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| 型号： | MAX1772EEI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 15/20页 |
| 文件大小： | 0K |
| 描述： | IC BAT CHRG BUILD BLCK 28QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 功能： | 充电管理 |
| 电池化学： | 多化学 |
| 电源电压： | 8 V ~ 28 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 28-QSOP |
| 包装： | 带卷 (TR) |
Low-Cost, Multichemistry Battery-
Charger Building Block
Table 1. Cell-Count Programming Table
Use IINP to monitor the system input current being
sensed across CSSP and CSSN. The output voltage
CELL
V CELLS < 0.20V
CELL COUNT
2
range is 0 to 3V. The voltage of IINP is proportional to
the output current by the equation:
0.40V < V CELLS < V LDO -0.5V
V LDO - 0.25V < V CELLS < V LDO
3
4
V IINP = I SOURCE × RS 1 × G IINP × R 10
( 6 )
where I SOURCE is the DC current being supplied by the
The input source current is the sum of the device cur-
rent, the charger input current, and the load current.
The device current is minimal (6mA) in comparison to
the charge and load currents. The actual source cur-
rent required is determined as follows:
AC adapter power, G IINP is the transconductance of
IINP (1μS typ), and R10 is the resistor connected
between IINP and ground.
In the typical application circuit, duty cycle affects the
accuracy of V IINP (Figure 3). AC load current also
I SOURCE LOAD + [ ( I CHARGE BATT ) / ( V IN × η ) ]
= I × V
( 3 )
affects accuracy (Figure 4).
Connect IINP pin to ground if it is not used.
where η is the efficiency of the DC-DC converter (85%
to 95% typ).
V CLS determines the reference voltage of the GMS
error amplifier. Sense resistor RS1 sets the maximum
allowable source current. Calculate the maximum cur-
rent as follows:
I SOURCE_MAX = V CLS / ( 20 × RS 1 ) ( 4 )
Once the input current limit is reached, the charging
current is tapered back until the input current is below
the desired threshold.
When choosing the current-sense resistor, note that the
voltage drop across this resistor causes further power
loss, reducing efficiency.
AC Adapter Detection
Connect the AC adapter voltage through a resistive
divider to ACIN to detect when AC power is available,
as shown in Figure 1. ACOK is an open-drain output
and is high when ACIN is less than REF/2.
Current Measurement
Use ICHG to monitor the battery-charging current
being sensed across CSIP and CSIN. The output volt-
age range is 0 to 3V. The voltage of ICHG is proportion-
al to the output current by the equation:
LDO Regulator
LDO provides a 5.4V supply derived from DCIN and
can deliver up to 15mA of current. The MOSFET drivers
are powered by DLOV and BST, which must be con-
nected to LDO as shown in Figure 1. LDO also supplies
the 4.096V reference (REF) and most of the control cir-
cuitry. Bypass LDO with a 1μF capacitor.
DC-to-DC Converter
The MAX1772 employs a buck regulator with a boot-
strapped NMOS high-side switch and a low-side NMOS
synchronous rectifier.
DC-DC Controller
The control scheme is a constant off-time variable fre-
quency, cycle-by-cycle current mode. The off-time is
constant for a given BATT voltage. It varies with V BATT
operation; a maximum on-time of 10ms allows the con-
troller to achieve >99% duty cycle with continuous con-
duction. Figure 5 shows the controller functional
diagram.
MOSFET Drivers
The low-side driver output DLO swings from 0 to DLOV.
DLOV is usually connected through a filter to LDO. The
high-side driver output DHI is bootstrapped off LX and
swings from V LX to V BST . When the low-side driver
turns on, BST rises to one diode voltage below DLOV.
Filter DLOV with a resistor-capacitor (RC) circuit whose
V ICHG = I ICHG × RS 2 × G ICHG × R 9
( 5 )
cutoff frequency is about 50kHz. The configuration in
Figure 1 introduces a cutoff frequency of around
48kHz:
where I ICHG is the battery-charging current, G ICHG is
the transconductance of ICHG (1mS typ), and R9 is the
resistor connected between ICHG and ground.
Connect ICHG pin to ground if it is not used.
f = 1/2 π RC = 1 / (2 π 33 Ω 0.1μF) = 48kHz
(7)
______________________________________________________________________________________
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相关代理商/技术参数 |
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| MAX1772EEI-TG074 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1772EVKIT | 功能描述:电池管理 MAX1772EVKIT 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 |
| MAX1773AEUP | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX1773AEUP+ | 功能描述:电池管理 Power Source Selector for Dual-Battery Systems 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 |
| MAX1773AEUP+T | 功能描述:电池管理 Power Source Selector for Dual-Battery Systems 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 |
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