MAX1549ETL ,Dual, Interleaved, Fixed-Frequency Step-Down Controller with a Dynamically Adjustable OutputApplicationsTOP VIEWNotebook Computers40 39 38 37 36 35 34 33 32 31Dynamically Adjustable Chipset S ..
MAX1549ETL+ ,Dual, Interleaved, Fixed-Frequency Step-Down Controller with a Dynamically Adjustable OutputApplicationsTOP VIEWNotebook Computers40 39 38 37 36 35 34 33 32 31Dynamically Adjustable Chipset S ..
MAX1549ETL+T ,Dual, Interleaved, Fixed-Frequency Step-Down Controller with a Dynamically Adjustable Outputfeatures differential current-sense inputsPower-Good and Fault Blanking Duringfor accurately sensin ..
MAX1549ETL+T ,Dual, Interleaved, Fixed-Frequency Step-Down Controller with a Dynamically Adjustable OutputELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = V = 5V, SKIP = GND, T = 0°C to +85°C, unless ot ..
MAX154ACNG ,CMOS High-Speed 8-Bit ADCs with Multiplexer and ReferenceELECTRICAL CHARACTERISTICS(V = +5V, V = +5V, V = GND, Mode 0, T = T to T , unless otherwise noted). ..
MAX154ACNG+ ,CMOS High-Speed, 8-Bit ADCs with Multiplexer and ReferenceApplications24 NarrowMAX154BCNG 0°C to +70°C ±1Plastic DIPDigital Signal Processing1MAX154BC/D 0°C ..
MAX4198EUA ,Micropower / Single-Supply / Rail-to-Rail Precision Differential AmplifiersMAX4198/MAX419919-1445; Rev 0; 4/99Micropower, Single-Supply, Rail-to-RailPrecision Differential Am ..
MAX4198EUA ,Micropower / Single-Supply / Rail-to-Rail Precision Differential AmplifiersELECTRICAL CHARACTERISTICS—MAX4198 (+5V Supply)(V = +5V, V = 0V, R = 25kΩ tied to V / 2, V = V / 2, ..
MAX4198EUA ,Micropower / Single-Supply / Rail-to-Rail Precision Differential AmplifiersELECTRICAL CHARACTERISTICS—MAX4198 (+5V Supply)(V = +5V, V = 0V, R = 25kΩ tied to V / 2, V = V / 2, ..
MAX4198EUA+ ,Micropower, Single-Supply, Rail-to-Rail Precision Differential AmplifiersApplicationsPIN- GAINPART TEMP RANGEInstrumentation Amplifier Building BlockPACKAGE (V/V)Differenti ..
MAX4199ESA ,Micropower / Single-Supply / Rail-to-Rail Precision Differential AmplifiersELECTRICAL CHARACTERISTICS—MAX4198 (+5V Supply) (continued)(V = +5V, V = 0V, R = 25kΩ tied to V / 2 ..
MAX4199EUA ,Micropower / Single-Supply / Rail-to-Rail Precision Differential AmplifiersApplications PIN- GAINPART TEMP. RANGEPACKAGE (V/V)Instrumentation Amplifier Building BlockMAX4198E ..
MAX1549ETL
Dual, Interleaved, Fixed-Frequency Step-Down Controller with a Dynamically Adjustable Output
General DescriptionThe MAX1549 dual pulse-width modulation (PWM) step-
down controller provides the high efficiency, excellent
transient response, and high DC-output accuracy nec-
essary for generating low-voltage chipset and RAM
power supplies in notebook computers. The controller
employs a fixed-frequency, current-mode PWM archi-
tecture that does not require complex compensation.
The MAX1549 also interleaves the dual step-down regu-
lators, minimizing the input capacitor requirements.
The MAX1549 features differential current-sense inputs
for accurately sensing the inductor current across an
external current-sense resistor in series with the output
to ensure reliable overload protection. Alternatively, the
controller can provide overload protection using loss-
less inductor current-sensing methods, lowering power
dissipation and reducing system cost.
Single-stage buck conversion allows the MAX1549 to
directly step down high-voltage batteries for the highest
possible efficiency. Very low output-voltage applica-
tions require two-stage conversion—stepping down
from another system supply rail instead of the battery.
