MAX1715 ,Ultra-High-Efficiency, Dual Step-Down Controller for Notebook ComputersELECTRICAL CHARACTERISTICS(Circuit of Figure 1, 4A components from Table 1, V V = +5V, SKIP = AGND, ..
MAX1715 ,Ultra-High-Efficiency, Dual Step-Down Controller for Notebook ComputersApplicationsNotebook Computers5V INPUT BATTERY CPU Core Supply4.5V TO 28VV V+DDChipset/RAM Supply a ..
MAX1715 ,Ultra-High-Efficiency, Dual Step-Down Controller for Notebook ComputersFeaturesThe MAX1715 PWM controller provides the high effi-♦ Ultra-High Efficiencyciency, excellent ..
MAX1715EEI ,Ultra-High Efficiency / Dual Step-Down Controller for Notebook ComputersMAX171519-1541; Rev 0; 1/00Ultra-High Efficiency, Dual Step-DownController for Notebook Computers
MAX1715EEI+ ,Ultra-High-Efficiency, Dual Step-Down Controller for Notebook ComputersFeaturesThe MAX1715 PWM controller provides the high effi-♦ Ultra-High Efficiencyciency, excellent ..
MAX1715EEI+T ,Ultra-High-Efficiency, Dual Step-Down Controller for Notebook ComputersELECTRICAL CHARACTERISTICS(Circuit of Figure 1, 4A components from Table 1, V V = +5V, SKIP = AGND, ..
MAX4544CSA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesApplicationsMAX4541CUA 0°C to +70°C 8 µMAX —Battery-Operated Systems Test EquipmentMAX4541CSA 0 ..
MAX4544CSA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesMAX4541–MAX454419-1202; Rev 3; 8/02Low-Voltage, Single-Supply Dual SPST/SPDT Analog Switches
MAX4544CSA+ ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesMAX4541–MAX454419-1202; Rev 4; 6/07Low-Voltage, Single-Supply Dual SPST/SPDT Analog Switches
MAX4544CUA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesFeaturesThe MAX4541–MAX4544 are precision, dual analog Low R : 60Ω max (33Ω typ)ONswitches design ..
MAX4544CUA+ ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesGeneral Description ________
MAX4544EPA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesGeneral Description ________
MAX1715
Ultra-High-Efficiency, Dual Step-Down Controller for Notebook Computers
General DescriptionThe 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.
ApplicationsNotebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 1V
1.8V and 2.5V I/O Supply
FeaturesUltra-High EfficiencyNo Current-Sense Resistor (lossless ILIMIT)Quick-PWM with 100ns Load-Step Response1% VOUTAccuracy over Line and LoadDual-Mode Fixed 1.8V/3.3V/Adj or 2.5V/Adj OutputsAdjustable 1V to 5.5V Output Range2V to 28V Battery Input Range200/300/420/540kHz Nominal Switching FrequencyOver/Undervoltage Protection1.7ms Digital Soft-StartDrives Large Synchronous-Rectifier FETsPower-Good Indicator
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers19-1541; Rev 2; 8/05
Pin Configuration appears at end of data sheet.Quick-PWM is a trademark of Maxim Integrated Products.
Ordering Information
EVALUATION KIT
AVAILABLEVCC
OUTPUT1
1.8V
BATTERY
4.5V TO 28V
ILIM1
ON2
DL1
TON
OUT1
LX1
DH1
FB1AGND
VDD
BST1
ILIM2
ON1
REF
DL2
PGND
OUT2
LX2
DH2
FB2
BST2
SKIP
5V INPUT
PGOOD
OUTPUT2
2.5V
MAX1715
Minimal Operating Circuit
PARTTEMP RANGEPIN-PACKAGEMAX1715EEI-40°C to +85°C28 QSOP
MAX1715EEI+-40°C to +85°C28 QSOP
+ Denotes lead-free package.
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
ABSOLUTE MAXIMUM RATINGSStresses 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.
