MAX1715.pdf

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19-1541; Rev 1; 5/00
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
General Description
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.
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
Over/Undervoltage Protection
1.7ms Digital Soft-Start
Drives Large Synchronous-Rectifier FETs
Power-Good Indicator
Ordering Information
PART
MAX1715EEI
TEMP. RANGE
PIN-PACKAGE
28 QSOP
-40°C to +85°C
Applications
Minimal Operating Circuit
Notebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 1V
1.8V and 2.5V I/O Supply
5V INPUT
BATTERY
4.5V TO 28V
V DD
V+
V CC
MAX1715
ILIM1
ILIM2
ON1
ON2
BST1
BST2
OUTPUT1
1.8V
DH1
DH2
OUTPUT2
2.5V
Pin Configuration appears at end of data sheet.
LX1
LX2
DL1
DL2
TON
OUT1
PGND
OUT2
PGOOD
REF
SKIP
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.
200/300/420/540kHz Nominal Switching Frequency
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Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
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
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Range
Battery voltage, V+
2
28
V
V DD, V CC
4.5
5.5
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = V CC , T A = +25°C
I LOAD = 0 to 4A
FB1 = OUT1
0.99
1.00
1.01
FB1 = AGND
1.782
1.8
1.818
V
FB1 = V CC
3.267
3.3
3.333
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = V CC , T A = 0°C to +85°C
I LOAD = 0 to 4A
FB1 = OUT1
0.985
1.00
1.105
FB1 = AGND
1.773
1.8
1.827
V
FB1 = V CC
3.250
3.3
3.350
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = V CC , T A = +25°C
I LOAD = 0 to 4A
FB2 = OUT2
0.99
1.00
1.01
V
FB2 = GND
2.475
2.5
2.525
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 2V to 28V,
SKIP = V CC , T A = 0°C to +85°C
I LOAD = 0 to 4A
FB2 = OUT2
0.985
1.00
1.105
V
FB2 = GND
2.463
2.5
2.538
Load Regulation Error
I LOAD = 0 to 4A, each output
0.4
%
Line Regulation Error
V CC = 4.5V to 5.5V, V+ = 4.5V to 28V
0.2
%
Output Voltage Range
Adjustable mode, each output
1
5.5
V
OUT_ Input Resistance
FB_ = AGND
75k
Ω
FB_ Input Bias Current
V OUT _ = AGND
-0.1
0.1
µA
Soft-Start Ramp Time
Rising edge of ON_ to full current limit
1.7
ms
TON = GND
112
136
160
On-Time (PWM1)
V+ = 24V, OUT1 = 2V
TON = REF
142
173
205
ns
TON = open
210
247
280
TON = V DD
300
353
407
TON = GND
154
182
215
On-Time (PWM2)
V+ = 24V, OUT2 = 2V
TON = REF
198
234
270
ns
TON = open
292
336
380
TON = V DD
420
484
550
2 _______________________________________________________________________________________
323064313.080.png
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
CONDITIONS
MIN
TYP
MAX
UNITS
Minimum Off-Time
(Note 3)
400
500
ns
Quiescent Battery Current (V+)
25
70
µA
Quiescent Supply Current
(V CC + V DD )
FB1 and FB2 forced above the regulation point
1100
1600
µA
Shutdown Supply Current
(V CC + V DD )
ON1 = ON2 = 0
<1
5
µA
Shutdown Supply Current (V+)
ON1 = ON2 = 0
<1
5
µA
Reference Voltage
No external REF load
1.98
2
2.02
V
Reference Load Regulation
I REF = 0 to 50µA
2
0.01
V
REF Sink Current
REF in regulation
10
µA
REF Fault Lockout Voltage
Falling edge, hysteresis = 40mV
1.6
V
Overvoltage Trip Threshold
With respect to error comparator threshold
8.5
10.5
13
%
Overvoltage Fault Propagation
Delay
FB_ forced 2% above trip threshold
1.5
µs
Output Undervoltage Threshold
With respect to error comparator threshold
60
70
80
%
Output Undervoltage Lockout
Time
From ON_ signal going high
10
20
30
ms
Current-Limit Threshold
(Positive Direction, Fixed)
PGND - LX_, I LIM = V CC
75
100
125
mV
Current-Limit Threshold
(Positive Direction, Adjusted)
PGND - LX_, I LIM resistor = 100k
Ω
40
50
60
mV
PGND - LX_, I LIM resistor = 400k
Ω
160
200
240
Current-Limit Threshold
(Negative Direction)
PGND - LX_, T A = +25°C, I LIM = V CC
-145
-120
-95
mV
Current-Limit Threshold, Zero
Crossing
PGND - LX_, SKIP = AGND
-5
3
10
mV
