MAX8598ETE ,4.5 V to 28 V, low-dropout, wide-input-voltage, step-down controllerApplications15 14 13 1211Nonisolated Power ModulesILIM 16 10 VLVariable-Speed DC Fan Power Supplies ..
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MAX859CPA ,3.3V/5V or Adjustable Output, Step-Up DC-DC ConvertersMAX856–MAX85919-0211; Rev 4; 5/963.3V/5V or Adjustable-Output, Step-Up DC-DC Converters____________ ..
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MB84VD22181FM-70PBS , 32M (X16) FLASH MEMORY & 4M (X16) STATIC RAM
MB84VD22182EE-90 ,32M (x 8/x16) FLASH MEMORY & 4M (x 8/x16) STATIC RAMFUJITSU SEMICONDUCTORDS05-50204-2EDATA SHEETStacked MCP (Multi-Chip Package) FLASH MEMORY & SRAMCMO ..
MAX8598ETE
4.5 V to 28 V, low-dropout, wide-input-voltage, step-down controller
General DescriptionThe MAX8597/MAX8598/MAX8599 voltage-mode PWM
step-down controllers are designed to operate from a
4.5V to 28V input supply and generate output voltages
down to 0.6V. A proprietary switching algorithm stretch-
es the duty cycle to >99.5% for low-dropout design.
Unlike conventional step-down regulators using a p-
channel high-side MOSFET to achieve high duty cycle,
the MAX8597/MAX8598/MAX8599 drive n-channel
MOSFETs resulting in high efficiency and high-current-
capability designs.
The MAX8597 is available in a 20-pin thin QFN pack-
age and is designed for applications that use an analog
signal to control the output voltage with an adjustable
offset, such as DC fan-speed control. This is achieved
with an internal uncommitted operational amplifier. The
MAX8597 is also targeted for tracking output-voltage
applications for chipsets, ASIC and DSP cores, and I/O
supplies. The MAX8598/MAX8599 are available in a 16-
pin thin QFN package and do not have the uncommitted
operational amplifier, reference input, and reference out-
put, but offer an open-drain, power-OK output.
The MAX8597/MAX8598/MAX8599 allow startup with
prebias voltage on the output for applications where a
backup supply or a tracking device may charge the
output capacitor before the MAX8597/MAX8598/
MAX8599 are enabled. In addition, the MAX8599 fea-
tures output overvoltage protection.
These controllers also feature lossless high-side peak
inductor current sensing, adjustable current limit, and
hiccup-mode short-circuit protection. Switching fre-
quency is set with an external resistor from 200kHz to
1.4MHz. This wide frequency range combined with a
wide-bandwidth error amplifier enables the loop com-
pensation scheme to give the user ample flexibility to
optimize for cost, size, and efficiency.
ApplicationsNonisolated Power Modules
Variable-Speed DC Fan Power Supplies
(MAX8597)
Tracking Power Supplies (MAX8597)
Chipset Power Supplies
FeaturesLow Dropout with >99.5% Duty CycleLossless High-Side Current LimitWide 4.5V to 28V Input RangeDynamic Output Voltage Adjustment with
Adjustable Offset (MAX8597)Remote Voltage Sensing for Both Positive and
Negative Rails (MAX8597)Tracking Output Through REFIN (MAX8597)Adjustable Switching Frequency from 200kHz to
1.4MHzAdjustable Soft-StartPrebias StartupEnable and Power-OK (MAX8598/MAX8599) for
Flexible Sequencing25MHz Error AmplifierAdjustable Hiccup Current Limit for Output
Short-Circuit ProtectionOutput Overvoltage Protection (MAX8599)Small, Low-Profile Thin QFN Package
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
Pin Configurations
Ordering Information+Denotes lead-free package.
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VV+= VVL= VAVL= VEN= VREFIN= 5V, VBST= 6V, VLX= 1V, CVL= 4.7µF, CREFOUT= 1µF, VAIN-= VAOUT, VAIN+= 2.5V, VILIM=
VLX- 0.2V, VFB= 0.65V, GND = PGND = 0V, CSS= 0.01µF, RFREQ= 20kΩ, TA
= 0°C to +85°C, typical values are at TA= +25°C,
unless otherwise noted.)
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.