V+ to AGND..............................................................-0.3 to +30V
VDD, VCCto AGND..................................................-0.3V to +6V
PGND to AGND or VCCto 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
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 otherwisenoted.) (Note 1)
ILOAD= 0 to 4A, each output%0.4
FB2 = GND
Battery voltage, V+Input Voltage Range
V+ = 24V, OUT2 = 2V
Load Regulation Error
VCC= 4.5V to 5.5V, V+ = 4.5V to 28V
V+ = 24V, OUT1 = 2V
Adjustable mode, each output
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
TON = GND
FB_ Input Bias Current
TON = GND
TON = open
VOUT_ = AGND
CONDITIONS
TON = REF142173205
TON = VDD
OUT_ Input Resistance
Soft-Start Ramp TimeFB_ = AGND
Rising edge of ON_ to full current limit
V+ = 2V to 28V,
SKIP= VCC, TA = +25°C
ILOAD= 0 to 4A
V+ = 2V to 28V,
SKIP= VCC, TA = +25°C
ILOAD= 0 to 4A
On-Time (PWM2)
On-Time (PWM1)
TON = open292336380
TON = REF
75k
3.2673.33.333FB1 = VCC
FB1 = AGND
FB1 = OUT1
FB2 = OUT215.5Output Voltage Range0.2
Line Regulation Error
TON = VDD420484550
UNITSMINTYPMAXPARAMETEROutput 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
4.55.5VDD,VCC
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
3.2503.33.350FB1 = VCC
FB1 = AGND
FB1 = OUT1
FB2 = GND
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)2.4632.52.538
V+ = 2V to 28V,
SKIP= VCC, TA = 0°C to +85°C
ILOAD= 0 to 4A
0.9851.001.105FB2 = OUT2
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, 4A components from Table 1, VCC = VDD= +5V, SKIP= AGND, V+ = 15V, TA
= 0°C to +85°C, unless otherwisenoted.) (Note 1)
(Note 3) ns400500Minimum Off-Time
IREF= 0 to 50µA
No external REF load
ON1 = ON2 = 020.01Reference Load Regulation1.9822.02Reference Voltage<15Shutdown Supply Current (V+)<15Shutdown Supply Current
(VCC+ VDD)
Falling edge, hysteresis = 40mVV1.6REF Fault Lockout Voltage
PGND - LX_, ILIMresistor = 100kΩmV405060Current-Limit Threshold
(Positive Direction, Adjusted)
PGND - LX_, TA= +25°C, ILIM= VCCmV-145-120-95Current-Limit Threshold
(Negative Direction)
PGND - LX_, SKIP= AGNDmV-5310Current-Limit Threshold, Zero
Crossing
Hysteresis = 10°C°C150Thermal Shutdown Threshold
Rising edge, hysteresis = 20mV, PWM disabled below
this levelV4.14.4VCCUndervoltage Lockout
Threshold
BST - LX forced to 5VΩ1.55DH Gate Driver On-Resistance
FB1 and FB2 forced above the regulation pointµA11001600Quiescent Supply Current
(VCC+ VDD)2570Quiescent Battery Current (V+)
FB_ forced 2% above trip threshold µs1.5Overvoltage Fault Propagation
Delay
With respect to error comparator threshold %8.510.513Overvoltage Trip Threshold
With respect to error comparator threshold%607080Output Undervoltage Threshold
From ON_ signal going highms102030Output Undervoltage Lockout
Time
PGND - LX_, ILIM= VCCmV75100125Current-Limit Threshold
(Positive Direction, Fixed)
ON1 = ON2 = 0
DL, high stateΩ1.55DL Gate Driver On-Resistance
(pull-up)
0.62.5DH Gate Driver Source/Sink
Current DH forced to 2.5V, BST_ - LX_ forced to 5V1DL Gate Driver Source CurrentDL forced to 2.5V1DL Gate Driver Sink CurrentDL forced to 2.5V3Dead TimeDL rising35
REF in regulationREF Sink Current
DL, low state DL Gate Driver On-Resistance
(pull-down)Ω
CONDITIONSUNITSMINTYPMAXPARAMETERPGND - LX_, ILIMresistor = 400kΩ160200240
DH rising26
ON_, SKIP0.8Logic Input High VoltageON_, SKIP2.4Logic Input Low Voltage
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
