19-1541; Rev 2; 8/05
IT
TION K
VALUA
E
BLE
AVAILA
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
General Description
Features
♦
Ultra-High Efficiency
♦
No Current-Sense Resistor (lossless I
LIMIT
)
♦
Quick-PWM with 100ns Load-Step Response
♦
1% V
OUT
Accuracy over Line and Load
♦
Dual-Mode Fixed 1.8V/3.3V/Adj or 2.5V/Adj Outputs
♦
Adjustable 1V to 5.5V Output Range
♦
2V to 28V Battery Input Range
♦
200/300/420/540kHz Nominal Switching Frequency
♦
Over/Undervoltage Protection
♦
1.7ms Digital Soft-Start
♦
Drives Large Synchronous-Rectifier FETs
♦
Power-Good Indicator
MAX1715
The MAX1715 PWM controller provides the high effi-
ciency, excellent transient response, and high DC out-
put accuracy needed for stepping down high-voltage
batteries to generate low-voltage CPU core, I/O, and
chipset RAM supplies in notebook computers.
Maxim’s proprietary Quick-PWM™ quick-response,
constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides
100ns “instant-on” response to load transients while
maintaining a relatively constant switching frequency.
The MAX1715 achieves high efficiency at a reduced
cost by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous-
rectifier MOSFETs.
Single-stage buck conversion allows this device to
directly step down high-voltage batteries for the highest
possible efficiency. Alternatively, two-stage conversion
(stepping down the +5V system supply instead of the
battery) at a higher switching frequency allows the mini-
mum possible physical size.
The MAX1715 is intended for CPU core, chipset,
DRAM, or other low-voltage supplies as low as 1V. The
MAX1715 is available in a 28-pin QSOP package. For
applications requiring VID compliance or DAC control
of output voltage, refer to the MAX1710/MAX1711 data
sheet. For a single-output version, refer to the MAX1714
data sheet.
Ordering Information
PART
MAX1715EEI
MAX1715EEI+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 QSOP
28 QSOP
+
Denotes lead-free package.
Applications
Notebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 1V
1.8V and 2.5V I/O Supply
5V INPUT
Minimal Operating Circuit
BATTERY
4.5V TO 28V
V
DD
V
CC
ILIM1
ILIM2
ON1
ON2
BST1
OUTPUT1
1.8V
DH1
LX1
DL1
TON
BST2
DH2
LX2
DL2
PGND
OUTPUT2
2.5V
V+
MAX1715
Pin Configuration appears at end of data sheet.
OUT1
OUT2
PGOOD
SKIP
REF
FB1 AGND FB2
Quick-PWM is a trademark of Maxim Integrated Products.
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
MAX1715
ABSOLUTE MAXIMUM RATINGS
V+ to AGND..............................................................-0.3 to +30V
V
DD
, V
CC
to AGND ..................................................-0.3V to +6V
PGND to AGND or V
CC
to V
DD
...........................................±0.3V
PGOOD, OUT_ to AGND..........................................-0.3V to +6V
ILIM_, FB_, REF,
SKIP,
TON,
ON_ to AGND ...........................................-0.3V to (V
DD
+ 0.3V)
DL_ to PGND ..............................................-0.3V to (V
DD
+ 0.3V)
BST_ to AGND........................................................-0.3V to +36V
DH1 to LX1 ...............................................-0.3V to (BST1 + 0.3V)
DH2 to LX2 ...............................................-0.3V to (BST2 + 0.3V)
LX1 to BST1..............................................................-6V to +0.3V
LX2 to BST2..............................................................-6V to +0.3V
REF Short Circuit to AGND.........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
28-Pin QSOP (derate 8.0mW/°C above +70°C).....640mW/°C
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, 4A components from Table 1, V
CC =
V
DD
= +5V,
SKIP
= AGND, V+ = 15V,
T
A
= 0°C to +85°C,
unless otherwise
noted.) (Note 1)
PARAMETER
Input Voltage Range
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
Load Regulation Error
Line Regulation Error
Output Voltage Range
