PMIC ideal for use with low-power portable devices
Linear Technology
LTC3553 PMIC
Linear Technology has introduced a micro-power multifunction power management integrated circuit (PMIC) solution for personal navigation devices, media players and handheld medical/industrial devices.
The LTC3553 PMIC has been developed for portable Li-ion/polymer battery-based applications.
The device integrates a USB-compatible linear Powerpath manager, a standalone battery charger, a synchronous buck regulator, a low-dropout (LDO) linear regulator and a pushbutton controller in an ultra-thin (0.55mm) 3 x 3mm QFN package.
A pin-selectable standby mode reduces battery drain current to just 12uA while keeping all outputs in regulation, extending battery runtime.
The LTC3553 is suitable for low-power portable device applications.
Its Powerpath manager, with automatic load prioritisation, manages the transition between multiple input sources to power the load, while delivering up to 400mA of battery charge current from a USB port or a 5V wall-adapter input.
The input current limit is pin selectable and internally set (no external resistor is required).
The LTC3553 is compatible with inputs of up to 5.5V (7V maximum transient for added robustness).
The device's 'instant-on' operation ensures immediate system load power when USB or a 5V wall supply is available, even with a fully discharged battery.
Autonomous operation simplifies the design, eliminating the need for an external microprocessor for charge termination.
The internal 240mohm diode provides a low-loss power path to the load when input current is limited or unavailable.
An NTC function is also available for temperature-qualified charging.
The LTC3553's integrated synchronous buck regulator delivers up to 200mA output current with a regulated output voltage that is adjustable down to 0.8V.
The 1.125MHz switching frequency reduces output ripple while enabling the use of tiny low-cost capacitors and inductors measuring less than 1mm in height.
Low RDS(ON) internal switches enable buck efficiencies as high as 93 per cent.
Buck efficiency is optimised in Burst Mode operation, drawing only 22uA of supply current, while standby mode can be used for 'keep-alive' applications, reducing the buck's quiescent current to 1.5uA (less than 1uA in shutdown).
The LDO regulator provides up to 150mA of output current.
Regulated output voltage is adjustable down to 0.8V, independent of the buck output.
The LDO's power input is accessible as a pin, allowing LDO efficiency to be increased in some applications by powering the LDO from the buck output.
Both the buck and LDO are stable with tiny ceramic output capacitors, eliminating the need for larger, expensive tantalum or electrolytic capacitors.
The integrated pushbutton controller enables one-button power-up and power-down sequencing as well as a status signalling output indicating the button state.
The controller also provides a Hard Reset state for software lockup recovery or to enable an ultra-low battery drain state (typically 0.2uA) for the device.
The LTC3553 is available from stock in a compact, ultra-low-profile (0.55mm) 3 x 3mm UTQFN-20 package.
Pricing starts at USD2.25 (GBP1.48) each for 1,000-piece quantities.
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