ELECTRICAL CHARACTERISTICS (Circuit of Figure 1, 4A components from Table 1, VCC = VDD= +5V, SKIP= AGND, V+ = 15V, TA
= -40°C to +85°C, unless otherwisenoted.) (Note 1)
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, 4A components from Table 1, VCC = VDD= +5V, SKIP= AGND, V+ = 15V, TA
= 0°C to +85°C, unless otherwisenoted.) (Note 1)
CONDITIONSVCC level
VCC- 0.4
TON ThresholdFloat level3.153.85
REF level1.652.35
AGND level0.5
TON (0 or VCC)µA-33Logic Input Current
UNITSMINTYPMAXPARAMETEROn-Time (PWM1)
FB2 = GND
FB2 = OUT2V+ = 4.5V to 28V,
SKIP= VCC
3.2343.33.372FB1 = VCC
FB1 = AGND
FB1 = OUT1
Minimum Off-Time400500ns(Note 3)
Output 2 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
PARAMETERMINTYPMAXUNITS
Input Voltage Range 228V4.55.5
Output 1 Error Comparator
Threshold (DC Output Voltage
Accuracy) (Note 2)
CONDITIONS
Battery voltage, V+
VDD, VCC
V+ = 2V to 28V,
SKIP= VCC
On-Time (PWM2)
ON_, SKIP(0 or VCC)µA-11Logic Input Current
Falling edge, FB_ forced 2% below PGOOD trip thresholdµs1.5PGOOD Propagation Delay
Measured at FB_, with respect to error comparator
threshold, no load%-8-5.5-4PGOOD Trip Threshold
ISINK= 1mAV0.10.4PGOOD Output Low Voltage
High state, forced to 5.5VµA1PGOOD Leakage Current
SKIP, to deactivate OVP circuitrymA-5-1Logic Input Current
198234270V+ = 24V, OUT2 = 2V
TON = GND
TON = REF
TON = open
TON = VDD
V+ = 24V, OUT1 = 2V
TON = GND
TON = REF
TON = open
TON = VDD
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook ComputersMAX1715-01
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(1.8V, 4A COMPONENTS, SKIP = GND)V+ = +7V
V+ = +12V
V+ = +20V
MAX1715-02
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(1.8V, 4A COMPONENTS, SKIP = VCC)V+ = +7V
V+ = +20V
V+ = +12V
MAX1715-03
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(2.5V, 4A COMPONENTS, SKIP = GND)V+ = +7V
V+ = +20V
V+ = +12V
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, VBST= 5V. Actual
in-circuit times may differ due to MOSFET switching speeds.
__________________________________________Typical Operating Characteristics(Circuit of Figure 1, components from Table 1, VIN= +15V, SKIP= AGND, TON= unconnected, TA= +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, 4A components from Table 1, VCC = VDD= +5V, SKIP= AGND, V+ = 15V, TA
= -40°C to +85°C, unless otherwisenoted.) (Note 1)
Quiescent Battery Current (V+)2570µA
Reference Voltage1.9722.03VNo external REF load
Quiescent Supply Current
(VCC+ VDD)11001600µAFB1 and FB2 forced above the regulation point
PARAMETERMINTYPMAXUNITSCONDITIONSReference Load Regulation0.01VIREF= 0 to 50µA
Overvoltage Trip Threshold1012.515%With respect to error comparator threshold
Output Undervoltage Threshold607080%With respect to error comparator threshold
Current-Limit Threshold (positive
direction, fixed)75100125mVPGND - LX_, ILIM= VCC
Current-Limit Threshold (positive
direction, adjusted)5062
PGND - LX_, ILIMresistor = 100kΩ
PGND - LX_, ILIMresistor = 400kΩ160200240
Thermal Shutdown Threshold150°CHysteresis = 10°C
Rising edge, hysteresis = 20mV, PWM disabled below
this level4.14.4VVCCUndervoltage Lockout
Threshold
Logic Input High Voltage2.4VON_, SKIP
ON_, SKIP0.8VLogic Input Low Voltage
SKIP, to deactivate OVP circuitry-5-1mALogic Input Current
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
_____________________________Typical Operating Characteristics (continued)(Circuit of Figure 1, components from Table 1, VIN= +15V, SKIP= AGND, TON= unconnected, TA= +25°C, unless otherwise noted.)
