Analog Devices Inc./Maxim Integrated

The MAX1672 integrates a step-up DC-DC converter with a linear regulator to provide step-up/down voltage conversion. This device provides a constant output voltage for inputs that vary above and below the output voltage. It has a 1.8V to 11V input range and a preset 3.3V or 5V output. The output can also be set from 1.25V to 5.5V using two resistors. Typical efficiency is 85%.The MAX1672's step-up/linear-regulator configuration permits the use of a single, physically smaller inductor than can be used with competing SEPIC and flyback configurations. Switch current is also selectable, permitting the use of smaller inductors in low-current applications. The linear regulator also acts as a filter to reduce output ripple voltage.The MAX1672 has a low 85µA quiescent supply current, which is further reduced to 0.1µA in logic-controlled shutdown. The output voltage is disconnected from the input in shutdown. The MAX1672 also has a PGI/PGO-bar low-battery detector.The MAX1672 comes in a 16-pin QSOP package (same size as a standard 8-pin SO). For a larger device that delivers more output current, refer to the MAX710/MAX711. The preassembled MAX1672 evaluation kit is available to speed designs.Applications2-Cell to 4-Cell AA Alkaline Handheld Equipment3.3V and Other Low-Voltage SystemsBattery-Powered DevicesDigital CamerasSingle-Cell, Lithium-Powered Portable Devices with AC Input Adapters

The MAX16731 is a fully integrated, highly efficient, step-down DC-DC switching regulator. The regulator is able to operate from 2.7V to 16V input supplies, and the output can be adjusted from 0.5V to 5.8V, delivering up to 30A of load current.The switching frequency of the device can be configured from 500kHz to 1.5MHz and can optimize the design in terms of size and performance.The MAX16731 utilizes fixed frequency, current-mode control with internal compensation. The IC features advanced modulation scheme (AMS) and selectable discontinuous current mode (DCM) operation to provide improved performance. Operation settings and configurable features can be selected by three programming pins PGM0, PGM1, and PGM2.The MAX16731 has an internal 1.8V linear regulator (LDO) output to power the gate drives (VCC) and internal circuitry (AVDD).The IC has multiple protections, including positive and negative overcurrent protection, output overvoltage protection, and overtemperature protection to ensure robust design.The device is available in a compact 2.52mm x 4.89mm WLP package. It supports -40°C to +125°C junction temperature operation.ApplicationsCommunications EquipmentMemory VDDQNetworking EquipmentPoint-of-Load Voltage RegulatorsServers and Storage Equipment

The MAX1674/MAX1675/MAX1676 compact, high-efficiency, step-up DC-DC converters fit in small µMAX packages. They feature a built-in synchronous rectifier, which improves efficiency and reduces size and cost by eliminating the need for an external Schottky diode. Quiescent supply current is only 16µA.The input voltage ranges from 0.7V to VOUT, where VOUTcan be set from 2V to 5.5V. Start-up is guaranteed from 1.1V inputs. The MAX1674/MAX1675/MAX1676 have a preset, pin-selectable output for 5V or 3.3V. The outputs can also be adjusted to other voltages using two external resistors.All three devices have a 0.3Ω N-channel MOSFET power switch. The MAX1674 has a 1A current limit. The MAX1675 has a 0.5A current limit, which permits the use of a smaller inductor. The MAX1676 comes in a 10-pin µMAX package and features an adjustable current limit and circuitry to reduce inductor ringing.Applications1- to 3-Cell Handheld DevicesHandheld ComputersMedical DevicesPagersPDAsRF TagsWireless Phones

The MAX1677 is a compact, high-efficiency, dual-output boost converter for portable devices needing two regulated supplies, typically for logic and liquid crystal displays (LCDs). Operation with inputs as low as 0.7V allows the MAX1677 to accept 1, 2, or 3-cell alkaline, NiCd, or NiMH batteries as well as 1-cell lithium-ion batteries. The device requires no external FETs and can maintain regulation while consuming only 20µA, making it ideal for hand-held pen-input and PDA devices operating with low-current "sleep" states.The MAX1677's primary regulator supplies up to 350mA at either a factory-preset 3.3V or an adjustable 2.5V to 5.5V output. On-chip synchronous rectification provides efficiencies up to 95%. 300kHz (or externally clocked) pulse-width-modulation (PWM) operation is particularly suitable for applications needing low noise, such as those with wireless features. The primary converter also features pin-selectable pulse-frequency-modulation (PFM) operation that consumes only 20µA. A 1µA shutdown state also minimizes battery drain.The MAX1677's secondary step-up converter supplies up to +28V or -28V for LCD bias, varactor tuning, or other high-voltage, low-current functions. Other MAX1677 features include precision reference, logic control inputs for both regulators, and an uncommitted comparator for low-battery detection or a reset function. The MAX1677 is supplied in Maxim's compact 16-pin QSOP package, which occupies no more space than a standard SO-8.ApplicationsHandheld TerminalsPDAsPortable InstrumentationPortable Phones

The MAX1678 is a high-efficiency, low-voltage, synchronous-rectified, step-up DC-DC converter intended for use in devices powered by 1 to 3-cell alkaline, NiMH, or NiCd batteries or a 1-cell lithium battery. It guarantees a 0.87V start-up voltage and features a low 37µA quiescent supply current.The device includes a 1Ω, N-channel MOSFET power switch, a synchronous rectifier that acts as the catch diode, a reference, pulse-frequency-modulation (PFM) control circuitry, and circuitry to reduce inductor ringing-all in an ultra-small, 1.1mm-high µMAX® package.The output voltage is preset to 3.3V or can be adjusted from +2V to +5.5V using only two resistors. Efficiencies up to 90% are achieved for loads up to 50mA. The device also features an independent undervoltage comparator (PFI/PFO) and a logic-controlled 2µA shutdown mode.ApplicationsPagersPersonal Medical MonitorsPointing DevicesRemote ControlsSingle-Cell Battery-Powered Devices