Analog Integrated Circuit Device Data

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13

Freescale Semiconductor

BC3770

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

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.

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

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

• Fast charge current

• Charge termination current

• Battery regulation voltage

• Pre-charge current

• Fast charge threshold voltage

• Charge reduction threshold voltage

•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