MAX1715-9
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(1.3V, 8A COMPONENTS, SKIP = VCC)V+ = +7V
V+ = +20V
V+ = +12V
MAX1715-10
LOAD CURRENT (A)
FREQUENCY (kHz)
FREQUENCY vs. LOAD CURRENT
(4A COMPONENTS)OUT1, SKIP = VCC
OUT2, SKIP = VCC
OUT1, SKIP = GND
OUT2, SKIP = GND
MAX1715-11
SUPPLY VOLTAGE (V)
FREQUENCY (kHz)
FREQUENCY vs. SUPPLY VOLTAGE
(4A COMPONENTS, SKIP = VCC)OUT1
OUT2
MAX1715-07
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(3.3V, 1.5A COMPONENTS, VIN = 5V)SKIP = VCC
SKIP = GND
MAX1715-08
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(1.3V, 8A COMPONENTS, SKIP = GND)V+ = +7V
V+ = +20V
V+ = +12V
MAX1715-04
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(2.5V, 4A COMPONENTS, SKIP = VCC)V+ = +7V
V+ = +20V
V+ = +12V
MAX1715-05
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(5V, 3A COMPONENTS, SKIP = GND)V+ = +7V
V+ = +20V
V+ = +12V
MAX1715-06
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(5V, 3A COMPONENTS, SKIP = VCC)V+ = +7V
V+ = +20V
V+ = +12V
MAX1715-12
TEMPERATURE (°C)
FREQUENCY (kHz)
FREQUENCY vs. TEMPERATURE
(2.5V, 4A COMPONENTS, SKIP = HIGH)MAX1715-16
A = VOUT, 2V/div
B = INDUCTOR CURRENT, 2A/div
C = DL, 10V/div
START-UP WAVEFORM
(2.5V, 4A COMPONENTS, ACTIVE LOAD)MAX1715-13
INPUT VOLTAGE (V)
SUPPLY CURRENT (
NO-LOAD SUPPLY CURRENT vs. INPUT VOLTAGE
(OUT1 = 1.8V, 4A COMPONENTS;
OUT2 = 2.5V, 4A COMPONENTS; SKIP = GND)IDD
ICC
IBATT10520152530
MAX1715-14
INPUT VOLTAGE (V)
SUPPLY CURRENT (mA)
NO-LOAD SUPPLY CURRENT vs. INPUT VOLTAGE
(OUT1 = 1.8V, 4A COMPONENTS;
OUT2 = 2.5V, 4A COMPONENTS; SKIP = VCC)IDD
ICC
IIN
MAX1715-17
A = VOUT, AC-COUPLED, 100mV/div
B = INDUCTOR CURRENT, 5A/div
C = DL, 10V/div
LOAD-TRANSIENT RESPONSE
(1.3V, 8A COMPONENTS, SKIP = GND)
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
_____________________________Typical Operating Characteristics (continued)(Circuit of Figure 1, components from Table 1, VIN= +15V, SKIP= AGND, TON= unconnected, TA= +25°C, unless otherwise noted.)
