MAX1623EAP ,3A / Low-Voltage / Step-Down Regulator with Synchronous Rectification and Internal Switchesfeatures constant-off-time, current-mode ♦ Minimal External Componentspulse-width-modulation (PWM) ..
MAX1623EAP/T ,3A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal SwitchesApplications♦ Idle Mode™ Operation at Light Loads5V to 3.3V Conversion♦ Thermal Shutdown Protection ..
MAX1623EAP+ ,3A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal SwitchesELECTRICAL CHARACTERISTICS(V = V = 5V, FBSEL unconnected, R = 110kΩ, T = 0°C to +85°C, unless other ..
MAX1623EAP+ ,3A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal SwitchesApplications that forward bias these diodes should take care not to exceedthe IC’s package power di ..
MAX1623EAP+T ,3A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal SwitchesGeneral Description ________
MAX1623EAP+T ,3A, Low-Voltage, Step-Down Regulator with Synchronous Rectification and Internal Switchesfeatures constant-off-time, current-mode ♦ Minimal External Componentspulse-width-modulation (PWM) ..
MAX4360EAX ,Low-Cost 4x4 / 8x4 / 8x8 Video Crosspoint SwitchesApplicationsMAX4456EPL -40°C to +85°C 40 Plastic DIPHigh-Speed Signal Video Test EquipmentMAX4456EQ ..
MAX4360EAX ,Low-Cost 4x4 / 8x4 / 8x8 Video Crosspoint Switchesapplications requiring Serial or Parallel Digital Interfaceincreased drive capability, buffer the ..
MAX4360EAX+ ,Low-Cost 4x4, 8x4, 8x8 Video Crosspoint SwitchesMAX4359/MAX4360/MAX445619-1389; Rev 2; 2/07Low-Cost 4x4, 8x4, 8x8Video Crosspoint Switches
MAX4360EAX+ ,Low-Cost 4x4, 8x4, 8x8 Video Crosspoint Switchesapplications requiringP-P♦ Expandable for Larger Switch Matricesincreased drive capability, buffer ..
MAX4360EAX+T ,Low-Cost 4x4, 8x4, 8x8 Video Crosspoint SwitchesApplications40 Plastic DIPMAX4456EPL -40°C to +85°C P40-1High-Speed Signal Video Test Equipment44 P ..
MAX4364ESA ,1.4W and 1W / Ultra-Small / Audio Power Amplifiers with ShutdownELECTRICAL CHARACTERISTICS—5V(V = 5V, R = ∞, C = 1µF to GND, SHDN = GND, T = +25°C, unless otherwis ..
MAX1623EAP
3A / Low-Voltage / Step-Down Regulator with Synchronous Rectification and Internal Switches
MAX1623
3A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
General DescriptionThe MAX1623 switch-mode buck regulator with syn-
chronous rectification provides local CPU and bus-ter-
mination power in notebook and desktop computers.
An internal 55mW(typ), 3A PMOS power switch and
60mW (typ), 3A NMOS synchronous-rectifier switch
deliver continuous load currents up to 3A from a 5V
supply with 95% typical efficiency. Output accuracy is
±1%, including line and load regulation.
The MAX1623 features constant-off-time, current-mode
pulse-width-modulation (PWM) control with switching
frequencies as high as 350kHz. An external resistor at
the TOFF pin sets the off-time, allowing optimum design
flexibility in terms of switching frequency, output switch-
ing noise, and inductor size. This device is available in
a space-saving 20-pin SSOP package.
________________________Applications5V to 3.3V Conversion
Notebook Computer CPU I/O Supply
Desktop Computer Bus-Termination Supply
CPU Daughter Card Supply
DSP Supply
____________________________Features±1% Output Accuracy, Including Line and Load
Regulation94% EfficiencyInternal Switches
55mΩPMOS Power Switch
60mΩNMOS Synchronous-Rectifier SwitchGuaranteed 3A Load CapabilityMinimal External ComponentsPin-Selectable Fixed 3.3V, 2.5V, or
Adjustable (1.1V to 3.8V) Output Voltage+4.5V to +5.5V Input Voltage Range400μA (typ) Supply Current <1μA Shutdown Supply CurrentConstant-Off-Time PWM OperationSwitching Frequencies Up to 350kHzIdle Mode™Operation at Light LoadsThermal Shutdown ProtectionAvailable in 20-Pin SSOP
Pin Configuration
Typical Operating CircuitIdle Mode is a trademark of Maxim Integrated Products.
