MAX8934GETI+ Maxim Integrated Products, MAX8934GETI+ Datasheet - Page 21

• Manufacturer Part Number: MAX8934GETI+
• Description: IC LI BATT CHARGER DUAL 28TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8934GETI+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

fast-charge current setting. Note that if charge current
falls to I
the charger does not enter the DONE state. For the char-
ger to enter the DONE state, the charge current must be
less than I
and the input or thermal limiter must not be reducing the
charge current. The charger exits the DONE state, and
fast-charge resumes if the battery voltage subsequently
drops 104mV or if CEN is cycled.
CHG is an open-drain, active-low output that is low dur-
ing charging. CHG is low when the battery charger is in
its prequalification and fast-charge states. When charge
current falls to the charge termination threshold (I
and the charger is in voltage mode, CHG goes high
impedance. CHG goes high impedance if the thermistor
causes the charger to enter temperature suspend mode.
When the MAX8934G is used with a microprocessor (FP),
connect a pullup resistor between CHG and the logic I/O
voltage to indicate charge status to the FP. Alternatively,
CHG can sink up to 20mA for an LED indicator.
DONE is an open-drain, active-low output that goes
low when charging is complete. The charger enters its
DONE state 15s after the charge current falls to the
Figure 4. Monitoring the Battery Charge Current with V ISET
V
ISET
1.5
Dual-Input Linear Charger, Smart Power Selector
0
with Advanced Battery Temperature Monitoring
DISCHARGING
DONE
DONE
as a result of the input or thermal limiter,
, the charger must be in voltage mode,
______________________________________________________________________________________
BATTERY CHARGING CURRENT (A)
CHARGE CURRENT WITH V
0
MONITORING THE BATTERY
Charge DONE Output (DONE)
Charge Status Outputs
Charge Output (CHG)
ISET
2000 (1.5V/R ISET )
DONE
)
charge-termination threshold (I
in voltage mode. The charger exits the DONE state, and
fast-charge resumes, if the battery voltage subsequently
drops 104mV, or if input power or CEN is cycled. When
the MAX8934G is used in conjunction with a FP, con-
nect a pullup resistor between DONE and the logic I/O
voltage to indicate charge status to the FP. Alternatively,
DONE 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 MAX8934G 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 pro-
grammed 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 voltage mode where charge current
reduces due to current tapering under normal charging.
To exit a fault state, toggle CEN or remove and reconnect
the input source(s). Note also that thermistor out of range
or on-chip thermal-limit conditions are not considered
faults. When the MAX8934G is used in conjunction with a
FP, connect a pullup resistor between FLT and the logic
I/O voltage to indicate fault status to the FP. Alternatively,
FLT can sink up to 20mA for an LED indicator.
The MAX8934G thermistor monitor is configured to
execute JEITA recommendations regarding Li+/Li-Poly
battery charging by adjusting the fast charge current
and/or the charge termination voltage accordingly (see
Figure 6 ). Connect the THM input to an external negative
temperature coefficient (NTC) thermistor to monitor bat-
tery or system temperature. Since the thermistor monitor-
ing circuit employs an external bias resistor from THM
to THMSW, the thermistor is not limited only to 10kI (at
FAST CHARGE: t
PREQUAL: t
Fault Output (FLT) and Charge Timer
TOP OFF:t
−
PQ
FC
=
180min
=
TO
300min
DONE
Thermistor Monitor
=
15s
×
) and the charger is
0.068 F
×
C
0.068 F
CT
CT
C
F
:
CT
F
21