MAX1715-19
A = VOUT, 2V/div
B = INDUCTOR CURRENT, 5A/div
C = DL, 10V/div
SHUTDOWN WAVEFORM
(2.5V, 4A COMPONENTS, SKIP = GND)MAX1715-18
A = VOUT, 2V/div
B = INDUCTOR CURRENT, 5A/div
C = DL, 10V/div
OUTPUT OVERLOAD WAVEFORM
(2.5V, 4A COMPONENTS, SKIP = GND)MAX1715-15
A = VOUT, AC-COUPLED, 100mV/div
B = INDUCTOR CURRENT, 2A/div
C = DL, 10V/div
LOAD-TRANSIENT RESPONSE
(2.5V, 4A COMPONENTS, SKIP = GND)
170
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
Pin DescriptionOUT1 ON/OFFControl Input. Drive to AGND to turn OUT1 off. Drive to VCCto turn OUT1 on.ON110
Feedback Input for OUT1. Connect to AGND for 1.8V fixed output or to VCCfor 3.3V fixed output, or connect
to a resistor-divider from OUT1 for an adjustable output.FB12
+2.0V Reference Voltage Connection. Bypass to AGND with 0.22µF (min) capacitor. Can supply 50µA for
external loads.REF9
Output Voltage Connection for the OUT1 PWM. Connect directly to the junction of the external inductor and
output filter capacitors. OUT1 senses the output voltage to determine the on-time and also serves as the
feedback input in fixed-output modes.
OUT11
Pulse-Skipping Control Input. Connect to VCCfor low-noise forced-PWM mode. Connect to AGND to enable
pulse-skipping operation.SKIP6
Power-Good Open-Drain Output. PGOOD is low when either FB_ input is more than 5.5% below the normal
regulation point (typ).PGOOD7
Analog GroundAGND8
Current-Limit Threshold Adjustment for OUT1. The LX1-PGND current-limit threshold defaults to +100mV if
ILIM1 is connected to VCC. Or, connect an external resistor to AGND to adjust the limit. A precision 5µA pull-up
current through REXTsets the threshold from 50mV to 200mV. The voltage on the pin is 10 times the current-
limit voltage. Choose REXTequal to 2kΩper mV of current-limit threshold (100kΩto 400kΩ).
ILIM13
Battery Voltage Sense Connection. Connect to the input power source. V+ is used only to set the PWM one-
shot timing.V+4
PINOn-Time Selection Control Input. This is a four-level input used to determine DH_ on-time. The TON table
below is for VIN= 24V, VOUT1= 1.8V, VOUT2= 2.5V condition.
TON5
FUNCTIONNAMEOUT2 ON/OFFControl Input. Drive to AGND to turn OUT2 off. Drive to VCCto turn OUT2 on.ON211
Current-Limit Threshold Adjustment for OUT2. The LX2-PGND current-limit threshold defaults to +100mV if
ILIM2 is connected to VCC. Or, connect an external resistor to AGND to adjust the limit. A precision 5µA pull-up
current through REXTsets the threshold from 50mV to 200mV. The voltage on the pin is 10 times the current-
limit voltage. Choose REXTequal to 2kΩper mV of current-limit threshold (100kΩto 400kΩ).
ILIM212
Feedback Input for OUT2. Connect to AGND for 2.5V fixed output, or connect to a resistor-divider from
OUT2 for an adjustable output.FB213
Output Voltage Connection for the OUT2 PWM. Connect directly to the junction of the external inductor and
output filter capacitors. OUT2 senses the output voltage to determine the on-time and also serves as the
feedback input in fixed-output mode.