V+, ILIM to GND.....................................................-0.3V to +30V
AVL, VL to GND........................................................-0.3V to +6V
PGND to GND.......................................................-0.3V to +0.3V
FB, EN, POK, AIN-, AIN+, REFIN to GND................-0.3V to +6V
AOUT, REFOUT, FREQ, SS, COMP to
GND .....................................................-0.3V to (VAVL+ 0.3V)
BST to GND............................................................-0.3V to +36V
DH to LX....................................................-0.3V to (VBST+ 0.3V)
LX to GND........................-2V (-2.5V for less than 50ns) to +30V
LX to BST..................................................................-6V to +0.3V
DL to PGND.................................................-0.3V to (VVL+ 0.3V)
Continuous Power Dissipation
16- or 20-Pin Thin QFN
Up to +70°C (derate 16.9mW/°C above +70°C)........1349mW
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
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
ELECTRICAL CHARACTERISTICS (continued)(VV+= VVL= VAVL= VEN= VREFIN= 5V, VBST= 6V, VLX= 1V, CVL= 4.7µF, CREFOUT= 1µF, VAIN-= VAOUT, VAIN+= 2.5V, VILIM=
VLX- 0.2V, VFB= 0.65V, GND = PGND = 0V, CSS= 0.01µF, RFREQ= 20kΩ, TA
= 0°C to +85°C, typical values are at TA= +25°C,
unless otherwise noted.)
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
ELECTRICAL CHARACTERISTICS (continued)(VV+= VVL= VAVL= VEN= VREFIN= 5V, VBST= 6V, VLX= 1V, CVL= 4.7µF, CREFOUT= 1µF, VAIN-= VAOUT, VAIN+= 2.5V, VILIM=
VLX- 0.2V, VFB= 0.65V, GND = PGND = 0V, CSS= 0.01µF, RFREQ= 20kΩ, TA
= 0°C to +85°C, typical values are at TA= +25°C,
unless otherwise noted.)
ELECTRICAL CHARACTERISTICS(VV+= VVL= VAVL= VEN= VREFIN= 5V, VBST= 6V, VLX= 1V, CVL= 4.7µF, CREFOUT= 1µF, VAIN-= VAOUT, VAIN+= 2.5V, VILIM=
VLX- 0.2V, VFB= 0.65V, GND = PGND = 0V, CSS= 0.01µF, RFREQ= 20kΩ, TA
= -40°C to +85°C, typical values are at TA= +25°C,
unless otherwise noted.) (Note 1)
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
ELECTRICAL CHARACTERISTICS (continued)(VV+= VVL= VAVL= VEN= VREFIN= 5V, VBST= 6V, VLX= 1V, CVL= 4.7µF, CREFOUT= 1µF, VAIN-= VAOUT, VAIN+= 2.5V, VILIM=
VLX- 0.2V, VFB= 0.65V, GND = PGND = 0V, CSS= 0.01µF, RFREQ= 20kΩ, TA
= -40°C to +85°C, typical values are at TA= +25°C,
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
ELECTRICAL CHARACTERISTICS (continued)(VV+= VVL= VAVL= VEN= VREFIN= 5V, VBST= 6V, VLX= 1V, CVL= 4.7µF, CREFOUT= 1µF, VAIN-= VAOUT, VAIN+= 2.5V, VILIM=
VLX- 0.2V, VFB= 0.65V, GND = PGND = 0V, CSS= 0.01µF, RFREQ= 20kΩ, TA
= -40°C to +85°C, typical values are at TA= +25°C,
unless otherwise noted.) (Note 1)
EFFICIENCY vs. LOAD CURRENT
CIRCUIT OF FIGURE 1MAX8597 toc01
LOAD CURRENT (A)
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT
CIRCUIT OF FIGURE 2
MAX8597 toc02
LOAD CURRENT (A)
EFFICIENCY (%)
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX8597 toc03
ILOAD (A)
OUTPUT VOLTAGE (V)161412108642
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
MAX8597 toc04
VIN (V)
OUTPUT VOLTAGE (V)
POWER-UP WAVEFORMS
MAX8597 toc05
2ms/div
5V/divVAVL
ILX
VOUT
VIN
10A/div
1V/div
10V/div
POWER-DOWN WAVEFORMSMAX8597 toc06
2ms/div
5V/divVAVL
ILX
IOUT
VIN
10A/div
1V/div
10V/div
Typical Operating Characteristics(Circuit of Figure 4, TA= +25°C, 500kHz switching frequency, VIN= 12V, unless otherwise noted.)