Thermal Shutdown Threshold
Hysteresis = 10°C
150
°C
V CC Undervoltage Lockout
Threshold
Rising edge, hysteresis = 20mV, PWM disabled below
this level
4.1
4.4
V
DH Gate Driver On-Resistance
BST - LX forced to 5V
1.5
5
Ω
DL Gate Driver On-Resistance
(pull-up)
DL, high state
1.5
5
Ω
DL Gate Driver On-Resistance
(pull-down)
DL, low state
0.6
2.5
Ω
DH Gate Driver Source/Sink
Current
DH forced to 2.5V, BST_ - LX_ forced to 5V
1
A
DL Gate Driver Source Current
DL forced to 2.5V
1
A
DL Gate Driver Sink Current
DL forced to 2.5V
3
A
Dead Time
DL rising
35
ns
DH rising
26
Logic Input High Voltage
ON_, SKIP
2.4
V
Logic Input Low Voltage
ON_, SKIP
0.8
V
_______________________________________________________________________________________ 3
323064313.081.png
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
CONDITIONS
MIN
TYP
MAX
UNITS
Logic Input Current
SKIP, to deactivate OVP circuitry
-5
-1
mA
V CC level
V CC - 0.4
TON Threshold
Float level
3.15
3.85
V
REF level
1.65
2.35
AGND level
0.5
Logic Input Current
TON (0 or V CC )
-3
3
µA
Logic Input Current
ON_, SKIP (0 or V CC )
-1
1
µA
PGOOD Trip Threshold
Measured at FB_, with respect to error comparator
threshold, no load
-8
-5.5
-4
%
PGOOD Propagation Delay
Falling edge, FB_ forced 2% below PGOOD trip threshold
1.5
µs
PGOOD Output Low Voltage
I SINK = 1mA
0.1
0.4
V
PGOOD Leakage Current
High state, forced to 5.5V
1
µA
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
CONDITIONS
MIN
TYP
MAX UNITS
Input Voltage Range
Battery voltage, V+
V DD, V CC
2
28
V
4.5
5.5
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
FB1 = OUT1
0.98
1.00
1.02
V+ = 2V to 28V,
SKIP = V CC
FB1 = AGND
1.764
1.8
1.836
V
FB1 = V CC
3.234
3.3
3.372
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
V+ = 4.5V to 28V,
SKIP = V CC
FB2 = OUT2
0.98
1.00
1.02
V
FB2 = GND
2.45
2.5
2.55
TON = GND
TON = REF
TON = open
TON = V DD
112
136
160
On-Time (PWM1)
V+ = 24V, OUT1 = 2V
142
173
205
ns
210
247
280
300
353
407
TON = GND
TON = REF
TON = open
TON = V DD
154
182
215
On-Time (PWM2)
V+ = 24V, OUT2 = 2V
198
234
270
ns
292
336
380
420
484
550
Minimum Off-Time
(Note 3)
400
500
ns
4 _______________________________________________________________________________________
323064313.082.png
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
CONDITIONS
MIN
TYP
MAX UNITS
Quiescent Battery Current (V+)
25
70
µA
Quiescent Supply Current
(V CC + V DD )
FB1 and FB2 forced above the regulation point
1100
1600
µA
Reference Voltage
No external REF load
1.97
2
2.03
V
Reference Load Regulation
I REF = 0 to 50µA
0.01
V
Overvoltage Trip Threshold
With respect to error comparator threshold
10
12.5
15
%
Output Undervoltage Threshold
With respect to error comparator threshold
60
70
80
%
Current-Limit Threshold (positive
direction, fixed)
PGND - LX_, I LIM = V CC
75
100
125
mV
Current-Limit Threshold (positive
direction, adjusted)
PGND - LX_, I LIM resistor = 100k Ω
32
50
62
mV
PGND - LX_, I LIM resistor = 400k Ω
160
200
240
Thermal Shutdown Threshold
Hysteresis = 10°C
Rising edge, hysteresis = 20mV, PWM disabled below
this level
150
°C
V CC Undervoltage Lockout
Threshold
Logic Input High Voltage
4.1
4.4
V
ON_, SKIP
ON_, SKIP
2.4
V
Logic Input Low Voltage
0.8
V
Logic Input Current
SKIP, to deactivate OVP circuitry
-5
-1
mA
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 CURR ENT
(1.8V, 4A COMPONENTS, SKIP = GND)
EFFICIENCY vs. LOAD CURR ENT
(1.8V, 4A COMPONENTS, SKIP = V CC )
EFFICIENCY vs. LOAD CURR ENT
(2.5V, 4A COMPONENTS, SKIP = GND)
100
100
100
V+ = +7V
V+ = +7V
80
90
90
V+ = +7V
60
V+ = +12V
V+ = +12V
80
V+ = +12V
80
V+ = +20V
V+ = +20V
40
V+ = +20V
70
20
70
60
0
60
0.01
0.1
1
10
0.01
0.1
1
10
0.01
0.1
1
10
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
_______________________________________________________________________________________ 5
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