26
CSL1 27
CSH1 28
SKIP1 29
PGOOD1 30
DTRANS 31
SLEW1 32
23
22
21
20
MAX8775
THIN QFN
5mm x 5mm
________________________________________________________________
Maxim Integrated Products
PGND
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.
Dual and Combinable Graphics Core
Controller for Notebook Computers
MAX8775
ABSOLUTE MAXIMUM RATINGS
VDD, VCC, CSH_, CSL_ to AGND............................-0.3V to +6V
ON_,
SKIP_,
PGOOD_ to AGND ..............................-0.3V to +6V
OVP_, REFIN_ to AGND ...........................................-0.3V to +6V
DTRANS
to AGND ....................................................-0.3V to +6V
REF, OSC, SLEW_, CCI2 to AGND ...........-0.3V to (V
CC
+ 0.3V)
BST1, BST2 to AGND .............................................-0.3V to +36V
LX1 to BST1..............................................................-6V to +0.3V
LX2 to BST2..............................................................-6V to +0.3V
DH1 to LX1 ..............................................-0.3V to (V
BST1
+ 0.3V)
DH2 to LX2 ..............................................-0.3V to (V
BST2
+ 0.3V)
DL1, DL2 to PGND .....................................-0.3V to (V
DD
+ 0.3V)
AGND to PGND .....................................................-0.3V to +0.3V
REF Short Circuit to AGND.........................................Continuous
REF Current ......................................................................+10mA
Continuous Power Dissipation (T
A
= +70°C)
32-Pin, 5mm x 5mm, Thin QFN
(derate 21.3mW/°C above +70°C) .............................1702mW
Operating Temperature Range ...........................-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
(Circuit of Figure 1, V
IN
= 12V,
SKIP_
= PGND = AGND, ON_ = V
CC
= 5V, separate mode,
T
A
= 0°C to +85°C,
unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
INPUT SUPPLIES
Input Voltage Range
V
CC
Undervoltage Lockout Threshold
Quiescent Supply Current (V
CC
)
Quiescent Supply Current (V
DD
)
Shutdown Supply Current (V
CC
)
Shutdown Supply Current (V
DD
)
SMPS CONTROLLERS
Output Voltage Accuracy
Output Voltage-Adjust Range
REFIN Operating Voltage-Adjust Range
REFINOK Threshold
REFIN Transient Detection Threshold
Combined-Mode Enabled Threshold
DC Load Regulation
Line Regulation Error
Switching-Frequency Accuracy
(Note 3)
Maximum Duty Factor
Minimum On-Time
f
OSC
D
MAX
t
ONMIN
(Note 4)
V
REFIN2
Either SMPS,
SKIP_
= V
CC
, zero to full load
Either SMPS, 4V < V
IN
< 26V
R
OSC
= 143kΩ (f
OSC
= 300kHz nominal)
R
OSC
= 71.5kΩ (f
OSC
= 600kHz nominal) to
432kΩ (f
OSC
= 99kHz nominal)
-10
-15
91
93
150
With respect to REFIN_,
V
REFIN_
-
REFIN_ = 0.5V to 2.5V,
V
CSL_
SKIP_
= V
CC
or GND (Note 1)
V
CSL_
V
REFIN_
Either SMPS (Note 2)
Either SMPS (Note 2)
Either SMPS
5mV (typ) hysteresis
3
-5
0.5
0.5
0.1
±25
V
CC
-
1
-0.1
0.03
+10
+15
%
%
ns
V
CC
-
0.4
0
+5
2.5
2.5
mV
V
V
V
