Analog Devices

The LTC2926 provides a simple solution for tracking and sequencing up to three power supply rails. An N-channel MOSFET and a few resistors per channel configure the load voltages to ramp up and down together, with voltage offsets, with time delays or with different ramp rates.Automatic remote sense switching compensates for voltage drops across the MOSFETs. The LTC2926 provides two integrated switches as well as a signal to control optional additional external N-channel MOSFET sense switches.The LTC2926 includes I/O signals for communication with other devices. The status output asserts after tracking and sequencing have completed. A low voltage on the power good input after an adjustable timeout period causes load disconnect. A low voltage on the fault I/O causes immediate load disconnect. Until it is reset, a fault latch prevents tracking and keeps the loads disconnected.ApplicationsVCOREand VI/OSupply TrackingMicroprocessor, DSP and FPGA SuppliesServersCommunications Systems

The LTC2927 provides a simple solution to power supply tracking and sequencing requirements. By selecting a few resistors, the supply can be configured to ramp-up and ramp-down with differing ramp rates, voltage offsets, or time delays relative to other supplies or a master signal.By forcing current into a feedback node of an independent supply, the LTC2927 causes the output to track a ramp signal without inserting any pass element losses. Because the current is controlled in an open-loop manner, the LTC2927 does not affect the transient response or stability of the supply. The compact solution at point of load minimizes the trace length of the DC/DC circuit sensitive FB node. Furthermore, it presents a high impedance when power-up is complete, effectively removing it from the DC/DC circuit.ApplicationsVCORE and VI/O Supply TrackingMicroprocessor, DSP and FPGA SuppliesMultiple Supply SystemsPoint-of-Load Supplies

The LTC2928 is a four channel cascadable power supply sequencer and high accuracy supervisor. Sequencing thresholds, order and timing are configured with just a few external components, negating the need for PC board layout or software changes during system development. Multiple LTC2928s may be easily connected to sequence an unlimited number of power supplies.Sequence outputs control supply enable pins or N-channel pass gates. Precision input comparators with individual outputs monitor power supply voltages to 1.5% accuracy. Supervisory functions include undervoltage and overvoltage monitoring and reporting as well as μP reset generation.RSTmay be forced high to complement margin testing.Application faults, whether internally or externally generated, can shutdown all controlled supplies. The type and source of faults are reported for diagnosis. Individual channel controls are available to independently exercise enable outputs and supervisory functions.A high voltage input allows the LTC2928 to be powered from voltages as high as 16.5V. A buffered reference output permits single negative power supply sequencing and monitoring operations.APPLICATIONSNetwork/Telecom InfrastructureSequencing for Multiple I/O and Core VoltagesPower Management

The LTC2930 is a configurable supply monitor for systems with up to six supply voltages. One of 16 preset or adjustable voltage monitor combinations can be selected using an external resistive divider connected to the mode select pin. The preset voltage thresholds are accurate to ±1.5% over temperature. The LTC2930 also features adjustable inputs with a 0.5V nominal threshold.The reset timeout period is adjustable using an external capacitor. A reset event may be generated with a manual reset button on the manual reset input. Tight voltage threshold accuracy and glitch immunity ensure reliable reset operation without false triggering. TheRSToutput is guaranteed to be in the correct state for VCCdown to 1V and may be externally pulled up to an external voltage.The 52μA supply current makes the LTC2930 ideal for power conscious systems and it may be configured to monitor fewer than six inputs.ApplicationsDesktop and Notebook ComputersMultivoltage SystemsTelecom EquipmentPortable Battery-Powered EquipmentNetwork ServersAutomotive

The LTC2932 is a configurable supply monitor for systems with up to six supply voltages. One of 16 preset or adjustable voltage monitor combinations can be selected using an external resistive divider connected to the mode select pin. The preset voltage thresholds are digitally configurable to 5%, 7.5%, 10%, or 12.5% below the nominal operating voltage. The LTC2932 also features adjustable inputs with a 0.5V nominal threshold. All six open-drain voltage comparator outputs are connected to separate pins for individual supply monitoring.The reset timeout period is adjustable using an external capacitor. TheRSToutput is guaranteed to be in the correct state for VCCdown to 1V and may be disabled during supply margin testing. Each status output has a weak internal pull-up and may be externally pulled up to an external voltage.The 52μA supply current makes the LTC2932 ideal for power conscious systems and the part may be configured to monitor less than six inputs.ApplicationsDesktop and Notebook ComputersMultivoltage SystemsTelecom EquipmentPortable Battery-Powered EquipmentNetwork ServersAutomotive

The LTC2934 ultra-low power voltage monitor provides system initialization, power-fail warning and reset generation functions. Low quiescent current (500nA typical) makes the LTC2934 an ideal choice for battery-operated applications.Precision power-fail and reset voltages can be configured independently. Early warning of an impending low voltage condition is provided at the power-fail output (PFO) when the PFI input falls below 0.4V. Supervisory circuits monitor the ADJ input and pullRSTlow when ADJ falls below 0.4V. When ADJ is rising from an under-threshold condition, an internal reset timer is started after exceeding the ADJ threshold by 5%. The reset timeout delays the return of theRSToutput to a high state. A pushbutton switch connected to theMRinput is typically used to force a manual reset. OutputsRSTandPFOare available with open-drain (LTC2934-1) or active pull-up circuits (LTC2934-2). Operating temperature range is from –40ºC to 85ºC.ApplicationsPortable EquipmentBattery-Powered EquipmentSecurity SystemsPoint-of-Sale DevicesWireless Systems

The LTC2935 ultra-low power voltage monitor provides system initialization, power-fail warning and reset generation functions. Low quiescent current (500nA typical) makes the LTC2935 an ideal choice for battery-operated applications.Three binary threshold-select inputs configure one of eight integrated reset thresholds, ranging from 1.6V to 3.45V in pre-determined increments. Early warning of an impending low voltage condition is provided at the powerfail output (PFO), whose threshold is above the configured reset threshold. Supervisory circuits monitor VCCand pull RST low when VCCdrops below the configured reset threshold. When VCCis rising from an under-threshold condition, an internal reset timer is started after exceeding the reset threshold by 5%. A 200ms reset timeout delays the return of the RST output to a high state. A pushbutton switch connected to the MR input is typically used to force a manual reset. Outputs RST and PFO are available with open-drain (LTC2935-1/LTC2935-3) or active pull-up (LTC2935-2/LTC2935-4) circuits. Operating temperature range is from –40°C to 85°C.ApplicationsPortable EquipmentBattery-Powered EquipmentSecurity SystemsPoint-of-Sale DevicesWireless Systems

The LTC2936 is an EEPROM configurable voltage supervisor which can simultaneously monitor up to six power supply voltage inputs. Each voltage detector offers I2C programmable overvoltage/undervoltage thresholds in various ranges and increments and a dedicated comparator output.Two general purpose inputs (GPI) can be configured as programmable manual reset (MR), UV disable (UVDIS), margin (MARG), Write Protect (WP) or auxiliary comparator (AUXC) inputs. Three general purpose pins (GPIO) can be configured for input or output operation. When configured as an input, a GPIO pin can be mapped to any other GPIO configured as output. The GPIO pins can also be configured asALERTor fault outputs. Faults can be configured with programmable delay-on-release times. Output type and polarity are also configurable.Status and history registers log faults and can be polled via the I2C interface. A fault snapshot is also backed up in internal EEPROM. All parameters are programmable via the I2C interface. Configuration EEPROM supports autonomous operation without additional software.ApplicationsHigh Availability Computer SystemsNetwork ServersTelecom EquipmentData Storage