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参数资料
| 型号： | MAX1909ETI |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | Multichemistry Battery Charger with Automatic System Power Selector |
| 中文描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, QCC28 |
| 封装： | 5 X 5 MM, 0.80 MM HEIGHT, MO-220-WHHD-1, TQFN-28 |
| 文件页数： | 17/29页 |
| 文件大小： | 551K |
| 代理商： | MAX1909ETI |
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M
Multichemistry Battery Charger with Automatic
System Power Selector
______________________________________________________________________________________
17
current. The sense resistor
’
s I
2
R power loss reduces
charger efficiency. Adjusting ICTL to drop the voltage
across the current-sense resistor improves efficiency,
but may degrade accuracy due to the current-sense
amplifier
’
s input offset error. The charge-current error
amplifier (GMI) is compensated at the CCI pin. See the
Compensation
section.
Setting the Input Current Limit
The total input current, from a wall cube or other DC
source, is the sum of the system supply current and the
current required by the charger. The MAX1909 reduces
the source current by decreasing the charge current
when the input current exceeds the set input current
limit. This technique does not truly limit the input current.
As the system supply current rises, the available charge
current drops proportionally to zero. Thereafter, the total
input current can increase without limit.
An internal amplifier compares the differential voltage
between CSSP and CSSN to a scaled voltage set with
the CLS input. V
CLS
can be driven directly or set with a
resistive voltage-divider between REF and GND.
Connect CLS to REF to set the input current-limit sense
voltage to the maximum value of 75mV. Calculate the
input current as follows:
V
CLS
determines the reference voltage of the GMS
error amplifier. Sense resistor RS1 sets the maximum
allowable source current. Once the input current limit is
reached, the charge current is decreased linearly until
the input current is below the desired threshold.
Duty cycle affects the accuracy of the input current
limit. AC load current also affects accuracy (see
Typical Operating Characteristics
). Refer to the
MAX1909 EV kit data sheet for more details on reduc-
ing the effects of switching noise.
When choosing the current-sense resistor RS1, careful-
ly calculate its power rating. Take into account varia-
tions in the system
’
s load current and the overall
accuracy of the sense amplifier. Note that the voltage
drop across RS1 contributes additional power loss,
which reduces efficiency.
System currents normally fluctuate as portions of the
system are powered up or put to sleep. Without input
current regulation, the input source must be able to
deliver the maximum system current and the maximum
charger input current. By using the input current-limit
circuit, the output current capability of the AC wall
adapter can be lowered, reducing system cost.
Current Measurement
The MAX1909 includes an input current monitor IINP.
The current delivered at the IINP output is a scaled-
down replica of the system load current plus the input-
referred charge current that is sensed across CSSP
and CSSN inputs. The output voltage range is 0 to 3V.
The voltage of IINP is proportional to the output current
according to the following equation:
V
IINP
= I
SOURCE
R
S1
G
IINP
R
9
where I
SOURCE
is the DC current supplied by the AC
adapter power, G
IINP
is the transconductance of IINP
(3mA/V typ), and R9 is the resistor connected between
IINP and ground.
Leave the IINP pin unconnected if not used.
LDO Regulator
LDO provides a 5.4V supply derived from DCIN and
can deliver up to 10mA of extra load current. The low-
side MOSFET driver is powered by DLOV, which must
be connected to LDO as shown in Figure 1. LDO also
supplies the 4.2235V reference (REF) and most of the
control circuitry. Bypass LDO with a 1μF capacitor.
Shutdown and Charge Inhibit (
PKPRES
)
When the AC adapter is removed, the MAX1909 shuts
down to a low-power state that does not significantly
load the battery. Under these conditions, a maximum of
6μA is drawn from the battery through the combined
load of the SRC, CSSP, CSSN, CSIP, CSIN, and BATT
inputs. The charger enters this low-power state when
DCIN falls below the undervoltage lockout (UVLO)
threshold of 7V. The PDS switch turns off, the PDL
switch turns on, and the system runs from the battery.
The body diode of the PDL switch prevents the voltage
on the power source output from collapsing.
Charging can also be inhibited by driving the pack
detection input (
PKPRES
) high, which suspends switch-
ing and pulls CCI, CCS, and CCV to ground. The PDS
and PDL drivers, LDO, input current monitor, and con-
trol logic (ACOK) all remain active in this state.
Approximately 3mA of supply current is drawn from the
AC adapter and 3μA (max) is drawn from the battery to
support these functions. The threshold voltage of
PKPRES
is 90% of V
LDO
(typ), with hysteresis of 1%
V
LDO
to prevent erratic transitions.
In smart-battery systems,
PKPRES
is usually driven
from a voltage-divider formed with a low-value resistor
or PTC thermistor inside the battery back and a local
resistive pullup. This arrangement automatically detects
the presence of a battery. A PTC thermistor can be
used to shut down the MAX1909 when the battery pack
is hot (see the
Thermal Charge Qualification
section).
I
RS
V
V
IN
CLS
REF
=
×
0 075
.
1
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1909ETI+ | 功能描述:电池管理 Multichemistry Battery Chargers RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX1909ETI+T | 功能描述:电池管理 Multichemistry Battery Chargers RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX1909ETI-T | 功能描述:电池管理 RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX1909EVKIT | 功能描述:电池管理 Evaluation Kit for the MAX1909 RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX190ACNG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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