MAX1637EEE ,Miniature / Low-Voltage / Precision Step-Down ControllerELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = V = 5V, SYNC = V , I = 0mA, T = 0°C to +85°C, u ..
MAX1637EEE+ ,Miniature, Low-Voltage, Precision Step-Down Controllerfeatures a logic-controlled and synchro-MAX1637EEE 40°C to +85°C 16 QSOPnizable, fixed-frequency, p ..
MAX1637EEE+T ,Miniature, Low-Voltage, Precision Step-Down ControllerELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, V = V = 5V, SYNC = V , I = 0mA, T = 0°C ..
MAX1638EAG ,High-Speed Step-Down Controller with Synchronous Rectification for CPU PowerApplicationsPentium Pro™, Pentium II™, PowerPC™, Alpha™,TO VDD MAX1638DHand K6™ SystemsWorkstations ..
MAX1638EAG ,High-Speed Step-Down Controller with Synchronous Rectification for CPU Powerapplications in which' Greater than 90% Efficiency Using N-Channeloutput voltage precision and good ..
MAX1638EAG+ ,High-Speed Step-Down Controller with Synchronous Rectification for CPU PowerELECTRICAL CHARACTERISTICS(V = V = D4 = +5V, PGND = AGND = D0–D3 = 0V, FREQ = REF, T = 0°C to +85°C ..
MAX4382EUD ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and DisableELECTRICAL CHARACTERISTICS–Single Supply (V = +5V, V = 0, V = V /2, V = V /2, R = ∞ to V /2, DISABL ..
MAX4382EUD+T ,Ultra-Small, Low-Cost, 210MHz, Single-Supply Op Amps with Rail-to-Rail Outputs and DisableApplicationsOrdering InformationSet-Top BoxesPIN- TOPSurveillance Video SystemsPART TEMP RANGEPACKA ..
MAX4383EEE ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and Disableapplications). Single +4.5V to +11V OperationThe MAX4380–MAX4384 require only 5.5mA of quies- Rai ..
MAX4383ESD ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and DisableApplicationsOrdering InformationSet-Top BoxesPIN- TOPSurveillance Video SystemsPART TEMP RANGEPACKA ..
MAX4383ESD ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and Disableapplications). Single +4.5V to +11V OperationThe MAX4380–MAX4384 require only 5.5mA of quies- Rai ..
MAX4383ESD ,Ultra-Small / Low-Cost / 210MHz / Single-Supply Op Amps with Rail-to-Rail Outputs and DisableApplicationsOrdering InformationSet-Top BoxesPIN- TOPSurveillance Video SystemsPART TEMP RANGEPACKA ..
MAX1637EEE
Miniature / Low-Voltage / Precision Step-Down Controller
General DescriptionThe MAX1637 synchronous, buck, switch-mode power-
supply controller generates the CPU supply voltage in
battery-powered systems. The MAX1637 is a stripped-
down version of the MAX1636 in a smaller 16-pin QSOP
package. The MAX1637 is intended to be powered sep-
arately from the battery by an external bias supply (typi-
cally the +5V system supply) in applications where the
battery exceeds 5.5V. The MAX1637 achieves excellent
DC and AC output voltage accuracy. This device can
operate from a low input voltage (3.15V) and delivers the
excellent load-transient response needed by upcoming
generations of dynamic-clock CPUs.
Using synchronous rectification, the MAX1637 achieves
up to 95% efficiency. Efficiency is greater than 80%
over a 1000:1 load-current range, which extends bat-
tery life in system-suspend or standby mode. Excellent
dynamic response corrects output load transients
caused by the latest dynamic-clock CPUs within five
300kHz clock cycles. Powerful 1A on-board gate driv-
ersensure fast external N-channel MOSFET switching.
The MAX1637 features a logic-controlled and synchro-
nizable, fixed-frequency, pulse-width-modulation
(PWM) operating mode. This reduces noise and RF
interference in sensitive mobile-communications and
pen-entry applications. Asserting the SKIPpin enables
fixed-frequency mode, for lowest noise under all load
conditions. For a stand-alone device that includes a
+5V VL linear regulator and low-dropout capabilities,
refer to the MAX1636 data sheet.
________________________ApplicationsNotebook ComputersSubnotebook Computers
Handy-Terminals, PDAs
____________________________Features±2% DC Accuracy0.1% (typ) DC Load Regulation Adjustable Switching Frequency to 350kHzIdle Mode™Pulse-Skipping Operation1.10V to 5.5V Adjustable Output Voltage3.15V Minimum IC Supply Voltage (at VCCpin)Internal Digital Soft-Start1.1V ±2% Reference Output1µA Total Shutdown Current Output Overvoltage Crowbar ProtectionOutput Undervoltage Shutdown (foldback)Tiny 16-Pin QSOP Package
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
__________________Pin Configuration
__________Typical Operating CircuitIdle Mode is a trademark of Maxim Integrated Products.
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, VCC= VGG= 5V, SYNC = VCC, IREF= 0mA, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at = +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.
