參數(shù)資料
型號(hào)： MAX1644
廠商： Maxim Integrated Products, Inc.
英文描述： Advanced Chemistry-Independent, Level 2 Battery Charger with Input Current Limiting
中文描述： 2A、低電壓、降壓型穩(wěn)壓器，內(nèi)置同步整流與開關(guān)
文件頁(yè)數(shù)： 26/32頁(yè)
文件大?。?/td> 183K
代理商： MAX1644
M
Advanc ed Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
26
______________________________________________________________________________________
driver turns on, BST rises to one diode voltage below
DLOV.
Filter DLOV with an RC circuit whose cutoff frequency
is about 50kHz. The configuration in Figure 1 intro-
duces a cutoff frequency of around 48kHz.
f = 1 / 2
π
RC = 1 / (2
·
π
·
33
·
0.1μF) = 48kHz
T hermistor Comparators
Four thermistor comparators evaluate the voltage at the
THM input to determine the battery temperature. This
input is meant to be used with the internal thermistor
connected to ground inside the battery pack. Connect
the output of the battery thermistor to THM. Connect a
resistor from THM to V
DD
. The resistor-divider sets the
voltage at THM. When the charger is not powered up,
the battery temperature can still be determined if V
DD
is
powered from an external voltage source.
T hermistor Bits
Figure 9 shows the expected electrical behavior of a
103ETB-type thermistor (nominally 10k
at +25°C ±5%
or better) to be used with the MAX1645:
THERMISTOR_OR bit is set when the thermistor
value is >100k
. This indicates that the thermistor is
open or a battery is not present. The charger is set to
POR, and the BATTERY_PRESENT bit is cleared.
THERMISTOR_COLD bit is set when the thermistor
value is >30k
. The thermistor indicates a cold bat-
tery. This bit does not affect the charge.
THERMISTOR_HOT bit is set when the thermistor
value is <3k
. This is a latched bit and is cleared by
removing the battery or sending a POR with the
ChargerMode() command. The charger is stopped
unless the HOT_STOP bit is cleared in the
ChargerMode() command.
THERMISTOR_UR bit is set when the thermistor
value is <500
(i.e., THM is grounded).
Multiple bits may be set depending on the value of the
thermistor (e.g., a thermistor that is 450
will cause
both the THERMISTOR_HOT and the THERMISTOR_UR
bits to be set). The thermistor may be replaced by
fixed-value resistors in battery packs that do not require
the thermistor as a secondary fail-safe indicator. In this
case, it is the responsibility of the battery pack to
manipulate the resistance to obtain correct charger
behavior.
Load and S ourc e S witc h Drivers
The MAX1645 can drive two P-channel MOSFETs to
eliminate voltage drops across the Schottky diodes,
which are normally used to switch the load current from
the battery to the main DC source:
The source switch P1 is controlled by PDS. This P-
channel MOSFET is turned on when CVS rises to
300mV above BATT and turns off when CVS falls to
100mV above BATT. The same signal that controls
the PDS also sets the POWER_FAIL bit in the
Charger Status() register. See Operating Conditions.
The load switch P2 is controlled by PDL. This P-
channel MOSFET is turned off when the CVS rises to
100mV below BATT and turns on when CVS falls to
300mV below BATT.
Dropout Operation
The MAX1645 has a 99.99% duty-cycle capability with
a 10ms maximum on-time and 1μs off-time. This allows
the charger to achieve dropout performance limited
only by resistive losses in the DC-DC converter compo-
nents (P1, R1, N1, R2; see Figure 1). The actual
dropout voltage is limited to 300mV between CVS and
BATT by the power-fail comparator (see Operating
Conditions).
1000
100
10
R
)
1
0.1
-40
-50
-30-20-10 0 10 20 30 40 50 60 70 80 90 100 110
TEMPERATURE (°C)
Figure 9. Typical Thermistor Characteristics
相關(guān)PDF資料
PDF描述
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1644EAE 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX1644EAE/GH9 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX1644EAE/GH9-T 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX1644EAE+ 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 2A Step-Dow w/Synch Rectification RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX1644EAE+T 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 2A Step-Dow w/Synch Rectification RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
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