mV
V
%
%/V
V
IN
V
BIAS
V
UVLO
I
CC
I
DD
V
CC
, V
DD
Rising edge, 50mV typical hysteresis
CSL_ forced above their regulation points
CSL_ forced above their regulation points,
SKIP mode
4
4.5
4.1
4.25
1.5
<1
<1
<1
26
5.5
4.5
2.5
5
5
5
V
V
mA
µA
µA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
I
CC(SHDN)
ON1 = ON2 = GND
I
DD(SHDN)
ON1 = ON2 = GND
2
_______________________________________________________________________________________
Dual and Combinable Graphics Core
Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
IN
= 12V,
SKIP_
= PGND = AGND, ON_ = V
CC
= 5V, separate mode,
T
A
= 0°C to +85°C,
unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
SMPS1 to SMPS2 Phase Shift
Slew-Rate Current
CURRENT LIMIT
Current-Limit Threshold
Current-Limit Threshold
(Negative)
Current-Limit Threshold
(Zero Crossing)
Idle Mode™ Threshold
REFERENCE (REF)
Reference Voltage
Reference Source Load Regulation
Reference Sink Load Regulation
REF Lockout Voltage
CURRENT BALANCE
Current-Balance Amplifier (GMI)
Offset
Current-Balance Amplifier (GMI)
Transconductance
FAULT DETECTION
OVP_ Adjust Range
Output Overvoltage Trip Threshold
Output Overvoltage Fault
Propagation Delay
Output Undervoltage Protection
Trip Threshold
Output Undevoltage Fault
Propagation Delay
Output Undervoltage Protection
Blanking Time
PGOOD_ Lower Trip Threshold
PGOOD_ Propagation Delay
t
PGOOD
_
t
UVP
t
BLANK
t
OVP
V
OVP_
Rising edge measured at CSL_,
with respect to OVP_ set voltage
50mV overdrive
Falling edge measured at CSL_,
with respect to error comparator threshold
50mV overdrive
From rising edge of ON_
Falling edge measured at CSL_,
with respect to error comparator threshold,
hysteresis = 1%
Falling edge, 50mV overdrive
-325
0.5
180
200
10
300
10
6144
-275
2.5
220
V
mV
µs
mV
µs
1/f
SW
[V(CSH1,CSL1) - V(CSH2,CSL2)] at I
CCI
= 0
ΔI
CCI
/Δ[V(CSH1,CSL1) - V(CSH2,CSL2)],
V
CCI
= V
OUT
= 0.5V to 2.5V, and
V(CSH_,CSL_) = -60.0mV to +60.0mV
-2
+2
mV
V
REF
ΔV
REF
V
CC
= 4.5V to 5.5V,
I
REF
= 0
I
REF
= 0µA to 250µA
I
REF
= -50µA
V
REF(UVLO)
Rising edge, hysteresis = 100mV
2.3
T
A
= +25°C to +85°C
T
A
= 0°C to +85°C
2.482
2.475
2.50
2.50
0.25
2.518
2.525
1.5
6
V
mV
mV
V
V
LIMIT
V
NEG
V
ZX
I
MIN
V
CSH
_ - V
CSL
_
V
CSH
_ - V
CSL
_,
SKIP_
= V
CC
V
CSH
_ - V
CSL
_,
SKIP_
= GND
V
CSH
_ - V
CSL
_,
SKIP_
= GND
3.6
26
-43
30
-36
3
6
8.4
34
-29
mV
mV
mV
mV
I
SLEW_
I
SLEWSS_
SYMBOL
CONDITIONS
SMPS2 starts after SMPS1
During transition
Startup and shutdown
4.0
0.70
MIN
TYP
50
180
4.75
0.95
5.5
1.20
MAX
UNITS
%
Deg
µA
MAX8775
200
µS
-180
-150
10
-120
mV
µs
Idle Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
3
Dual and Combinable Graphics Core
Controller for Notebook Computers
MAX8775
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
IN
= 12V,
SKIP_
= PGND = AGND, ON_ = V
CC
= 5V, separate mode,
T
A
= 0°C to +85°C,
unless otherwise
noted. Typical values are at T
A
= +25°C.)