OUT_ Input Resistance
FB_ Input Bias Current
Soft-Start Ramp Time
Battery voltage, V+
V
DD,
V
CC
V+ = 2V to 28V,
SKIP
= V
CC
, T
A
= +25°C
I
LOAD
= 0 to 4A
V+ = 2V to 28V,
SKIP
= V
CC
, T
A
= 0°C to +85°C
I
LOAD
= 0 to 4A
V+ = 2V to 28V,
SKIP
= V
CC
, T
A
= +25°C
I
LOAD
= 0 to 4A
V+ = 2V to 28V,
SKIP
= V
CC
, T
A
= 0°C to +85°C
I
LOAD
= 0 to 4A
I
LOAD
= 0 to 4A, each output
V
CC
= 4.5V to 5.5V, V+ = 4.5V to 28V
Adjustable mode, each output
FB_ = AGND
V
OUT
_ = AGND
Rising edge of ON_ to full current limit
TON = GND
On-Time (PWM1)
V+ = 24V, OUT1 = 2V
TON = REF
TON = open
TON = V
DD
TON = GND
On-Time (PWM2)
V+ = 24V, OUT2 = 2V
TON = REF
TON = open
TON = V
DD
2
112
142
210
300
154
198
292
420
1
75k
-0.1
1.7
136
173
247
353
182
234
336
484
160
205
280
407
215
270
380
550
ns
ns
0.1
FB1 = OUT1
FB1 = AGND
FB1 = V
CC
FB1 = OUT1
FB1 = AGND
FB1 = V
CC
FB2 = OUT2
FB2 = GND
FB2 = OUT2
FB2 = GND
CONDITIONS
MIN
2
4.5
0.99
1.782
3.267
0.985
1.773
3.250
0.99
2.475
0.985
2.463
1.00
1.8
3.3
1.00
1.8
3.3
1.00
2.5
1.00
2.5
0.4
0.2
5.5
TYP
MAX
28
5.5
1.01
1.818
3.333
1.105
1.827
3.350
1.01
V
2.525
1.105
V
2.538
%
%
V
Ω
µA
ms
V
V
UNITS
V
_______________________________________________________________________________________
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, 4A components from Table 1, V
CC =
V
DD
= +5V,
SKIP
= AGND, V+ = 15V,
T
A
= 0°C to +85°C,
unless otherwise
noted.) (Note 1)
PARAMETER
Minimum Off-Time
Quiescent Battery Current (V+)
Quiescent Supply Current
(V
CC
+ V
DD
)
Shutdown Supply Current
(V
CC
+ V
DD
)
Shutdown Supply Current (V+)
Reference Voltage
Reference Load Regulation
REF Sink Current
REF Fault Lockout Voltage
Overvoltage Trip Threshold
Overvoltage Fault Propagation
Delay
Output Undervoltage Threshold
Output Undervoltage Lockout
Time
Current-Limit Threshold
(Positive Direction, Fixed)
Current-Limit Threshold
(Positive Direction, Adjusted)
Current-Limit Threshold
(Negative Direction)
Current-Limit Threshold, Zero
Crossing
Thermal Shutdown Threshold
V
CC
Undervoltage Lockout
Threshold
DH Gate Driver On-Resistance
DL Gate Driver On-Resistance
(pull-up)
DL Gate Driver On-Resistance
(pull-down)
DH Gate Driver Source/Sink
Current
DL Gate Driver Source Current
DL Gate Driver Sink Current
Dead Time
Logic Input High Voltage
Logic Input Low Voltage
FB1 and FB2 forced above the regulation point
ON1 = ON2 = 0
ON1 = ON2 = 0
No external REF load
I
REF
= 0 to 50µA
REF in regulation
Falling edge, hysteresis = 40mV
With respect to error comparator threshold
FB_ forced 2% above trip threshold
With respect to error comparator threshold
From ON_ signal going high
PGND - LX_, I
LIM
= V
CC
PGND - LX_, I
LIM
resistor = 100kΩ
PGND - LX_, I
LIM
resistor = 400kΩ
PGND - LX_, T
A
= +25°C, I
LIM
= V
CC
PGND - LX_,
SKIP
= AGND
Hysteresis = 10°C
Rising edge, hysteresis = 20mV, PWM disabled below
this level
BST - LX forced to 5V
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 rising
DH rising
ON_,
SKIP
ON_,
SKIP
2.4
0.8
4.1
1.5
1.5
0.6
1
1
3
35
26
60
10
75
40
160
-145
-5
8.5
10
1.6
10.5
1.5
70
20
100
50
200
-120
3
150
4.4
5
5
2.5
80
30
125
60
240
-95
10
13
1.98
(Note 3)
CONDITIONS
MIN
TYP
400
25
1100
<1
<1
2
2
MAX
500
70
1600
5
5
2.02
0.01
UNITS
ns
µA
µA
µA
µA
V
V
µA
V
%
µs
%
ms
mV
mV
mV
mV
°C
V
Ω
Ω
Ω
A
A
A
ns
V
V
3
MAX1715
_______________________________________________________________________________________
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
MAX1715
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, 4A components from Table 1, V
CC =
V
DD
= +5V,
SKIP
= AGND, V+ = 15V,
T
A
= 0°C to +85°C,
unless otherwise
noted.) (Note 1)
PARAMETER
Logic Input Current
V
CC
level
TON Threshold
Float level
REF level
AGND level
Logic Input Current
Logic Input Current
PGOOD Trip Threshold
PGOOD Propagation Delay
PGOOD Output Low Voltage
PGOOD Leakage Current
TON (0 or V
CC
)
ON_,
SKIP