OUT214
No Connection. These pins are not connected to any internal circuitry. Connect the N.C. pins to the ground
plane to enhance thermal conductivity.N.C.15, 23,
AGND
TONOpen
VCC
REF
235
345
485
620
Frequency (OUT1) (kHz)Frequency (OUT2) (kHz)460
355
255
170
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
Pin Description (continued)High-Side Gate Driver Output for OUT1. Swings from LX1 to BST1.DH126
High-Side Gate Driver Output for OUT2. Swings from LX2 to BST2.DH217
Boost Flying Capacitor Connection for OUT1. Connect to an external capacitor and diode according to the
Standard Application Circuit (Figure 1). See MOSFET Gate Drivers (DH_, DL_)section.BST125
External Inductor Connection for OUT2. Connect to the switched side of the inductor. LX2 serves as the
lower supply voltage rail for the DH2 high-side gate driver and is the positive input to the OUT2 current-limit
comparator.
LX216
Analog-Supply Input. Connect to the system supply voltage, +4.5V to +5.5V, with a 20Ωseries resistor.
Bypass to AGND with a 1µF ceramic capacitor.VCC21
Power Ground. Connect directly to the low-side MOSFETs’ sources. Serves as the negative input of the cur-
rent-sense amplifiers.PGND22
Low-Side Gate Driver Output for OUT1. DL1 swings PGND to VDD.DL124
Boost Flying Capacitor Connection for OUT2. Connect to an external capacitor and diode according to the
Standard Application Circuit (Figure 1). See MOSFET Gate Drivers (DH_, DL_)section.BST218
Low-Side Gate-Driver Output for OUT2. DL2 swings from PGND to VDD.DL219
PINSupply Input for the DL Gate Drivers. Connect to the system supply voltage, +4.5V to +5.5V. Bypass to
PGND with a minimum 4.7µF ceramic capacitor.VDD20
FUNCTIONNAMEExternal Inductor Connection for OUT1. Connect to the switched side of the inductor. LX1 serves as the
lower supply voltage rail for the DH1 high-side gate driver.LX127
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook ComputersVDD = 5V
BIAS SUPPLY
PINS 15, 23, 28 = N.C.
POWER-GOOD
INDICATOR
MAX1715
VCC
OUTPUT1
1.8V
VIN
4.5V TO 28V
CMPSH-3A
ILIM1
ON1
DL1
TON
OUT1
AGNDC4D1N2N4N1
LX1
DH1
0.1μF
0.1μF
0.22μFFB1
VDD
1μF
C11
1μF
BST1
ILIM2
REF
ON1
ON2
DL2
PGND
+5V
100k
OUT2
LX2
DH2
FB2
PGOOD
BST2
SKIP
4.7μF
20Ω
OUTPUT2
2.5V
ON/OFF
CONTROLS
Figure 1. Standard Application Circuit
Standard Application CircuitThe standard application circuit (Figure 1) generates
two low-voltage rails for general-purpose use in note-
book computers (I/O supply, fixed CPU core supply,
DRAM supply). This DC-DC converter steps down a
battery or AC adapter voltage to voltages from 1.0V to
5.5V with high efficiency and accuracy.
See Table 1 for a list of components for common appli-
cations. Table 2 lists component manufacturers.
Detailed DescriptionThe MAX1715 buck controller is designed for low-volt-
age power supplies for notebook computers. Maxim’s
proprietary Quick-PWM pulse-width modulator in the
MAX1715 (Figure 2) is specifically designed for han-
dling fast load steps while maintaining a relatively con-
stant operating frequency and inductor operating point
over a wide range of input voltages. The Quick-PWM
architecture circumvents the poor load-transient timing
problems of fixed-frequency current-mode PWMs while
also avoiding the problems caused by widely varying
switching frequencies in conventional constant-on-time
and constant-off-time PWM schemes.
+5V Bias Supply (VCCand VDD)The MAX1715 requires an external +5V bias supply in
addition to the battery. Typically, this +5V bias supply
is the notebook’s 95% efficient +5V system supply.
Keeping the bias supply external to the IC improves
efficiency and eliminates the cost associated with the
+5V linear regulator that would otherwise be needed to
supply the PWM circuit and gate drivers. If stand-alone
capability is needed, the +5V supply can be generated
with an external linear regulator such as the MAX1615.