The MAX1549 powers chipsets and graphics processor
cores that require dynamically adjustable output voltages,
or generates the active termination bus that must track
the input reference. The main step-down controller
(OUT1) regulates the dedicated reference input (REFIN)
voltage generated by a resistive voltage-divider from the
MAX1549’s reference. The MAX1549 also includes inter-
nal open-drain pulldowns with logic-level control inputs to
dynamically adjust the REFIN resistive-divider ratio. When
a transition occurs on these control inputs, the controller
enters forced-PWM mode and blanks the power-good
(PGOOD1) output and output fault protection. OUT2 uses
a Dual-Mode™ feedback input to provide either fixed
2.5V/1.8V or adjustable output voltage regulation. The
MAX1549 is available in a 40-pin, 6mm x 6mm thin QFN
package.
ApplicationsNotebook Computers
Dynamically Adjustable Chipset Supplies
Video/GPU Core Supplies
DDR Memory Termination
CPU Core or VCCSupplies
Fixed Chipset/RAM Supplies
Active Termination Buses
FeaturesInterleaved, Fixed-Frequency, Current-Mode
Control Architecture1% VOUTAccuracy Over Line and LoadMain Output (OUT1)
0.5V to 2.0V Adjustable Output
External Reference Input for Dynamically
Selectable Output Voltages
Four Digitally Selectable Output Voltages
Power-Good and Fault Blanking During
TransitionsSecond Output (OUT2)
2.5V/1.8V Fixed or 0.5V to 2.7V Adjustable
OutputAccurate Differential Current-Sense Inputs100kHz/200kHz/300kHz/400kHz Selectable
Switching FrequencyOutput Overvoltage/Undervoltage ProtectionSoft-Start and Soft-ShutdownDrives Large Synchronous-Rectifier FETs2V ±0.6% Reference OutputSeparate Enable Inputs with Accurate Threshold
VoltagesSeparate Power-Good Window Comparators
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
Pin Configuration
Ordering InformationDual Mode is a trademark of Maxim Integrated Products, Inc.
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuit of Figure1, VCC= VDD= 5V, SKIP= GND, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°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.
VCCto GND..............................................................-0.3V to +6V
VDDto PGND............................................................-0.3V to +6V
CSH_, CSL_, OUT_, PGOOD_,
OD_ to GND...........................................-0.3V to (VCC+ 0.3V)
G0, G1, ILIM_, REFIN to GND..................................-0.3V to +6V
FB2, SKIP, ON_ to GND...........................................-0.3V to +6V
REF, CC1, FBLANK, FSEL to GND.............-0.3V to (VCC+ 0.3V)
DL1, DL2 to PGND.....................................-0.3V to (VDD+ 0.3V)
BST1, BST2 to PGND.............................................-0.3V to +36V
LX1 to BST1..............................................................-6V to +0.3V
DH1 to LX1..............................................-0.3V to (VBST1 + 0.3V)
LX2 to BST2..............................................................-6V to +0.3V
DH2 to LX2..............................................-0.3V to (VBST2 + 0.3V)
GND to PGND.......................................................-0.3V to +0.3V
REF Short Circuit to GND...........................................Continuous
Continuous Power Dissipation (TA= +70°C)
40-Pin 6mm x 6mm Thin QFN (derated 26.3mW/°C
above +70°C).............................................................2105mW
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
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
ELECTRICAL CHARACTERISTICS (continued)
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
ELECTRICAL CHARACTERISTICS (continued)Idle Mode is a trademark of Maxim Integrated Products, Inc.
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
ELECTRICAL CHARACTERISTICS (continued)
ELECTRICAL CHARACTERISTICS
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
ELECTRICAL CHARACTERISTICS (continued)
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure1, VCC= VDD= 5V, SKIP= GND, TA
= -40°C to +85°C, unless otherwise noted.) (Note 4)
Note 1:When the inductor is in continuous conduction, the output voltage has a DC regulation level lower than the error-comparator
threshold by 50% of the ripple. In discontinuous conduction (SKIP= GND, light load), the output voltage has a DC regula-
tion level higher than the trip level by approximately 1.5% due to slope compensation.
Note 2:The MAX1549 cannot operate over all combinations of frequency, input voltage (VIN), and output voltage. For large input-to-
output differentials and high switching-frequency settings, the required on-time may be too short to maintain the regulation
specifications. Under these conditions, a lower operating frequency must be selected. The minimum on-time must be
greater than 150ns, regardless of the selected switching frequency. On-time and off-time specifications are measured from
the 50% point to the 50% point at the DH_ pin with LX_ = GND, VBST_= 5V, and a 250pF capacitor connected from DH_ to
LX_. Actual in-circuit times may differ due to MOSFET switching speeds.
Note 3:Specifications are guaranteed by design, not production tested.
Note 4:Specifications to -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics(MAX1549 circuit of Figure1, VIN = 12V, VDD= VCC= 5V, SKIP= GND, FSEL = open, TA= +25°C, unless otherwise noted.)
