Analog Devices Inc./Maxim Integrated

The LT3640 is a dual channel, current mode monolithic buck switching regulator with a power-on reset and a watchdog timer. Both regulators are synchronized to a single oscillator with an adjustable frequency (350kHz to 2.5MHz). At light loads, both regulators operate in low ripple Burst Mode®to maintain high efficiency and low output ripple.The high voltage channel is a nonsynchronous buck with an internal 2.4A top switch that operates from an input of 4V to 35V; a 36.5V OVLO protects the device to 55V. The low voltage channel operates from an input of 2.5V to 5.5V. Internal synchronous power switches provide high efficiency without the need of external Schottky diode. Both channels have cycle-by-cycle current limit, providing protection against shorted outputs.The power-on reset and watchdog timeout periods are both adjustable using external capacitors. The window mode watchdog timer flags when the μP pulses group too close together or too far apart.The LT3640 is available in a 28-pin 4mm × 5mm QFN package and 28-pin TSSOP package. Both packages have an exposed pad for low thermal resistance.ApplicationsIndustrial Power SuppliesAutomotive Electronic Control Units

The LT3641 is a dual channel, current mode monolithic buck switching regulator with a power-on reset and a watchdog timer. Both regulators are synchronized to a single oscillator with an adjustable frequency (350kHz to 2.5MHz). At light loads, both regulators operate in low ripple Burst Mode®to maintain high effi ciency and low output ripple.The high voltage channel is a nonsynchronous buck with an internal 2.4A top switch that operates from an input of 4V to 42V and input transient protection to 55V. The low voltage channel operates from an input of 2.5V to 5.5V. Internal synchronous power switches provide high effi ciency without the need of external Schottky diode. Both channels have cycle-by-cycle current limit, providing protection against shorted outputs.The power-on reset and watchdog timeout periods are both adjustable using external capacitors. The window mode watchdog timer fl ags when the μP pulses group too close together or too far apart.The LT3641 is available in a 28-pin 4mm × 5mm QFN package and 28-pin TSSOP package. Both packages have an exposed pad for low thermal resistance.ApplicationsIndustrial Power SuppliesAutomotive Electronic Control Units

The LT3651-8.2/LT3651-8.4 are 2-cell, 4A Li-Ion/Polymer battery chargers that operate over a 9V to 32V input voltage range. An efficient monolithic average current mode synchronous switching regulator provides constant current, constant voltage charging with programmable maximum charge current. A charging cycle starts with battery insertion or when the battery voltage drops 2.5% below the float voltage. Charger termination is selectable as either charge current or internal safety timer timeout. Charge current termination occurs when the charge current falls to one-tenth the programmed maximum current (C/10). Timer based termination is typically set to three hours and is user programmable (charging continues below C/10 until timeout). Once charging is terminated, the LT3651-8.2/LT3651-8.4 supply current drops to 85μA into a standby mode.The LT3651-8.2/LT3651-8.4 offer several safety features. A discharged battery is preconditioned with a small trickle charge and generates a signal if unresponsive. A thermistor monitors battery temperature, halting charging if out of range. Excessive die temperature reduces charge current. Charge current is also reduced to maintain constant input current to prevent excessive input loading. The LT3651-8.2/LT3651-8.4 are available in a 5mm × 6mm 36-lead QFN package.Float VoltageLT3651-4.14.1VLT3651-4.24.2VLT3651-8.28.2VLT3651-8.48.4VApplicationsIndustrial Handheld Instruments12V to 24V Automotive and Heavy EquipmentDesktop Cradle ChargersNotebook Computers

The LT3651 is a 1 cell 4A Li-Ion/Polymer battery charger that operates with input voltages up to 32V. An efficient monolithic average current mode synchronous switching regulator provides constant current, constant voltage charging with programmable maximum charge current. A charging cycle starts with battery insertion or when the battery voltage drops 2.5% below the float voltage. Charger termination is selectable as either charge current or internal safety timer timeout. Charge current termination occurs when the charge current falls to one-tenth the programmed maximum current (C/10). Timer based termination is typically set to three hours and is user programmable (charging continues below C/10 until timeout). Once charging is terminated, the LT3651 supply current drops to 85μA into a standby mode.The LT3651 offers several safety features. A discharged battery is preconditioned with a small trickle charge and generates a signal if unresponsive. A thermistor monitors battery temperature, halting charging if out of range. Excessive die temperature reduces charge current. Charge current is also reduced to maintain constant input current to prevent excessive input loading.The LT3651 is available in a 5mm × 6mm 36-pin QFN package.Float VoltageLT3651-4.14.1VLT3651-4.24.2VLT3651-8.28.2VLT3651-8.48.4VApplicationsIndustrial Handheld Instruments12V to 24V Automotive and Heavy EquipmentDesktop Cradle ChargersNotebook Computers