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook ComputersThe power input and +5V bias inputs can be connected
together if the input source is a fixed +4.5V to +5.5V
supply. If the +5V bias supply is powered up prior to
the battery supply, the enable signal (ON1, ON2) must
be delayed until the battery voltage is present to ensure
start-up. The +5V bias supply must provide VCCand
gate-drive power, so the maximum current drawn is:
IBIAS= ICC+ f (QG1 + QG2) = 5mA to 30mA (typ)
where ICC is 1mA typical, f is the switching frequency,
and QG1 and QG2 are the MOSFET data sheet total
gate-charge specification limits at VGS= 5V.
Free-Running, Constant-On-Time PWM
Controller with Input Feed-ForwardThe Quick-PWM control architecture is a pseudo-fixed-
frequency, constant-on-time current-mode type with
voltage feed-forward (Figure 3). This architecture relies
on the output filter capacitor’s ESR to act as the cur-
rent-sense resistor, so the output ripple voltage pro-
vides the PWM ramp signal. The control algorithm is
simple: the high-side switch on-time is determined sole-
ly by a one-shot whose period is inversely proportional
to input voltage and directly proportional to output volt-
age. Another one-shot sets a minimum off-time (400ns
typ). The on-time one-shot is triggered if the error com-
parator is low, the low-side switch current is below the
Table 1. Component Selection for Standard Applications
Table 2. Component Suppliers
4.75V to 5.5V7V to 20V7V to 20VInput Range100µF, 10V
Sanyo POSCAP
10TPA100M
470µF, 4V Sanyo
POSCAP 4TPB470M
470µF, 4V Sanyo
POSCAP 4TPB470MC2 Output Capacitor
100µF, 10V
Sanyo POSCAP
10TPA100M
10µF, 25V
Taiyo Yuden
TMK432BJ106KM
10µF, 25V
Taiyo Yuden
TMK432BJ106KM
C1 Input Capacitor
3.3µH
TOKO D73LC
3.1µH
Sumida CDRH125
4.4µH
Sumida CDRH125L1 InductorNihon EP10QY03Nihon EP10QY03D2 Rectifier
International Rectifier
1/2 IRF7301
Fairchild
Semiconductor
1/2 FDS6982A
Fairchild
Semiconductor
1/2 FDS6982A
Q2 Low-Side MOSFET
International Rectifier
1/2 IRF7301
Fairchild
Semiconductor
1/2 FDS6982A
Fairchild
Semiconductor
1/2 FDS6982A
Q1 High-Side MOSFET
600kHz345kHz255kHzFrequency
3.3V at 1.5A1.8V at 4A2.5V at 4ACOMPONENT[1] 602-994-6430602-303-5454Motorola
[1] 408-986-1442408-986-0424Kemet
[1] 408-721-1635408-822-2181Fairchild Semiconductor
[1] 561-241-9339561-241-7876Coiltronics
[1] 847-639-1469847-639-6400Coilcraft
[1] 516-435-1824516-435-1110Central Semiconductor
[1] 803-626-3123803-946-0690AVX
FACTORY FAX
[Country Code]USA PHONEMANUFACTURER[1] 714-960-6492714-969-2491Matsuo
[1] 310-322-3332310-322-3331International Rectifier
[1] 408-573-4159408-573-4150Taiyo Yuden
[1] 603-224-1430603-224-1961Sprague
[1] 408-970-3950408-988-8000
800-554-5565Siliconix
[81] 7-2070-1174619-661-6835Sanyo
[81] 3-3494-7414805-867-2555*NIEC (Nihon)
[1] 814-238-0490814-237-1431
800-831-9172Murata
[81] 3-3607-5144847-956-0666Sumida
[1] 847-390-4405847-390-4461TDK
*Distributor
7V to 20V(2) 470µF, 6V Kemet
T510X477108M0
06AS
(2) 10µF, 25V
Taiyo Yuden
TMK432BJ106KM
1.5µH Sumida
CEP125-1R5MC
Motorola
MBRS340T3
Fairchild
Semiconductor
FDS6670A
International
Rectifier IRF7811
255kHz
1.3V at 8A
7V to 20V330µF, 6V AVX
TPSV337M006R
10µF, 25V
Taiyo Yuden
TMK432BJ106KM
6.8µH
Coiltronics UP2B
Nihon EP10QY03
Fairchild
Semiconductor
1/2 FDS6990A
Fairchild
Semiconductor
1/2 FDS6990A
255kHz
5V at 3A[1] 708-699-1194800-PIK-TOKOTOKO
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computerscurrent-limit threshold, and the minimum off-time one-
shot has timed out.
