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参数资料
| 型号： | LT3651EUHE-4.2#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | BATTERY CHARGE CONTROLLER, 1100 kHz SWITCHING FREQ-MAX, PQCC36 |
| 封装： | 5 X 6 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, QFN-36 |
| 文件页数： | 9/22页 |
| 文件大小： | 213K |
| 代理商： | LT3651EUHE-4.2#PBF |
LT3651-4.1/LT3651-4.2
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APPLICATIONS INFORMATION
When the internal timer is used for termination, bad bat-
tery detection is engaged. This fault detection feature
is designed to identify failed cells. A bad battery fault is
triggered when the voltage on BAT remains below the
precondition threshold for greater than one-eighth of a full
timer cycle (one-eighth end-of-cycle). A bad battery fault
is also triggered if a normally charging battery re-enters
precondition mode after one-eighth end-of-cycle.
When a bad battery fault is triggered, the charge cycle
is suspended, so the CHRG status pin becomes high
impedance. The FAULT pin is pulled low to signal a fault
detection. The RNG/SS pin is also pulled low during this
fault, to accommodate a graceful restart, in the event that
a soft-start function is incorporated (see the RNG/SS:
Soft-Start section).
Cycling the charger’s power or SHDN function initiates a
new charge cycle, but a LT3651 charger does not require
a reset. Once a bad battery fault is detected, a new timer
charge cycle initiates when the BAT pin exceeds the pre-
condition threshold voltage. During a bad battery fault,
1mA is sourced from the charger. Removing the failed
battery allows the charger output voltage to rise and initiate
a charge cycle reset. In that way removing a bad battery
resets the LT3651. A new charge cycle is started by con-
necting another battery to the charger output.
Battery Temperature Fault: NTC
The LT3651 can accommodate battery temperature moni-
toring by using an NTC (negative temperature coefficient)
thermistor close to the battery pack. The temperature
monitoring function is enabled by connecting a 10kΩ,
B = 3380 NTC thermistor from the NTC pin to ground. If
the NTC function is not desired, leave the pin unconnected.
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 LT3651
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 hysteresis that corresponds to 2.5°C.
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 condition
is relieved. The RNG/SS pin is also pulled low during this
fault, to accommodate a graceful restart in the event that
a soft-start function is being incorporated (see the RNG/
SS: Soft-Start section).
If higher operational charging temperatures are desired,
the temperature range can be expanded by adding series
resistance to the 10k NTC resistor. Adding a 0.91k (0TC)
resistor will increase the effective temperature threshold
to 45°C.
Thermal Foldback
The LT3651 contains a thermal foldback protection fea-
ture that reduces maximum charger output current if the
internal IC junction temperature approaches 125°C. In
most cases, on-chip temperature servos 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 (TIMER = 0V), the
LT3651 will suspend charging and enter standby mode
until the overtemperature condition is relieved.
Layout Considerations
The LT3651 switch node has rise and fall times that are
typically less than 10ns to maximize conversion efficiency.
These fast switch times require care in the board layout
to minimize noise problems. The philosophy is to keep
the physical area of high current loops small (the inductor
charge/discharge paths) to minimize magnetic radiation.
Keep traces wide and short to minimize parasitic inductance
and resistance and shield fast switching voltage nodes
(SW, BOOST) to reduce capacitive coupling.
The switched node (SW pin) trace should be kept as
short as possible to minimize high frequency noise. The
VIN capacitor (CIN) should be placed close to the IC to
minimize this switching noise. Short, wide traces on these
nodes minimize stray inductance and resistance. Keep the
BOOST decoupling capacitor in close proximity to the IC to
minimize ringing from trace inductance. Route the SENSE
and BAT traces together and keep the traces as short as
possible. Shielding these signals from switching noise
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3651EUHE-8.2#PBF | 制造商:Linear Technology 功能描述:IC CHRG MGMT LI-ION/LI-POL 36QFN 制造商:Linear Technology 功能描述:DP-Battery Charger, Monolithic 4A High Voltage Li-Ion Battery Charger |
| LT3651EUHE-8.2#TRPBF | 制造商:Linear Technology 功能描述:IC CHRG MGMT LI-ION/LI-POL 36QFN 制造商:Linear Technology 功能描述:DP-Battery Charger, Monolithic 4A High Voltage Li-Ion Battery Charger |
| LT3651EUHE-8.4#PBF | 制造商:Linear Technology 功能描述:IC CHRG MGMT LI-ION/LI-POL 36QFN 制造商:Linear Technology 功能描述:DP-Battery Charger, Monolithic 4A High Voltage Li-Ion Battery Charger |
| LT3651EUHE-8.4#TRPBF | 制造商:Linear Technology 功能描述:IC CHRG MGMT LI-ION/LI-POL 36QFN 制造商:Linear Technology 功能描述:DP-Battery Charger, Monolithic 4A High Voltage Li-Ion Battery Charger |
| LT3651IUHE-4.1#PBF | 制造商:Linear Technology 功能描述:Battery Charger Li-Ion/Li-Pol 4000mA 4.1V 36-Pin QFN EP 制造商:Linear Technology 功能描述:IC CHRG MGMT LI-ION/LI-POL 36QFN 制造商:Linear Technology 功能描述:DP-Battery Charger, Monolithic 4A High Voltage Li-Ion Battery Charger |
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