PARAMETER
PGOOD_ Output Low Voltage
PGOOD_ Leakage Current
PGOOD_ Transition Blanking
Time
I
PGOOD
_
SYMBOL
I
SINK
= 4mA
High state, PGOOD_ forced to 5.5V
Measured from the time CSL_ reaches the
target voltage based on the slew rate set by
C
SLEW_
V(CCI2, REF),
0.5V
≤
V
FB
≤
2.5V
T
SHDN
R
DH
R
DL
I
DH
I
DL
(SOURCE)
CONDITIONS
MIN
TYP
MAX
0.4
1
UNITS
V
µA
µs
20
Current-Balance Fault
Comparator Thresholds
Thermal-Shutdown Threshold
GATE DRIVERS
DH_ Gate Driver On-Resistance
DL_ Gate Driver On-Resistance
(Note 5)
DH_ Gate Driver Source/
Sink Current
DL_ Gate Driver Source Current
DL_ Gate Driver Sink Current
Dead Time
Internal Boost Diode Switch R
ON
LX_, BST_ Leakage Current
INPUTS AND OUTPUTS
Logic Input Current
Logic Input-High Threshold
Input Leakage Current
Lower threshold,
0.84V
REF
Upper threshold,
1.2V
REF
2.0
2.9
+160
1.5
1.7
0.6
2
1.7
3.3
15
10
35
26
6.5
<2
-1
1.2
-0.15
1.7
2.2
V
3.0
°C
5
5
3
Ω
Ω
A
A
A
ns
9
20
+1
2.2
+0.15
Ω
µA
µA
V
µA
Hysteresis = 15°C
BST_ - LX_ forced to 5V (Note 5)
DL_, high state
DL_, low state
DH_ forced to 2.5V, BST_ - LX_ forced to 5V
DL_ forced to 2.5V
DL_ forced to 2.5V
DL_ to DH_
DH_ to DL_
Measure with 10mA of current
V
BST
_ = V
LX
_ = 28V
ON1, ON2,
DTRANS, SKIP1, SKIP2
ON1, ON2,
DTRANS, SKIP1, SKIP2,
hysteresis = 225mV
CSH_, CSL_, 0V, or V
DD
I
DL (SINK)
t
DEAD
4
_______________________________________________________________________________________
Dual and Combinable Graphics Core
Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
IN
= 12V,
SKIP_
= 0, ON_ = V
CC
= 5V, separate mode,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 6)
PARAMETER
INPUT SUPPLIES
Input Voltage Range
V
CC
Undervoltage Lockout
Quiescent Supply Current (V
CC
)
Quiescent Supply Current (V
DD
)
Shutdown Supply Current (V
CC
)
Shutdown Supply Current (V
DD
)
MAIN SMPS CONTROLLERS
PWM_ Output Voltage
Output Voltage Adjust Range
REFIN Operating Voltage Adjust
Range
Combined Mode Enabled
Switching Frequency Accuracy
(Note 2)
Maximum Duty Factor
Slew-Rate Current
CURRENT LIMIT
Current-Limit Threshold
REFERENCE (REF)
Reference Voltage
Reference Source Load Regulation
Reference Sink Load Regulation
CURRENT BALANCE
Current-Balance Amplifier (GMI)
Offset
[V(CSH1,CSL1) - V(CSH2,CSL2)] at I
CCI
= 0
-3
+3
mV
V
REF
ΔV
REF
V
CC
= 4.5V to 5.5V, I
REF
= 0
I
REF
= 0µA to 250µA
I
REF
= -50µA
2.462
2.538
2
10
V
mV
mV
V
LIMIT
V
CSH
_ - V
CSL
_
25
35
mV
With respect to REFIN_,
V
REFIN_
-
REFIN_ = 0.5V to 2.5V,
V
CSL_
SKIP_
= V
CC
or GND (Note 1)
V
CSL_
V
REFIN_
V
REFIN2
R
OSC
= 143kΩ (f
OSC
= 300kHz nominal)
f
OSC
D
MAX
I
SLEW_
During transition
I
SLEWSS_
Startup and shutdown
R
OSC
= 71.5kΩ (f
OSC
= 600kHz nominal) to
432kΩ (f
OSC
= 99kHz nominal)
Either SMPS (Note 2)
Either SMPS (Note 2)
-7.5
0.5
0.5
3
-15
-20
90
3.75
0.7
5.50
1.2
+15
+20
%
%
µA
+7.5
2.5
2.5
mV
V
V
V
V
IN
V
BIAS
V
UVLO
I
CC
I
DD
V
CC
, V
DD
Rising edge, 200mV typical hysteresis
CSL_ forced above their regulation points
CSL_ forced above their regulation points
ON1 = ON2 = GND
ON1 = ON2 = GND
4
4.5
4.1
26
5.5
4.5
2.5
5
5
5
V
V
mA
µA
µA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX8775
_______________________________________________________________________________________
5
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