MC34675AEPR2 Freescale Semiconductor, MC34675AEPR2 Datasheet - Page 16

• Manufacturer Part Number: MC34675AEPR2
• Description: IC BATTERY CHARGER 28V 8-UDFN
• Manufacturer: Freescale Semiconductor

Specifications of MC34675AEPR2

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 2.6 V ~ 6.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-UDFN
• Product: Charge Management
• Output Voltage: 4.2 V
• Output Current: 1000 mA
• Operating Supply Voltage: 2.6 V to 6.6 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CHARGE CURRENT LIMITATION
battery (V
R
less than the programmed CC mode current I
case, the 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 external power supply is off. V
protection 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 voltage, leaving it float, or
shorting it to ground, will enable the charger if the input
voltage is in the power-good range. Whenever the EN pin is
driven to a high voltage, the charger is disabled. When the
charger is disabled, the BAT pin does not output voltage and
current, the leakage current into the BAT pin is less than
1.0μA, the output of the CHG pin is high, and the voltage at
the ISET pin is zero. If the input voltage is in the power-good
range when the charger is disabled, the output of the PPR is
still low to indicate the input voltage status and the DET pin
outputs voltage as well.
16
34675
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
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 34675 accepts up to a 28V DC input. When all of the
The charge-enable input, EN, has a weak internal pull-
I
BAT
IN
IN
IN
OS
is the on resistance of the power MOSFET, may be
> V
-V
< V
IN
=
-V
is the offset voltage for the comparator that
BAT
POR
OVP
V
-------------- I
BAT
1.0V
> V
ISET
) is low, (V
section for more information).
OS
⋅
CHG
IN
- V
BAT
OVP
) / R
Charge Current
is the over-voltage
IN
DS(ON)
- V
BAT
CHG
, where
) / R
. In this
OS
DS(ON)
is for
.
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 of sinking at least 9.0mA of current
when outputting a low voltage to drive an external LED.
CHARGE STATUS INDICATORS
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 a high-impedance as well. The CHG pin has at least
9.0mA current-sinking capability to drive an external LED, the
same as the PPR pin.
CHARGE CURRENT THERMAL FOLDBACK
charge current, when the die temperature reaches 120°C, to
prevent further temperature rise. This feature protects the
34675 from over-temperature failure, and allows the user to
push the limits of the power-handling capability of a given
circuit board, without the risk of damaging the 34675. 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.
LINEAR REGULATOR
current capability. The output is turned on when the input
voltage is above the POR threshold but lower than the OVP
threshold. The output is independent of any other signals in
the charger, such as the enable (EN) input.
output starts to output a voltage, but is in the dropout mode.
The output voltage is determined by the dropout voltage. As
the input voltage rises above the regulation voltage, the
output is regulated at 4.85V. When the input voltage further
rises above the OVP rising threshold, the linear regulator is
turned off, and the output voltage drops to zero with an
internal 200kΩ pull-down resistor. The output voltage
resumes to 4.85V when the input voltage falls below the OVP
falling threshold. The output voltage versus the input voltage
is shown in
POR rising and falling threshold. The V
the OVP rising and falling threshold. An output decoupling
capacitor of 0.1μF to 1.0μF is required between the DET pin
and ground for the stability of the linear regulator.
When V
The 34675 has one charge-status indicator, CHG. CHG
An internal thermal feedback loop begins to reduce the
The linear regulator provides a 4.85V output with 10mA
When the input reaches the rising POR threshold, the DET
IN
Figure
is applied and the voltage is above the power-
28, where the V
Analog Integrated Circuit Device Data
POR
), the PPR pin outputs a low
PORR
Freescale Semiconductor
OVPR
and V
and V
PORF
OVPF
are the
are