(0 or V
CC
)
Measured at FB_, with respect to error comparator
threshold, no load
Falling edge, FB_ forced 2% below PGOOD trip threshold
I
SINK
= 1mA
High state, forced to 5.5V
-3
-1
-8
-5.5
1.5
0.1
0.4
1
CONDITIONS
SKIP,
to deactivate OVP circuitry
MIN
-5
V
CC
- 0.4
3.15
1.65
3.85
2.35
0.5
3
1
-4
µA
µA
%
µs
V
µA
V
TYP
MAX
-1
UNITS
mA
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, 4A components from Table 1, V
CC =
V
DD
= +5V,
SKIP
= AGND, V+ = 15V,
T
A
= -40°C to +85°C,
unless otherwise
noted.) (Note 1)
PARAMETER
Input Voltage Range
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
Battery voltage, V+
V
DD,
V
CC
FB1 = OUT1
V+ = 2V to 28V,
SKIP
= V
CC
V+ = 4.5V to 28V,
SKIP
= V
CC
FB1 = AGND
FB1 = V
CC
FB2 = OUT2
FB2 = GND
TON = GND
On-Time (PWM1)
V+ = 24V, OUT1 = 2V
TON = REF
TON = open
TON = V
DD
TON = GND
On-Time (PWM2)
V+ = 24V, OUT2 = 2V
TON = REF
TON = open
TON = V
DD
Minimum Off-Time
(Note 3)
CONDITIONS
MIN
2
4.5
0.98
1.764
3.234
0.98
2.45
112
142
210
300
154
198
292
420
1.00
1.8
3.3
1.00
2.5
136
173
247
353
182
234
336
484
400
TYP
MAX
28
5.5
1.02
1.836
3.372
1.02
V
2.55
160
205
280
407
215
270
380
550
500
ns
ns
ns
V
UNITS
V
4
_______________________________________________________________________________________
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, 4A components from Table 1, V
CC =
V
DD
= +5V,
SKIP
= AGND, V+ = 15V,
T
A
= -40°C to +85°C,
unless otherwise
noted.) (Note 1)
PARAMETER
Quiescent Battery Current (V+)
Quiescent Supply Current
(V
CC
+ V
DD
)
Reference Voltage
Reference Load Regulation
Overvoltage Trip Threshold
Output Undervoltage Threshold
FB1 and FB2 forced above the regulation point
No external REF load
I
REF
= 0 to 50µA
With respect to error comparator threshold
With respect to error comparator threshold
10
60
75
32
160
12.5
70
100
50
200
150
4.1
2.4
0.8
-5
-1
4.4
1.97
CONDITIONS
MIN
TYP
25
1100
2
MAX
70
1600
2.03
0.01
15
80
125
62
mV
240
°C
V
V
V
mA
UNITS
µA
µA
V
V
%
%
mV
MAX1715
Current-Limit Threshold (positive
PGND - LX_, I
LIM
= V
CC
direction, fixed)
Current-Limit Threshold (positive PGND - LX_, I
LIM
resistor = 100kΩ
direction, adjusted)
PGND - LX_, I
LIM
resistor = 400kΩ
Thermal Shutdown Threshold
V
CC
Undervoltage Lockout
Threshold
Logic Input High Voltage
Logic Input Low Voltage
Logic Input Current
Hysteresis = 10°C
Rising edge, hysteresis = 20mV, PWM disabled below
this level
ON_,
SKIP
ON_,
SKIP
SKIP,
to deactivate OVP circuitry
Note 1:
Specifications to -40°C are guaranteed by design, and not production tested.
Note 2:
When the inductor is in continuous conduction, the output voltage will have a DC regulation higher than the trip level by
50% of the ripple. In discontinuous conduction (SKIP = AGND, light load) the output voltage will have DC regulation
higher than the trip level by approximately 1.5% due to slope compensation.
Note 3:
On-time and off-time specifications are measured from the 50% point at the DH pin with LX = PGND, V
BST
= 5V. Actual
in-circuit times may differ due to MOSFET switching speeds.
__________________________________________Typical Operating Characteristics
(Circuit of Figure 1, components from Table 1, V
IN
= +15V,
SKIP
= AGND, TON = unconnected, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(1.8V, 4A COMPONENTS, SKIP = GND)
MAX1715-01
EFFICIENCY vs. LOAD CURRENT
(1.8V, 4A COMPONENTS, SKIP = V
CC
)
MAX1715-02
EFFICIENCY vs. LOAD CURRENT
(2.5V, 4A COMPONENTS, SKIP = GND)
V+ = +7V
90
EFFICIENCY (%)
MAX1715-03
100
V+ = +7V
90
EFFICIENCY (%)
100
100
80
V+ = +7V
EFFICIENCY (%)
60
V+ = +12V
V+ = +12V
80
V+ = +20V
80
V+ = +20V
70
V+ = +12V
40
V+ = +20V
20
70
60
0.01
0.1
1
10
LOAD CURRENT (A)
0
0.01
0.1
1
10
LOAD CURRENT (A)
60
0.01
0.1
1
10
LOAD CURRENT (A)
_______________________________________________________________________________________
5
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