19-1541; Rev 2; 8/05
KIT
ATION
EVALU
LE
B
A
IL
A
AV
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
Features
The MAX1715 PWM controller provides the high efficiency, excellent transient response, and high DC output 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.
♦ Ultra-High Efficiency
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 synchronousrectifier 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 minimum possible physical size.
♦ 200/300/420/540kHz Nominal Switching Frequency
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.
♦ No Current-Sense Resistor (lossless ILIMIT)
♦ Quick-PWM with 100ns Load-Step Response
♦ 1% VOUT 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
♦ Over/Undervoltage Protection
♦ 1.7ms Digital Soft-Start
♦ Drives Large Synchronous-Rectifier FETs
♦ Power-Good Indicator
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX1715EEI
PART
-40°C to +85°C
28 QSOP
MAX1715EEI+
-40°C to +85°C
28 QSOP
+ Denotes lead-free package.
Minimal Operating Circuit
Applications
Notebook Computers
CPU Core Supply
5V INPUT
Chipset/RAM Supply as Low as 1V
V+
VCC
1.8V and 2.5V I/O Supply
MAX1715
ILIM1
ILIM2
ON1
ON2
OUTPUT1
1.8V
Pin Configuration appears at end of data sheet.
BATTERY
4.5V TO 28V
VDD
BST1
BST2
DH1
DH2
LX1
LX2
DL1
DL2
TON
PGND
OUTPUT2
2.5V
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.
MAX1715
General Description
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
ABSOLUTE MAXIMUM RATINGS
V+ to AGND..............................................................-0.3 to +30V
VDD , VCC to AGND ..................................................-0.3V to +6V
PGND to AGND or VCC to VDD ...........................................±0.3V
PGOOD, OUT_ to AGND..........................................-0.3V to +6V
ILIM_, FB_, REF, SKIP, TON,
ON_ to AGND ...........................................-0.3V to (VDD + 0.3V)
DL_ to PGND ..............................................-0.3V to (VDD + 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 (TA = +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, VCC = VDD = +5V, SKIP = AGND, V+ = 15V, TA = 0°C to +85°C, unless otherwise
noted.) (Note 1)
PARAMETER
Input Voltage Range
MIN
Battery voltage, V+
VDD, VCC
TYP
MAX
2
28
4.5
5.5
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = VCC, TA = +25°C
ILOAD = 0 to 4A
FB1 = OUT1
0.99
1.00
1.01
FB1 = AGND
1.782
1.8
1.818
FB1 = VCC
3.267
3.3
3.333
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = VCC, TA = 0°C to +85°C
ILOAD = 0 to 4A
FB1 = OUT1
0.985
1.00
1.105
FB1 = AGND
1.773
1.8
1.827
FB1 = VCC
3.250
3.3
3.350
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = VCC, TA = +25°C
ILOAD = 0 to 4A
FB2 = OUT2
0.99
1.00
1.01
FB2 = GND
2.475
2.5
2.525
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = VCC, TA = 0°C to +85°C
ILOAD = 0 to 4A
FB2 = OUT2
0.985
1.00
1.105
FB2 = GND
2.463
2.5
2.538
Load Regulation Error
ILOAD = 0 to 4A, each output
0.4
Line Regulation Error
VCC = 4.5V to 5.5V, V+ = 4.5V to 28V
0.2
Output Voltage Range
Adjustable mode, each output
OUT_ Input Resistance
FB_ = AGND
75k
FB_ Input Bias Current
VOUT_ = AGND
-0.1
Soft-Start Ramp Time
Rising edge of ON_ to full current limit
On-Time (PWM1)
On-Time (PWM2)
2
CONDITIONS
V+ = 24V, OUT1 = 2V
V+ = 24V, OUT2 = 2V
UNITS
V
V
V
V
V
1
%
%
5.5
V
0.1
µA
Ω
1.7
ms
TON = GND
112
136
160
TON = REF
142
173
205
TON = open
210
247
280
TON = VDD
300
353
407
TON = GND
154
182
215
TON = REF
198
234
270
TON = open
292
336
380
TON = VDD
420
484
550
_______________________________________________________________________________________
ns
ns
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
(Circuit of Figure 1, 4A components from Table 1, VCC = VDD = +5V, SKIP = AGND, V+ = 15V, TA = 0°C to +85°C, unless otherwise
noted.) (Note 1)
PARAMETER
Minimum Off-Time
CONDITIONS
MIN
(Note 3)
Quiescent Battery Current (V+)
TYP
MAX
UNITS
400
500
ns
25
70
µA
1100
1600
µA
Quiescent Supply Current
(VCC + VDD)
FB1 and FB2 forced above the regulation point
Shutdown Supply Current
(VCC + VDD)
ON1 = ON2 = 0