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
OUTPUT PREBIASED STARTUPMAX8597 toc07
1ms/div
10V/divVLX
VOUT
VIN
VDL
1.0V
1.2V
5V/div
5V/div
STARTUP/SHUTDOWN WITH
EN (ILOAD = 20A)MAX8597 toc08
2ms/div
5V/divVPOK
ILX
VOUT
VEN
10A/div
1V/div
5V/div
OUTPUT VOLTAGE vs. VADJ
(VIN = 12V)MAX8597 toc09
VADJ (V)
OUTPUT VOLTAGE (V)4321
ENTERING DROPOUT WAVEFORMS
CIRCUIT OF FIGURE 1MAX8597 toc10
2µs/div
10V/divVLX
VOUT
VCOMP
VIN
(AC-COUPLED)
11V
500mV/div
100mV/div
HEAVY-DROPOUT WAVEFORMS
CIRCUIT OF FIGURE 1MAX8597 toc11
10µs/div
10V/divVLX
VOUT
VCOMP
VIN
(AC-COUPLED)
11.9V
500mV/div
500mV/div
OUTPUT TRACKING REFINMAX8597 toc12
1ms/div
VREFIN
VOUT
1V/div
VREFIN
VOUT
1V/div
ypical Operating Characteristics (continued)(Circuit of Figure 4, TA= +25°C, 500kHz switching frequency, VIN= 12V, unless otherwise noted.)
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
Typical Operating Characteristics (continued)(Circuit of Figure 4, TA= +25°C, 500kHz switching frequency, VIN= 12V, unless otherwise noted.)
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
Block Diagram
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
Pin Description
MAX8597/MAX8598/MAX8599
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
Pin Description (continued)
Detailed DescriptionThe MAX8597/MAX8598/MAX8599 voltage-mode PWM
step-down controllers are designed to operate from
4.5V to 28V input and generate output voltages down to
0.6V. A proprietary switching algorithm stretches the
duty cycle to >99.5% for low-dropout design. Unlike
conventional step-down regulators using a p-channel
high-side MOSFET to achieve high duty cycle, the
MAX8597/MAX8598/MAX8599 drive n-channel
MOSFETs permitting high efficiency and high-current
designs.
The MAX8597 is available in a 20-pin thin QFN pack-
age and is designed for applications that use an ana-
log signal to control the output voltage with adjustable
offset, such as DC fan speed control. For example, a
12VDC fan can be driven from 6V to 12V with 12V input
power source depending on the system’s cooling
requirement to minimize fan noise and power consump-
tion. This is achieved with an internal uncommitted
operational amplifier. With the addition of an external
RC filter, a PWM input can also be used to control the
output voltage. The MAX8597 also generates a tracking
output for chipsets, ASICs, and DSP where core and
I/O supplies are split and require tracking. In applica-
tions where tighter output tolerance is required, the
MAX8597 output can be set by an external precision
reference source feeding to REFIN. The MAX8598/
MAX8599 are available in a 16-pin thin QFN package
and do not have the uncommitted operational amplifier,
reference input, and reference output, but offer a power-
OK output (POK). With the enable input and POK out-
put, the MAX8598/MAX8599 can easily be configured to
have power sequencing of multiple supply rails.
The MAX8597/MAX8598/MAX8599 allow startup with
prebias voltage on the output for applications where a
backup supply or a tracking device may charge the
output capacitor before the MAX8597/MAX8598/
MAX8599 are enabled. The MAX8599 has output over-
voltage protection.
These controllers feature lossless high-side peak
inductor current sensing, adjustable current limit, and
hiccup-mode short-circuit protection. Switching fre-
quency is set with an external resistor from 200kHz to
1.4MHz. This wide frequency range combined with a
wide-bandwidth error amplifier enable the loop-com-
pensation scheme to give the user ample flexibility to
optimize for cost, size, and efficiency.
DC-DC ControllerThe MAX8597/MAX8598/MAX8599 step-down DC-DC
controllers use a PWM voltage-mode control scheme. An
internal high-bandwidth (25MHz) operational amplifier is
used as an error amplifier to regulate the output voltage.