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
Typical Operating Characteristics (continued)(MAX1549 circuit of Figure1, VIN = 12V, VDD= VCC= 5V, SKIP= GND, FSEL = open, TA= +25°C, unless otherwise noted.)
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
Typical Operating Characteristics (continued)(MAX1549 circuit of Figure1, VIN = 12V, VDD= VCC= 5V, SKIP= GND, FSEL = open, TA= +25°C, unless otherwise noted.)
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
Typical Operating Characteristics (continued)(MAX1549 circuit of Figure1, VIN = 12V, VDD= VCC= 5V, SKIP= GND, FSEL = open, TA= +25°C, unless otherwise noted.)
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
Pin Description (continued)
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
Table 1. Component Selection for Standard Applications
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
Table 2. Component Suppliers
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable OutputFigure 1. Standard Applications Circuit
Detailed DescriptionThe MAX1549 dual fixed-frequency step-down con-
troller designed for low-voltage power supplies is ideal
for graphic processor units (GPUs). The Standard
Applications Circuit(Figure 1) generates the dynami-
cally adjustable output voltage (OUT1) typically
required by graphics processor cores, and a fixed 2.5V
output (OUT2) for the local memory used by the GPU.
The MAX1549 main output supports up to four output
voltages that can be dynamically selected for support-
ing multiple GPU frequency and sleep states. The inter-
leaved, fixed-frequency architecture provides 180°
out-of-phase operation to reduce the input capacitance
required to meet the RMS input-current ratings.
Each controller consists of a multi-input PWM compara-
tor, high-side and low-side gate drivers, fault protection,
power-good detection, adjustable current-limit circuitry,
soft-start, and shutdown logic. The main PWM controller
(OUT1) also includes a dedicated reference input; logic-
selected, open-drain outputs for dynamically adjusting
the output voltage; and an integrator output for improved
output-voltage accuracy. The second PWM controller
(OUT2) includes a dual-mode feedback network and a
multiplexer for preset 2.5V (FB2 = GND), 1.8V (FB2 =
VCC), or adjustable output-voltage operation.
See Table 1 for the standard applications circuit’s com-
ponent selection and Table 2 for component manufac-
turer contact information.
+5V Bias Supply (VCCand VDD)The MAX1549 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, generate the 5V bias supply with
an external linear regulator (VIN> 5.5V) or regulated
charge pump (VIN< 4.5V).
The 5V bias supply must provide VCC(PWM controller)
and VDD(gate-drive power), so the maximum current
drawn is:
IBIAS= ICC+ fSW(QG(LOW)+ QG(HIGH))
= 5mA to 50mA (typ)
where ICCis 1mA (typ), fSWis the switching frequency,
and QG(LOW)and QG(HIGH)are the MOSFET data
sheet’s total gate-charge specification limits at VGS= 5V.
The battery input (VIN) and 5V bias inputs (VCCand
VDD) can be connected together if the input source is a
fixed 4.5V to 5.5V supply. If the 5V bias supply powers
up prior to the battery supply, the enable signals (ON1
and ON2 going from low to high) must be delayed until
the battery voltage is present to ensure startup.
Fixed-Frequency, Current-Mode
PWM ControllerThe heart of each current-mode PWM controller is a
multi-input, open-loop comparator that sums two sig-
nals: the output-voltage error signal with respect to the
reference voltage and the slope-compensation ramp
(Figure 3). The MAX1549 uses a direct-summing config-
uration, approaching ideal cycle-to-cycle control over
the output voltage without a traditional error amplifier
and the phase shift associated with it. The MAX1549
uses a relatively low loop gain, allowing the use of low-
cost output capacitors. The low loop gain results in the
0.1% (typ) load-regulation error and helps reduce the
output-capacitor size and cost by shifting the unity-gain
crossover frequency to a lower level.
Integrator Amplifier (OUT1 Only)A feedback amplifier forces the DC average of the feed-
back voltage to equal the reference threshold voltage.
This transconductance amplifier integrates the feedback
voltage and provides a fine adjustment to the regulation
voltage (Figure 2), allowing accurate DC output voltage
regulation regardless of the output voltage ripple. The
feedback amplifier has the ability to shift the output volt-
age by ±8%. The differential input voltage range is at
least ±80mV total, including DC offset and AC ripple. Use
a capacitor value of 47pF to 1000pF (470pF typ).
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
MAX1549
Dual, Interleaved, Fixed-Frequency Step-Down
Controller with a Dynamically Adjustable Output
