Document Number: MC34673
Rev. 1.0, 01/2008
High Input Voltage 1.2A Charger
for Single-cell Li-Ion Batteries
The MC34673 is a cost-effective fully-integrated battery charger for
Li-Ion or Li-Polymer batteries. The high input voltage, up to 28V,
eliminates the input over-voltage protection circuit required in handheld
devices such as PDAs, cell phones, portable video game players and
digital still cameras.
A typical charge cycle includes trickle, constant-current (CC) and
constant-voltage (CV) charge modes. The CC-mode current is
programmable up to 1.2A with an external resistor. The voltage across
the external resistor is also used to monitor the actual charge current.
The constant voltage is fixed at 4.2V with 0.7% accuracy over a -20°C
to 70°C temperature range. The trickle-mode current is preset to 20%
of the CC-mode current when the battery voltage is lower than the
trickle-mode threshold. The end-of-charge (EOC) current threshold is
preset to 10% of the CC-mode current to save the board space and
cost. A charge current thermal foldback feature limits the charge
current when the IC internal temperature rises to a preset threshold.
The MC34673 also protects the system with its input over-voltage
protection (OVP) feature. In addition, the MC34673 has a 2.6V falling
power-on-reset (POR) threshold, making it perfect to work with current
limited power supplies. Three indication pins (PPR, CHG and FAST)
can be simply interfaced to a microprocessor or LEDs. When no power
supply is connected, or when disabled, the charger draws less than
1.0µA leakage current from the battery.
POWER MANAGEMENT IC
EP SUFFIX (PB-FREE)
-40°C to 85°C
• No external MOSFET, reverse-blocking diode or current-sense resistor are required
• Guaranteed maximum 1.2A programmable CC-mode current
• ±0.7% voltage accuracy over -20°C to 70°C
• ±6% current accuracy over -40°C to 85°C
• 28V maximum voltage for the power input with 6.8V over-voltage protection threshold
• 2.6V minimum input operating voltage
• Trickle charge for fully discharged batteries
• Charge current monitor
• Charge current thermal foldback
• Pb-free packaging designated by suffix code EP
Figure 1. 34673 Simplified Application Diagram
* This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Freescale Semiconductor, Inc., 2007-8. All rights reserved.