MAX8677CETG+T Maxim Integrated Products, MAX8677CETG+T Datasheet - Page 18

• Manufacturer Part Number: MAX8677CETG+T
• Description: IC USB/AC ADP CHARGER 24-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8677CETG+T

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4.1 V ~ 6.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1.5A Dual-Input USB/AC Adapter Charger
and Smart Power Selector
When the MAX8677C is used in conjunction with a µP,
connect a pullup resistor between PREQ and the logic I/O
voltage to indicate charge status to the µP. Alternatively,
PREQ can sink up to 20mA for an LED indicator.
FLT is an open-drain, active-low output that goes low
during a battery fault. The fault state occurs when either
the prequal or fast-charge timer expires. The prequal
and fast-charge fault timers are set by C
While in fast-charge mode, a large system load or
device self-heating can cause the MAX8677C to
reduce charge current. Under these circumstances, the
fast-charge timer adjusts to ensure that adequate
charge time is still allowed. Consequently, the fast-
charge timer is slowed by 2x if charge current is
reduced below 50% of the programmed fast-charge
level. If charge current is reduced to below 20% of the
programmed level, the fast-charge timer is paused. The
fast-charge timer is not adjusted if the charger is in volt-
age mode where charge current reduces due to cur-
rent tapering under normal charging.
Figure 7. Thermistor Monitor Circuitry
18
______________________________________________________________________________________
R
R
CONNECTION
THERMISTOR
TS
T
ALTERNATE
t
t
PREQUAL
FSTCHG
Fault Output ( F F L L T T ) and Charge Timer
R
TP
=
=
300
30
min
min
R
T
×
×
0 068
R
0 068
TB
.
.
C
C
CT
CT
μ
μ
CT
CEN
GND
VL
THM
F
F
:
VL
0.74 VL
0.28 VL
0.03 VL
To exit a fault state, toggle CEN or remove and recon-
nect the input source(s). Note also that thermistor out-
of-range or on-chip thermal-limit conditions are not
considered faults.
When the MAX8677C is used in conjunction with a µP,
connect a pullup resistor between FLT and the logic I/O
voltage to indicate fault status to the µP. Alternatively,
FLT can sink up to 20mA for an LED indicator.
The THM input connects to an external negative tem-
perature coefficient (NTC) thermistor to monitor battery
or system temperature. Charging is suspended when
the thermistor temperature is out of range. The charge
timers are suspended and hold their state but no fault
is indicated. When the thermistor comes back into
range, charging resumes and the charge timer contin-
ues from where it left off. Connecting THM to GND dis-
ables the thermistor monitoring function. Table 3 lists
fault temperatures for different thermistors.
Since the thermistor monitoring circuit employs an exter-
nal bias resistor from THM to VL (R
thermistor is not limited only to 10kΩ (at +25°C).
Any resistance thermistor can be used as long as the
value of R
resistance. For example, with a 10kΩ at +25°C thermis-
tor, use 10kΩ at R
mistor, use 100kΩ.
ALL COMPARATORS 60mV HYSTERESIS
THERMISTOR CIRCUITRY
MAX8677C
TB
is equivalent to the thermistor’s +25°C
HOT
BYPASS THM
COLD
TB
, and with a 100kΩ at +25°C ther-
Thermistor Input (THM)
THM OK
DISABLE
CHARGER
TB
, Figure 7), the