MAX1714 ,High-Speed Step-Down Controller for Notebook ComputersApplicationsV VCC DDNotebook ComputersSHDN V+CPU Core SupplyBSTILIMChipset/RAM Supply as Low as 1V ..
MAX17149ETE+T ,Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up ConvertersElectrical Characteristics(Circuit of Figure 1. V = 12V, R = 100kΩ, T = 0°C to +85°C, unless otherw ..
MAX1714A ,High-Speed Step-Down Controller for Notebook ComputersApplicationsV VCC DDNotebook ComputersSHDNV+CPU Core SupplyBSTILIMChipset/RAM Supply as Low as 1V O ..
MAX1714AEEP ,High-Speed Step-Down Controller for Notebook Computersapplications requiring VID compli-ance or DAC control of output voltage, refer to theMAX1710/MAX171 ..
MAX1714AEEP ,High-Speed Step-Down Controller for Notebook Computersapplications requiring VID compli-ance or DAC control of output voltage, refer to theMAX1710/MAX171 ..
MAX1714AEEP ,High-Speed Step-Down Controller for Notebook ComputersMAX171419-1536; Rev 1; 12/99High-Speed Step-Down Controllerfor Notebook Computers
MAX4541EUA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesELECTRICAL CHARACTERISTICS—Single +5V Supply(V+ = +5V ±10%, GND = 0, V = 2.4V, V = 0.8V, T = T to T ..
MAX4541EUA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesMAX4541–MAX454419-1202; Rev 3; 8/02Low-Voltage, Single-Supply Dual SPST/SPDT Analog Switches
MAX4541EUA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesMAX4541–MAX454419-1202; Rev 3; 8/02Low-Voltage, Single-Supply Dual SPST/SPDT Analog Switches
MAX4541EUA ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesFeaturesThe MAX4541–MAX4544 are precision, dual analog Low R : 60Ω max (33Ω typ)ONswitches design ..
MAX4541EUA+ ,Low-Voltage, Single-Supply Dual SPST/SPDT Analog SwitchesELECTRICAL CHARACTERISTICS—Single +5V Supply(V+ = +5V ±10%, GND = 0, V = 2.4V, V = 0.8V, T = T to T ..
MAX4542CSA ,Low-Voltage / Single-Supply Dual SPST/SPDT Analog SwitchesFeaturesThe MAX4541–MAX4544 are precision, dual analog Low R : 60Ω max (33Ω typ)ONswitches design ..
MAX1714
High-Speed Step-Down Controller for Notebook Computers
General DescriptionThe MAX1714 pulse-width modulation (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 or chip-set/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 MAX1714 achieves high efficiency at a reduced
cost by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by an ability to drive very large synchronous-
rectifier MOSFETs.
Single-stage buck conversion allows these devices 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 MAX1714 is intended for CPU core, chipset,
DRAM, or other low-voltage supplies as low as 1V. The
MAX1714A is available in a 20-pin QSOP package and
includes overvoltage protection. The MAX1714B is
available in a 16-pin QSOP package with no overvolt-
age protection. For applications requiring VID compli-
ance or DAC control of output voltage, refer to the
MAX1710/MAX1711 data sheet. For a dual output ver-
sion, refer to the MAX1715†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 Load2.5V/3.3V Fixed or 1V to 5.5V Adjustable Output
Range2V to 28V Battery Input Range200/300/450/600kHz Switching FrequencyOvervoltage Protection (MAX1714A)Undervoltage Protection1.7ms Digital Soft-StartDrives Large Synchronous-Rectifier FETs2V ±1% Reference OutputPower-Good Indicator
MAX1714
High-Speed Step-Down Controller
for Notebook ComputersQuick-PWM is a trademark of Maxim Integrated Products.Future product—contact factory for availability.
Ordering Information
Minimal Operating Circuit
MAX1714
High-Speed 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 (Note 1)..............................................-0.3V to +30V
VDD, VCCto AGND (Note 1).....................................-0.3V to +6V
PGND to AGND (Note 1)...................................................±0.3VSHDN,PGOOD, OUT to AGND (Note 1)..................-0.3V to +6V
ILIM, FB, REF, SKIP,
TON to AGND (Notes 1, 2)....................-0.3V to (VCC+0.3V)
DL to PGND (Note 1)..................................-0.3V to (VDD+0.3V)
BST to AGND (Note 1)...........................................-0.3V to +36V
DH to LX.....................................................-0.3V to (BST +0.3V)
LX to BST..................................................................-6V to +0.3V
REF Short Circuit to AGND.........................................Continuous
Continuous Power Dissipation (TA= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)..........667mW
20-Pin QSOP (derate 9.1mW/°C above +70°C)..........727mW
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
Note 1:For the MAX1714B, AGND and PGND refer to a single pin designated GND.
Note 2:SKIPmay be forced below -0.3V, temporarily exceeding the absolute maximum rating, disabling over/undervoltage fault
detection for the purpose of debugging prototypes (Figure 6). Limit the current drawn to 5mA maximum.
