Analog Devices Inc./Maxim Integrated

The MAX1534 is a high-efficiency, triple-output power supply for keep-alive (always on) voltage rails. The 500mA buck regulator with an internal current-limited 0.5Ω PMOS steps down the battery or wall adapter supply rail to a fixed 5V or an adjustable output voltage. Two integrated low-voltage linear regulators follow this output and provide two independent preset output voltages of 3.3V and 1.8V, or adjustable output voltages.The buck regulator utilizes a peak current-limit, pulse-frequency modulation (PFM) architecture for highest light-load efficiency to conserve battery life. High switching frequencies (up to 200kHz) allow the use of tiny surface-mount inductors and output capacitors. Operation to 100% duty cycle minimizes dropout voltage (250mV at 500mA).The low-dropout linear regulators use an internal P-channel metal-oxide (PMOS) pass transistor to minimize supply current and deliver up to 160mA each of continuous current.The MAX1534 includes a power-OK (POK) signal that indicates all outputs are in regulation. The 4% accurate threshold of the active-low SHDN input permits its use as a low-battery detector.The MAX1534 is available in a small 16-pin thin QFN (4mm x 4mm) package, occupying 33% less board space than discrete solutions.Applications2 to 4 Li+ Cell Battery-Powered DevicesHandheld DevicesKeep-Alive SuppliesNotebook and Subnotebook ComputersStandby SuppliesWake On LAN®

The MAX1536 constant-off-time, pulse-width-modulated (PWM) step-down DC-to-DC converter is ideal for use in +5.0V and +3.3V to low voltages for notebook and subnotebook computers. The MAX1536 features an internal PMOS power switch and internal synchronous rectification for high efficiency and reduced component count. No external Schottky diode is required across the internal synchronous rectifier switch. The internal 54mΩ PMOS power switch and 47mΩ NMOS synchronous-rectifier switch easily deliver continuous load currents up to 3.6A. The MAX1536 produces dynamically adjustable output voltages for chipsets and graphics processor cores using a logic-level control signal. The MAX1536 achieves efficiencies as high as 96%.The MAX1536 uses a unique current-mode, constant-off-time, PWM control scheme. It has selectable Idle Mode™ to maintain high efficiency during light-load operation, or fixed-PWM mode for low output ripple. The programmable constant-off-time architecture allows a wide range of switching frequencies up to 1.4MHz, optimizing performance trade-offs between efficiency, output switching noise, component size, and cost. The MAX1536 features a digital soft-start to limit surge currents during startup, a 100% duty-cycle mode for low-dropout operation, and a low-power shutdown mode that disconnects the input from the output and reduces supply current below 1µA. The MAX1536 is available in a 28-pin thin QFN package with an exposed backside pad.ApplicationsActive Termination BusesChipset/Graphics Cores with Dual-Supply VoltagesDDR Memory TerminationNotebook Computers

The MAX1538 selector provides power-source control for dual-battery systems. The device selects between an AC adapter and dual batteries based on the presence of the three power sources and the state of charge of each battery. The MAX1538 includes analog comparators to detect AC/airline-adapter presence and determine battery undervoltage. Fast analog circuitry allows the device to switch between power sources to implement a break-before-make time, which allows hot swapping of battery packs. The MAX1538 independently performs power-source monitoring and selection, freeing the system power-management µP for other tasks. This simplifies the development of µP power-management firmware and allows the µP to enter standby, reducing system power consumption.The MAX1538 supports "relearn mode," which allows the system to measure and fully utilize battery capacity. In this state, the part allows the selected battery to be discharged even when an AC adapter is present. The MAX1538 can also be used to power the system in an aircraft. On detecting an airline adapter, the MAX1538 automatically disables charging or discharging of battery packs and only allows the system to be powered from the adapter.The MAX1538 is available in a space-saving 28-pin thin QFN package with a maximum footprint of 5mm x 5mm.ApplicationsDual-Battery Portable EquipmentInternet TabletsNotebook and Subnotebook Computers

The MAX154/MAX158 are high-speed multi-channel analog-to-digital converters (ADCs). The MAX154 has four analog input channels while the MAX158 has eight channels. Conversion time for both devices is 2.5µs. The MAX154/MAX158 also feature a 2.5V on-chip reference, forming a complete high-speed data acquisition system.Both converters include a built-in track/hold, eliminating the need for an external track/hold. The analog input range is 0V to +5V, although the ADC operates from a single +5V supply.Microprocessor interfaces are simplified by the ADC's ability to appear as a memory location or I/O port without the need for external logic. The data outputs use latched, three-state buffer circuitry to allow direct connection to a microprocessor data bus or system input port.ApplicationsAudio InstrumentationDigital Signal Processing (DSP)High-Speed Data AcquisitionHigh-Speed Servo ControlTelecommunications