LTM8062IV#PBF Linear Technology, LTM8062IV#PBF Datasheet - Page 15

• Manufacturer Part Number: LTM8062IV#PBF
• Description: IC, BATT CHRG, Li-Ion, Li-Polymer, 2A, LGA77
• Manufacturer: Linear Technology

Specifications of LTM8062IV#PBF

• Battery Type: Li-Ion, Li-Polymer
• Input Voltage: 32V
• Battery Charge Voltage: 14.4V
• Charge Current Max: 2A
• Battery Ic Case Style: LGA
• No. Of Pins: 77
• No. Of Series Cells: 1

APPLICATIONS INFORMATION
impedance. The FAULT pin is pulled low to signal that a
fault has been detected.
Cycling the charger’s power or shutdown function initiates
a new charge cycle, but the LTM8062 charger does not
require a manual reset. Once a bad-battery fault is detected,
a new timer charge cycle initiates if the BAT pin exceeds
the precondition threshold voltage. During a bad-battery
fault, a small current is sourced from the charger; removing
the failed battery allows the charger output voltage to rise
above the preconditioning threshold voltage and initiate a
charge cycle reset. A new charge cycle is started by con-
necting another battery to the charger output.
Battery Temperature Fault: NTC
The LTM8062 can accommodate battery temperature
monitoring by using an NTC (negative temperature
coefficient) thermistor close to the battery pack. The
temperature monitoring function is enabled by connect-
ing a 10kΩ, β ≈ 3380 NTC thermistor from the NTC pin
to ground. If the NTC function is not desired, leave the
pin open. The NTC pin sources 50μA, and monitors the
voltage dropped across the 10kΩ thermistor. When the
voltage on this pin is above 1.36V (0°C) or below 0.29V
(40°C), the battery temperature is out of range, and the
LTM8062 triggers an NTC fault. The NTC fault condition
remains until the voltage on the NTC pin corresponds to
a temperature within the 0°C to 40°C range. Both hot and
cold thresholds incorporate 20% hysteresis, which equates
to about 5°C. If higher operational charging temperatures
are desired, the temperature range can be expanded by
adding series resistance to the 10k NTC resistor. Adding
a 909Ω resistor will increase the effective temperature
threshold to 45°C, for example.
During an NTC fault, charging is halted and both status
pins are pulled low. If timer termination is enabled, the
timer count is suspended and held until the fault condi-
tion is cleared.
Thermal Foldback
The LTM8062 contains a thermal foldback protection feature
that reduces charge current as the IC junction temperature
approaches 125°C. In most cases, on-chip temperatures
servo such that any overtemperature conditions are relieved
with only slight reductions in maximum charge current.
In some cases, the thermal foldback protection feature
can reduce charge currents below the C/10 threshold.
In applications that use C/10 termination (TMR = 0V), the
LTM8062 will suspend charging and enter standby mode
until the overtemperature condition is relieved.
PCB Layout
Most of the headaches associated with PCB layout have
been alleviated or even eliminated by the high level of
LTM8062 integration. The LTM8062 is nevertheless
a switching power supply, and care must be taken to
minimize EMI and ensure proper operation. Even with the
high level of integration, you may fail to achieve specified
operation with a haphazard or poor layout. See Figure 7
for a suggested layout. Ensure that the grounding and
heat sinking are acceptable.
1. Place the C
2. If used, place the C
3. Place the C
(OPTIONAL)
THERMAL VIAS
and GND connection of the LTM8062.
to the BAT and GND connection of the LTM8062.
ground current flows directly adjacent or underneath
the LTM8062.
C
BAT
BAT
Figure 7. Suggested Layout and Via Placement
IN
IN
and C
capacitor as close as possible to the V
GND
BAT
BAT
(if used) capacitors such that their
capacitor as close as possible
ADJ
LTM8062
C
IN
RUN V
V
IN
INREG
GND
15
V
INA
8062fa
8062 F07
IN