GND to PGND.............................................................+2V to -2V
LX, BST to GND......................................................-0.3V to +36V
BST, DH to LX...........................................................-0.3V to +6V
VCC, VGG, CSL, CSH, SHDNto GND.......................-0.3V to +6V
DL to GND..................................................-0.3V to (VGG+ 0.3V)
REF, SKIP, SYNC, CC to GND...................-0.3V to (VCC+ 0.3V)
REF Output Current.............................................................20mA
REF Short-Circuit to GND..............................................Indefinite
Operating Temperature Range...........................-40°C to +85°C
Continuous Power Dissipation (TA= +70°C)
QSOP (derate 8.3mW/°C above +70°C)......................667mW
Storage Temperature Range.............................-65°C to +160°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10sec).............................+300°C
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VCC= VGG= 5V, SYNC = VCC, IREF= 0mA, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at = +25°C.)
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, VCC= VGG= 5V, SYNC = VCC, IREF= 0mA, TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, VCC= VGG= 5V, SYNC = VCC, IREF= 0mA, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
Note 1:Guaranteed by design, not production tested.
Note 2:Specifications from -40°C to 0°C are guaranteed by design and not production tested.
__________________________________________Typical Operating Characteristics
(VOUT= 3.3V, TA = +25°C, unless otherwise noted.)
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
____________________________________Typical Operating Characteristics (continued)
(VOUT= 3.3V, TA = +25°C, unless otherwise noted.)
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
____________________________________Typical Operating Characteristics (continued)
(VOUT= 3.3V, TA = +25°C, unless otherwise noted.)
______________________________________________________________Pin Description
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
Figure 1. Standard Application Circuit
______Standard Application Circuit
The basic MAX1637 buck converter (Figure 1) is easily
adapted to meet a wide range of applications where a
5V or lower supply is available. The components listed
in Table 1 represent a good set of trade-offs among
cost, size, and efficiency, while staying within the worst-
case specification limits for stress-related parameters
such as capacitor ripple current. Do not change the cir-
cuit’s switching frequency without first recalculating
component values (particularly inductance value at
maximum battery voltage).
The power Schottky diode across the synchronous rec-
tifier is optional because the MOSFETs chosen incorpo-
rate a high-speed silicon diode. However, installing the
Schottky will generally improve efficiency by about 1%.
If used, the Schottky diode DC current must be rated to
at least one-third of the maximum load current.
_______________Detailed Description
The MAX1637 is a BiCMOS, switch-mode power-supply
(SMPS) controller designed primarily for buck-topology
regulators in battery-powered applications where high
efficiency and low quiescent supply current are critical.
Light-load efficiency is enhanced by automatic idle-
mode operation—a variable-frequency, pulse-skipping
mode that reduces transition and gate-charge losses.
The step-down, power-switching circuit consists of two
N-channel MOSFETs, a rectifier, and an LC output filter.
Output voltage for this device is the average AC volt-
age at the switching node, which is regulated by
changing the duty cycle of the MOSFET switches. The
gate-drive signal to the high-side N-channel MOSFET,
which must exceed the battery voltage, is provided by
a flying-capacitor boost circuit that uses a 100nF
capacitor between BST and LX. Figure 2 shows the
major circuit blocks.
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
Table 1. Component Selection for Standard Applications
Table 2. Component Suppliers
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
The pulse-width-modulation (PWM) controller consists
of a multi-input PWM comparator, high-side and low-
side gate drivers, and logic. It uses a 200kHz/300kHz
synchronizable oscillator. The MAX1637 contains fault-
protection circuits that monitor the PWM output for
undervoltage and overvoltage. It includes a 1.100V pre-
cision reference. The circuit blocks are powered from
an internal IC power rail that receives power from VCC.
VGGprovides direct power to the synchronous-switch
gate driver, but provides indirect power to the high-
side-switch gate driver via an external diode-capacitor
boost circuit.
Figure 2. Functional Diagram
MAX1637
Miniature, Low-Voltage,
Precision Step-Down Controller
PWM Controller Block
The heart of the current-mode PWM controller is a
multi-input, open-loop comparator that sums four sig-
nals: the output voltage error signal with respect to
the reference voltage, the current-sense signal, the
integrated voltage-feedback signal, and the slope-
compensation ramp (Figure 3). The PWM controller is
a direct-summing type, lacking a traditional error
amplifier and the phase shift associated with it. This
direct-summing configuration approaches ideal
cycle-by-cycle control over the output voltage.
Figure 3. PWM Controller Functional Diagram