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, VCC= VDD= +5V, SKIP= AGND, TA= 0°C to +85°C, unless otherwise
noted.) (Note 1)
MAX1714
High-Speed Step-Down Controller
for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, VCC= VDD= +5V, SKIP= AGND, TA= 0°C to +85°C, unless otherwise
noted.) (Note 1)
MAX1714
High-Speed Step-Down Controller
for Notebook Computers
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, 4A components from Table 1, V+ = 15V, VCC = VDD= +5V, SKIP= AGND, TA
= -40°C to +85°C, unless other-wise noted.) (Notes 1, 5)
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, 4A components from Table 1, V+ = +15V, VCC= VDD= +5V, SKIP= AGND, TA= 0°C to +85°C, unless otherwise
noted.) (Note 1)
MAX1714
High-Speed Step-Down Controller
for Notebook ComputersEFFICIENCY vs. LOAD CURRENT
(4A COMPONENTS, VOUT = 2.5V, 300kHz)
MAX1714B-01
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(8A COMPONENTS, VOUT = 1.6V, 300kHz)
MAX1714B-02
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
(1.5A COMPONENTS, VOUT = 2.5V,
TON = GND, 600kHz)
MAX1714B-03
LOAD CURRENT (A)
EFFICIENCY (%)
Note 1:For the MAX1714B, AGND and PGND refer to a single pin designated GND.
Note 2:SKIPmay be forced below -0.3V, temporarily exceeding the absolute maximum rating, disabling over/undervoltage fault
detection for the purpose of debugging prototypes (Figure 6). Limit the current drawn to 5mA maximum.
Note 3:When the inductor is in continuous conduction, the output voltage will have a DC regulation level higher than the error-
comparator threshold by 50% of the ripple. In discontinuous conduction (SKIP= AGND, light-loaded), the output voltage
will have a DC regulation level higher than the trip level by approximately 1.5% due to slope compensation.
Note 4:On-time and off-time specifications are measured from 50% point to 50% point at the DH pin with LX = PGND, VBST= 5V,
and a 250pF capacitor connected from DH to LX. Actual in-circuit times may differ due to MOSFET switching speeds.
Note 5:Specifications to -40°C are guaranteed by design, not production tested.
__________________________________________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, V+= +15V, VCC = VDD= +5V, SKIP= AGND, TA
= -40°C to +85°C, unless other-wise noted.) (Notes 1, 5)
MAX1714
High-Speed Step-Down Controller
for Notebook Computers
_____________________________Typical Operating Characteristics (continued)(Circuit of Figure 1, components from Table 1, VIN
MAX1714
High-Speed 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.)
MAX1714
High-Speed Step-Down Controller
for Notebook Computers
Pin Description
MAX1714
High-Speed Step-Down Controller
for Notebook ComputersFigure 1. Standard Application Circuit
Standard Application CircuitThe standard application circuit (Figure 1) generates a
low-voltage rail for general-purpose use in a notebook
computer (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 component selections for com-
mon applications. Table 2 lists component manufacturers.
Detailed DescriptionThe MAX1714 buck controller is targeted for low-voltage
power supplies for notebook computers. Maxim‘s propri-
etary Quick-PWM pulse-width modulator in the MAX1714
is specifically designed for handling fast load steps
while maintaining a relatively constant operating fre-
quency and inductor operating point over a wide range
of input voltages. The Quick-PWM architecture circum-
vents the poor load-transient timing problems of fixed-
frequency current-mode PWMs while also avoiding the
problems caused by widely varying switching frequen-
cies in conventional constant-on-time and constant-off-
time PWM schemes.
MAX1714
+5V Bias Supply (VCCand VDD)The MAX1714 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 effi-
ciency and eliminates the cost associated with the +5V
linear regulator that would otherwise be needed to sup-
ply 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.
The battery and +5V bias inputs can be tied 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 sup-
ply, the enable signal (SHDN) must be delayed until the
battery voltage is present in order to ensure startup. 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 ICCis 600µA typical, f is the switching frequency,
and QG1and QG2are 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-fre-
quency, constant-on-time current-mode type with voltage
feed-forward (Figure 2). This architecture relies on the out-
put filter capacitor’s ESR to act as the current-sense resis-
tor, so the output ripple voltage provides the PWM ramp
signal. The control algorithm is simple: the high-side
switch on-time is determined solely by a one-shot whose
period is inversely proportional to input voltage and direct-
ly proportional to output voltage. Another one-shot sets a
minimum off-time (400ns typical). The on-time one-shot is
triggered if the error comparator is low, the low-side switch
current is below the current-limit threshold, and the mini-
mum off-time one-shot has timed out.