MAX1623
3A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VIN= VCC= +5V, FBSEL unconnected, RTOFF= 110kΩ, 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.
IN to PGND.....................................................................0V to 6V
VCCto GND................................................................-0.3V to 6V
PGND to GND.....................................................................±0.5V
IN to VCC.............................................................................±0.5V
LX to PGND.................................................................-0.5V to 6VSHDNto GND.............................................................-0.3V to 6V
REF, FBSEL, COMP, FB, TOFF to GND.....-0.3V to (VCC+ 0.3V)
REF Short to GND......................................................Continuous
Continuous Power Dissipation (TA= +70°C) (with part mounted
on 1 sq. inch of one ounce copper)
20-Pin SSOP (derate 22mW/°C above +70°C)................1.3W
Operating Temperature Range...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10sec).............................+300°C
MAX1623
3A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
ELECTRICAL CHARACTERISTICS(VIN= VCC= +5V, FBSEL unconnected, RTOFF= 110kΩ, TA
= -40°C to +85°C, unless otherwise noted.) (Note 3)
Note 1:Guaranteed by design, not production tested.
Note 2:Idle Mode threshold is defined as the transition point in the load-current range between Idle Mode and constant-off-time
operation.
Note 3:Specifications to -40°C are guaranteed by design, not production tested.
MAX1623
3A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
__________________________________________Typical Operating Characteristics(Circuit of Figure 2, TA = +25°C, unless otherwise noted.)
MAX1623
3A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
____________________________Typical Operating Characteristics(continued)(Circuit of Figure 2, TA = +25°C, unless otherwise noted.)
MAX1623
3A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
General DescriptionThe MAX1623 current-mode, PWM, DC-DC regulator is
designed for 5V-input step-down applications. It fea-
tures a 55mΩ(typ) PMOS switch and a 60mΩ(typ)
NMOS synchronous-rectifier switch. Simple constant-off-
time control allows switching frequencies up to 350kHz.
Adjust the off-time with an external resistor RTOFF to
optimize performance trade-offs among efficiency, com-
ponent size, output switching noise, and cost. Idle Mode
operation enhances light-load efficiency by switching to
a pulse-skipping mode that reduces transition and gate-
charge losses. The power-switching circuit consists of
the IC and an LC output filter. The output voltage is the
average of the AC voltage at the switching node (LX).
The MAX1623 regulates the output voltage by changing
the PMOS switch on-time relative to the constant off-
time, thereby adjusting the duty cycle.
The MAX1623 contains six major circuit blocks (Figure 1):
a PWM comparator, a current-sense circuit, a PWM
logic block, an internal feedback mux, an off-time con-
trol block, and a 1.1V precision reference. The input
supply directly powers the internal blocks.
Modes of OperationThe load current determines the mode of operation:
Idle Mode (load currents less than 0.625A) or PWM
mode for inductor currents of 1.25A (which corre-
sponds to load currents greater than 0.625A). The
PWM current limit is continuously adjusted by the PWM
comparator and can vary from 0A to the maximum cur-
rent limit (4A). If the inductor current falls below the Idle
Mode threshold (1.25A), skip mode takes over.
Whenever the P-channel switch turns on, it stays on
until the sensed current reaches the active current limit.
The PWM current limit automatically adjusts with the
PMOS switch duty cycle required to generate the
desired output voltage. When the active current limit is
met, the PMOS switch turns off for the programmed
minimum off-time, and the N-channel synchronous rec-
tifier turns on. The synchronous rectifier stays on until
the P-channel switch turns back on or until the inductor
current reaches zero. At the end of the off-time, the P-
channel switch turns on again if the output voltage indi-
cates that energy is required at the output.
Pin Description
