BC3770 Datasheet, PDF (13/45 Pages) Freescale Semiconductor, Inc – 2.0 A Switch-Mode Charger

5 Functional Device Operation
5.1 Introduction
The BC3770 is a fully programmable switching charger with a single-input for USB/DCP adapter and a dual-path output for single-cell Li-
Ion and Li-Polymer batteries. The dual-path output allows mobile applications with a fully discharged or dead battery to boot up the system
through the VSYS output. High-efficiency and switch-mode operation of the BC3770 reduce thermal dissipation and allows the battery to
charge faster with a higher current capability. The BC3770 supports single input up to 20 V max. absolute voltage and charges the battery
with the current up to 2.0 A. Owing to a high-efficiency in a wide range of input voltages and charging currents, the switch mode charger
is a good choice for fast charging with less power loss and better thermal management than a linear charger. The charging parameters
and operating modes are fully programmable over an I²C interface that operates up to 400 kHz in full speed. The BC3770 features a highly
integrated synchronous switch-mode charger, intelligent power-path, VSYS stable control scheme in overload condition, and an automatic
battery detection function. The charger and boost regulator circuit switches at 1.5 MHz, to minimize the size of external passive
components.
To ensure USB compliance and minimize charging time, the input current is able to be limited to the value set through the I²C. The setting
of charge top-off current is also programmable over I²C.
The BC3770 provides battery charging in four modes: trickle, pre-charge, fast charge (constant current), and full-charge (constant
voltage). The charging restart circuit automatically restarts the fast-charge cycle in full-charge mode when the battery falls below an
internal threshold over the deglitch time and detected top-off threshold. Input and charge status are reported to the processors through
the interrupt pin, INTB. Charge current is reduced when the die temperature reaches 100 °C, while the system current is maintained. The
BC3770 is able to operate as a boost regulator for USB-OTG devices over I²C.
5.2 Features
• Dual-path output to power-up system in dead battery
• Single Input for USB/TA
• High-efficiency synchronous switching regulator
• 20 V maximum withstanding input voltage
• Minimize the charging time with remote sense
• Up to 2.0 A load current for system or battery
• Programmable charge parameters via I²C compatible interface
• Fast charge current
• Charge termination current
• Battery regulation voltage
• Pre-charge current
• Fast charge threshold voltage
• Charge reduction threshold voltage
• 400 kHz full-speed I²C interface
• 1.5 MHz switching frequency
• Charge reduction mode for maximizing charging efficiency
• Protection
• Thermal protection
• Thermal regulation
• Input/output overvoltage protection
• Adaptive input current limit protection (AICL)
• Reverse leakage protection
• No battery detection over pin detection
• Battery OVP protection
• Overcurrent protection in discharge mode
• Boost mode operation for USB OTG
• Output voltage: 5.0 V to 5.2 V, programmable at 900 mA
BC3770
13
Analog Integrated Circuit Device Data
Freescale Semiconductor