On-Time One-Shot (TON)The heart of the PWM core is the one-shot that sets the
high-side switch on-time for both controllers. This fast,
low-jitter, adjustable one-shot includes circuitry that
varies the on-time in response to battery and output
voltage. The high-side switch on-time is inversely pro-
portional to the battery voltage as measured by the V+
input, and proportional to the output voltage. This algo-
rithm results in a nearly constant switching frequency
despite the lack of a fixed-frequency clock generator.
The benefits of a constant switching frequency are
twofold: first, the frequency can be selected to avoid
noise-sensitive regions such as the 455kHz IF band;
second, the inductor ripple-current operating point
remains relatively constant, resulting in easy design
methodology and predictable output voltage ripple.
The on-times for side 1 are set 15% higher than the
REF
AGND
REF
OUT2
FB2
20Ω
PGND
VDD
OUTPUT2
2.5V
DL2
VCC
VDD
LX2
ZERO
CROSSING
CURRENT
LIMIT
PWM
CONTROLLER
(SEE FIGURE 3)
DH2
BST2R
ILIM_
VDD
VCC
OUT1
FB1
SKIP
TON
ON1
ON2
OUTPUT1
1.8V
5V INPUT
DL1
VDD
LX1
ZERO
CROSSING
CURRENT
LIMIT
DH1
ILIM_
BATTERY
4.5V TO 28V
5μA
BST1
VDD
VDD
VCCVDD
PWM
CONTROLLER
(SEE FIGURE 3)
MAX1715
5μA
PGOOD
Figure 2. Functional Diagram
MAX1715
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook ComputersREF
-6%
FROM
OUT
REF
FROM ZERO-CROSSING COMPARATOR
ERROR
AMP
TOFF
TON
REF
+12%
REF
-30%
FEEDBACK
MUX
(SEE FIGURE 9)
OVP/UVLO
LATCH
TO DL DRIVER
TO DH DRIVER
ON-TIME
COMPUTE
TON
1-SHOT
FROM ILIM
COMPARATOR
1-SHOT
TRIG
2V TO 28V
TRIG
FB_
OUT_TIMER
TON
TO PGOOD
OR GATE
Figure 3. PWM Controller (one side only)
X = Don’t care
ON1ON2SKIPMODECOMMENTS0XSHUTDOWNLow-power shutdown state. DL = VDD. Clears fault latches.1XOUT1 DisableDisable OUT1. DL1 = VDD. Clears OUT1 fault latches.0XOUT2 DisableDisable OUT2. DL2 = VDD. Clears OUT2 fault latches.X<-0.3VNo FaultDisables the output overvoltage and undervoltage fault circuitry.1VDDRUN (PWM)
Low Noise
Low-Noise operation with no automatic PWM/PFM switchover. Fixed-frequency PWM
action is forced regardless of load. Inductor current reverses at light load levels. IDD
draw <1.5mA (typ) plus gate-drive current.
Table 3. Operating Mode Truth Table1AGNDRUN
(PFM/PWM)
Normal operation with automatic PWM/PFM switchover for pulse-skipping at light loads.
IDD<1.5mA (typ) plus gate drive current.
