mc34671aep/r2 Freescale Semiconductor, Inc, mc34671aep/r2 Datasheet - Page 15

• Manufacturer Part Number: mc34671aep/r2
• Description: Mc34671 600ma High-input Voltage Charger For Single-cell Li-ion And Li-polymer Batteries
• Manufacturer: Freescale Semiconductor, Inc

voltage to monitor the actual charge current as given in
equ. 1
CHARGE CURRENT LIMITATION
battery (V
R
less than the programmed CC-mode current I
charge current is limited by (V
battery is too high, the large power dissipation may lead to
the charge current thermal foldback operation, due to the die
temperature regulation. The charge current is reduced to
prevent further temperature rise (See
Thermal Foldback
DC INPUT VOLTAGE
following conditions are satisfied, the input is in a power-good
range for the charger to start charging. The conditions
include:
where V
monitors the input and the battery voltages. The V
preventing the reverse leakage current from the battery when
the power supply is off. V
threshold. When the DC input voltage is above the over-
voltage protection threshold, the charger is disabled
internally. The 28V input voltage rating eliminates the need of
any additional input over-voltage protection circuitry.
CHARGE-ENABLE INPUT
down current. Driving it to a low logic voltage, leaving it
floating, or shorting it to the ground, will enable the charger if
the input voltage is in the power-good range. Whenever the
Analog Integrated Circuit Device Data
Freescale Semiconductor
DS(ON)
1. V
2. V
3. V
The charge current is limited by multiple factors.
When the voltage difference between the input and the
When the voltage difference between the input and the
The MC34671 accepts up to 28V DC input. When all of the
The charge-enable input, EN, has a weak internal pull-
during the whole charging cycle.
IN
IN
IN
OS
is the on resistance of the power MOSFET, may be
> V
- V
< V
IN
is the offset voltage for the comparator that
- V
BAT
POR
OVP
BAT
> V
) is low, (V
for more information).
OS
OVP
IN
IN
is the over-voltage protection
- V
- V
BAT
BAT
) / R
) / R
Charge Current
DS(ON)
DS(ON)
CHG
in this case.
, where
. The
OS
is for
EN pin is driven to a high logic voltage, the charger is
disabled.
INPUT POWER PRESENCE INDICATOR
on-reset voltage threshold (V
voltage to indicate the input power presence. The PPR output
is only controlled by the input voltage. All other functions,
such as the EN pin, the over-voltage protection, and the VIN-
BAT comparator, do not affect the PPR output. The PPR pin
is capable to sink at least 12.0mA of current when outputting
a low voltage to drive an external LED.
CHARGE STATUS INDICATORS
FAST. CHG outputs a low voltage when the charger is
enabled and the charging is in progress. When the charge
cycle completes, CHG outputs high-impedance. If the
charger is disabled or the input voltage is out of the power-
good range, the CHG pin outputs high-impedance as well.
The CHG pin has at least 12.0mA of current-sinking
capability to drive an external LED, same as the PPR pin.
mode or not. When the charger is on and the battery voltage
is higher than the trickle-mode threshold, the charger enters
the fast-charge mode and FAST outputs a low voltage. The
open-drain FAST pin requires a pull-up resistor to output the
logic signal. If the charger is in the trickle-charge mode or is
disabled, or when the input voltage is out of the power-good
range, the FAST pin outputs high-impedance.
CHARGE CURRENT THERMAL FOLDBACK
charge current when the die temperature reaches 110°C to
prevent further temperature rise. This feature protects the
MC34671 from over-temperature failures and allows the user
to push the limits of the power handling capability of a given
circuit board without the risk of damaging the MC34671. The
charge current can be programmed according to the typical
(not the worst-case) ambient temperature with the assurance
that the charger will automatically reduce the current in worst-
case conditions.
When V
The MC34671 has two charge status indicators, CHG and
FAST indicates whether the MC34671 is in the fast-charge
An internal thermal feedback loop begins to reduce the
IN
is applied and the voltage is above the power-
FUNCTIONAL DEVICE OPERATION
POR
), the PPR pin outputs a low
OPERATIONAL MODES
34671
15