The output voltage is sensed and compared with an inter-
nal 0.6V reference or REFIN (MAX8597) to generate an
error signal. The error signal is then compared with a
fixed-frequency ramp by a PWM comparator to give the
appropriate duty cycle to maintain output voltage regula-
tion. The high-side MOSFET turns on at the rising edge of
the internal clock 20ns after DL (the low-side MOSFET
gate drive) goes low. The high-side MOSFET turns off
once the internal ramp voltage reaches the error-amplifier
output voltage. The process repeats for every clock
cycle. During the high-side MOSFET on-time, current
flows from the input through the inductor to the output
capacitor and load. At the moment the high-side MOS-
FET turns off, the energy stored in the inductor during the
on-time is released to support the load as the inductor
MAX8597/MAX8598/MAX8599current ramps down through the low-side MOSFET body
diode; 20ns after DH goes low, the low-side MOSFET
turns on, resulting in a lower voltage drop to increase effi-
ciency. The low-side MOSFET turns off at the rising edge
of the next clock pulse, and when its gate voltage dis-
charges to zero, the high-side MOSFET turns on and
another cycle starts.
These controllers also sense peak inductor current and
provide hiccup-overload and short-circuit protection
(see the Current Limit section). The MAX8597/
MAX8598/MAX8599 operate in forced-PWM mode
where the inductor current is always continuous. The
controller maintains constant switching frequency
under all loads, except under dropout conditions where
it skips DL pulses.
Current LimitThe MAX8597/MAX8598/MAX8599 DC-DC step-down
controllers sense the peak inductor current either with
the on-resistance of the high-side MOSFET for lossless
sensing, or a series resistor for more accurate sensing.
When the voltage across the sensing element exceeds
the current-limit threshold set with ILIM, the controller
immediately turns off the high-side MOSFET. The low-
side MOSFET is then turned on to let the inductor cur-
rent ramp down. As the output load current increases
above the ILIM threshold, the output voltage sags
because the truncated duty cycle is insufficient to sup-
port the load current. When FB falls 30% below its nomi-
nal threshold, the output undervoltage protection is
triggered and the controller enters hiccup mode to limit
power dissipation. This current-limit method allows the
circuit to withstand a continuous output short circuit.
The MAX8597/MAX8598/MAX8599 current-limit thresh-
old is set by an external resistor that works in conjunc-
tion with an internal 200µA current sink (see the Setting
the Current Limit section for more details).
Synchronous-Rectifier Driver (DL)Synchronous rectification reduces the conduction loss
in the rectifier by replacing the normal Schottky catch
diode with a low-resistance MOSFET switch. The
MAX8597/MAX8598/MAX8599 also use the synchro-
nous rectifier to ensure proper startup of the boost
gate-drive circuit.
High-Side Gate-Drive Supply (BST)Gate-drive voltage for the high-side n-channel MOSFET is
generated by an external flying capacitor and diode boost
circuit (D1 and C5 in Figure 1). When the synchronous
rectifier is on, C5 is charged from the VL supply through
the Schottky diode. When the synchronous rectifier is
turned off, the Schottky is reverse biased and the voltage
on C5 is stacked above LX to provide the necessary turn-
on voltage for the high-side MOSFET. A low-current
Schottky diode, such as Central Semiconductor’s
CMDSH-3, works well for most applications. The capacitor
should be large enough to prevent it from charging to
excessive voltage, but small enough to adequately charge
during the minimum low-side MOSFET on-time, which
occurs at minimum input voltage. A capacitor in the 0.1µF
to 0.47µF range works well for most applications.
Internal 5V Linear RegulatorThe MAX8597/MAX8598/MAX8599 contain a low-
dropout 5V regulator that provides up to 35mA to sup-
ply gate drive for the external MOSFETs, and supplies
AVL, which powers the IC’s internal circuitry. Bypass
the regulator’s output (VL) with 1µF per 10mA of VL
load, or greater ceramic capacitor. The current
required to drive the external MOSFET can be estimat-
ed by multiplying the total gate charge (at VGS= 5V) of
the MOSFETs by the switching frequency.
Undervoltage Lockout (UVLO)When VVLdrops below 3.75V (typ), the MAX8597/
MAX8598/MAX8599s’ undervoltage-lockout (UVLO) cir-
cuitry inhibits switching, forces POK (MAX8598/
MAX8599) low, and forces DH and DL low. Once VVL
rises above 4.2V (typ), the controller powers up the out-
put in startup mode (see the Startupsection).
StartupThe MAX8597/MAX8598/MAX8599 start switching once
all the following conditions are met:EN is high.VVL> 4.2V (typ).Soft-start voltage VSSexceeds VFB.Thermal limit is not exceeded.
The third condition ensures that the MAX8597/
MAX8598/MAX8599 do not discharge a prebiased out-
put. Once all of these conditions are met, the IC begins
switching and the soft-start cycle is initiated.
Low-Dropout, Wide-Input-Voltage,
Step-Down Controllers
