MC34675AEPR2 Freescale Semiconductor, MC34675AEPR2 Datasheet - Page 15

• 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 CYCLE
constant-current (CC), and constant-voltage (CV) charge
modes, as shown in
charge modes are also called fast-charge mode. When the
input voltage rises above an internal power-on-reset
threshold, the PPR pin outputs a low voltage to indicate the
power-supply presence. The charger starts with the trickle-
charge mode until the battery voltage is above 2.7V. The
CHG pin outputs logic low voltage at the beginning of the
trickle-charge mode. If the battery voltage is unable to rise
due to a battery failure, charging will remain in the trickle-
charge mode. When the battery voltage reaches the 2.7V
threshold, the 34675 softly changes to the CC mode. The soft
transition minimizes the input-voltage drop and reduces the
requirement of the input decoupling capacitance. When the
battery voltage reaches 4.2V, the 34675 enters the CV mode
and regulates the output voltage at 4.2V. The charge current
decreases gradually in the CV mode. When the current drops
to the EOC current threshold, the 34675 outputs logic high
level at the CHG pin to indicate that the charging is
completed.
CHARGE CURRENT SETTING
the CC mode current with the following equation:
Analog Integrated Circuit Device Data
Freescale Semiconductor
The 34675 uses the standard charge profile with trickle,
An external resistor between the ISET pin and ground sets
I
CHG
=
CHG
4.2V
I
2.7V
I
------------- -
R
TRKL
CHG
4000
ISET
Figure
Trickle
27. Both the CC and the CV
Constant Current
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
Figure 27. Charge Profile
Constant Voltage
Current
I
Charge
EOC
Voltage
Battery
continues to regulate and monitor the output to 4.2V. If
a load is connected in parallel with the battery, the
34675 will ensure that the charger continues to supply
the charge current, even if the charge cycle is
completed. If the load current exceeds the pre-
programmed CC mode current, the battery will supply
the additional current to the load, thereby reducing the
battery voltage. Once the battery voltage drops below
the recharge voltage, the 34675 returns to the fast
charge mode and indicates a logic low at the CHG pin.
34675 stops charging and enters disable mode.
monitors the input and the battery voltages
in Ω. I
pin is proportional to the charge current. The system may
measure the ISET pin voltage to monitor the actual charge
current during the whole charging cycle, using the following
equation:
where V
where R
1. V
2. V
3. EN pin is high
After the charge cycle is completed, the 34675
When one of the following three conditions happens, the
Figure 29
100mV
CHG
IN
IN
OS
ISET
-V
> V
is in Amps. In addition, the current out of the ISET
BAT
is the offset voltage for the comparator that
shows the complete charge cycle state diagram.
OVP
is the resistor between the ISET pin and ground
< V
>I
I
LOAD
CHG
OS
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
TIME
TIME
34675
15