High-Speed Step-Down Controller
for Notebook Computers
Table 1. Component Selection for Standard Applications
Table 2. Component Suppliers
MAX1714
High-Speed Step-Down Controller
for Notebook Computers
On-Time One-Shot (TON)The heart of the PWM core is the one-shot that sets the
high-side switch on-time. 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 proportional to the battery
voltage as measured by the V+ input, and proportional
to the output voltage. This algorithm 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 volt-
age ripple.
On-Time = K (VOUT+ 0.075V) / VIN
Figure 2. MAX1714 Functional Diagram
MAX1714
High-Speed Step-Down Controller
for Notebook Computerswhere K is set by the TON pin-strap connection and
0.075V is an approximation to accommodate for the
expected drop across the low-side MOSFET switch.
One-shot timing error increases for the shorter on-time
settings due to fixed propagation delays; it is approxi-
mately ±12.5% at 600kHz and 450kHz, and ±10% at the
two slower settings. This translates to reduced switching-
frequency accuracy at higher frequencies (Table 5).
Switching frequency increases as a function of load cur-
rent due to the increasing drop across the low-side
MOSFET, which causes a faster inductor-current dis-
charge ramp. The on-times guaranteed in the Electrical
Characteristicsare influenced by switching delays in the
external high-side power MOSFET.
Two external factors that influence switching-frequency
accuracy are resistive drops in the two conduction loops
(including inductor and PC board resistance) and the
dead-time effect. These effects are the largest contribu-
tors to the change of frequency with changing load cur-
rent. The dead-time effect increases the effective
on-time, reducing the switching frequency as one or
both dead times are added to the effective on-time. It
occurs only in PWM mode (SKIP= high) when the induc-
tor current reverses at light or negative load currents.
With reversed inductor current, the inductor’s EMF caus-
es LX to go high earlier than normal, extending the on-
time by a period equal to the low-to-high dead time.
For loads above the critical conduction point, the actual
switching frequency is:
where VDROP1is the sum of the parasitic voltage drops
in the inductor discharge path, including synchronous
rectifier, inductor, and PC board resistances; VDROP2is
the sum of the resistances in the charging path, and tON
is the on-time calculated by the MAX1714.
Automatic Pulse-Skipping SwitchoverIn skip mode (SKIPlow), an inherent automatic
switchover to PFM takes place at light loads. This
switchover is effected by a comparator that truncates the
low-side switch on-time at the inductor current’s zero
crossing. This mechanism causes the threshold between
pulse-skipping PFM and nonskipping PWM operation to
coincide with the boundary between continuous and dis-
continuous inductor-current operation (also known as the
“critical conduction” point; see the Continuous to
Discontinuous Inductor Current Point vs. Input Voltage
graph in the Typical Operating Characteristics). In low-
duty-cycle applications, this threshold is relatively con-
stant, with only a minor dependence on battery voltage.
where K is the on-time scale factor (Table 5). The load-
current level at which PFM/PWM crossover occurs,
ILOAD(SKIP), is equal to 1/2 the peak-to-peak ripple cur-
rent, which is a function of the inductor value (Figure 3).
For example, in the standard application circuit with
K = 3.3µs (Table 5), VOUT= 2.5V, VIN= 15V, and L =
6.8µH, switchover to pulse-skipping operation occurs at
ILOAD= 0.51A or about 1/8 full load. The crossover point
occurs at an even lower value if a swinging (soft-satura-
tion) inductor is used.
The switching waveforms may appear noisy and asyn-
chronous when light loading causes pulse-skipping
operation, but this is a normal operating condition that
results in high light-load efficiency. Trade-offs in PFM
noise vs. light-load efficiency are made by varying the
inductor value. Generally, low inductor values produce a
broader efficiency vs. load curve, while higher values
result in higher full-load efficiency (assuming that the coil
resistance remains fixed) and less output voltage ripple.
Penalties for using higher inductor values include larger
physical size and degraded load-transient response
(especially at low input voltage levels).
DC output accuracy specifications refer to the error-com-
parator threshold of the error comparator. When the
inductor is in continuous conduction, the output voltage
will have a DC regulation level higher than the trip level
by 50% of the ripple. In discontinuous conduction (SKIP
= AGND, light-loaded), the output voltage will have a DC
regulation level higher than the error-comparator thresh-
old by approximately 1.5% due to slope compensation.
Forced-PWM Mode (SKIP= High)The low-noise forced-PWM mode (SKIP= high) disables
the zero-crossing comparator, which controls the low-
side switch on-time. This causes the low-side gate-drive
waveform to become the complement of the high-side
gate-drive waveform. This in turn causes the inductor
current to reverse at light loads while DH maintains a
duty factor of VOUT/VIN. The benefit of forced-PWM
mode is to keep the switching frequency fairly constant,
but it comes at a cost: the no-load battery current can be
10mA to 40mA, depending on the external MOSFETs.
Forced-PWM mode is most useful for reducing audio-
frequency noise, improving load-transient response, pro-
viding sink-current capability for dynamic output voltage
adjustment, and improving the cross-regulation of
