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| 型号： | MAX8903YETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/30页 |
| 文件大小： | 0K |
| 描述： | IC DC/DC CHARGER LI+ 2A 28-TQFN |
| 产品培训模块： | Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | Smart Power Selector™ |
| 功能： | 充电管理 |
| 电池化学： | 锂离子（Li-Ion）、锂聚合物（Li-Pol） |
| 电源电压： | 4.1 V ~ 16 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
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MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
Table 1. External Components List for Figures 2 and 3
COMPONENT
(FIGURES 2 AND 3)
C DC , C USB
C VL
C SYS
C BAT
C CT
R PU (X4)
THM
R T
FUNCTION
Input filter capacitor
VL filter capacitor
SYS output bypass capacitor
Battery bypass capacitor
Charger timing capacitor
Logic output pullup resistors
Negative TC thermistor
THM pullup resistor
PART
4.7μF ceramic capacitor
1.0μF ceramic capacitor
10μF (MAX8903A/MAX8903C/MAX8903D/MAX8903H/MAX8903J) or
22μF (MAX8903B/MAX8903E/MAX8903G/MAX8903Y) ceramic capacitor
10μF ceramic capacitor
0.15μF low TC ceramic capacitor
100k ?
Philips NTC thermistor, P/N 2322-640-63103, 0k ? ±5% at +25°C
10k ?
R IDC
R ISET
DC input current-limit programming resistor 3k ? ±1%, for 2A limit
Fast-charge current programming resistor 1.2k ? ±1%, for 1A charging
L1
DC input step-down inductor
1μH inductor with I SAT > 2A
die temperature. The feedback signal requiring the
smallest current controls the average output current in
the inductor. This scheme minimizes total power dissi-
pation for battery charging and allows the battery to
absorb any load transients with minimum system volt-
age disturbance.
If the battery voltage is below V SYSMIN , the charger does
not directly connect the system voltage to the battery
and the system voltage (V SYS ) is slightly above V SYSMIN
as shown in Figure 4. The battery charger independently
controls the battery charging current. V SYSMIN is set to
either 3.0V or 3.4V based on the version of MAX8903_.
See Table 6.
After the battery charges to 50mV above V SYSMIN , the
system voltage is connected to the battery. The battery
fast-charge current then controls the step-down con-
verter to set the average inductor current so that both
the programmed input current limit and fast-charge cur-
rent limit are satisfied.
DC-DC Step-Down Control Scheme
A proprietary hysteretic current PWM control scheme
ensures fast switching and physically tiny external com-
ponents. The feedback control signal that requires the
smallest input current controls the center of the peak
and valley currents in the inductor. The ripple current is
internally set to provide 4MHz operation. When the
input voltage decreases near the output voltage, very
high duty cycle occurs and, due to minimum off-time,
4MHz operation is not achievable. The controller then
provides minimum off-time, peak current regulation.
Similarly, when the input voltage is too high to allow
4MHz operation due to the minimum on-time, the con-
16
troller becomes a minimum on-time, valley current regu-
lator. In this way, ripple current in the inductor is always
as small as possible to reduce ripple voltage on SYS for
a given capacitance. The ripple current is made to vary
with input voltage and output voltage in a way that
reduces frequency variation. However, the frequency
still varies somewhat with operating conditions. See the
Typical Operating Characteristics.
DC Mode (DCM)
As shown in Table 2, the DC input supports both AC
adapters (up to 2A) and USB (up to 500mA). With the
DCM logic input set high, the DC input is in adapter
mode and the DC input current limit is set by the resis-
tance from IDC to GND (R IDC ). Calculate R IDC accord-
ing to the following equation:
R IDC = 6000V/I DC-MAX
With the DCM logic input set low, the DC input current
limit is internally programmed to 500mA or 100mA as
set by the IUSB logic input. With the IUSB logic input
set high, the DC input current limit is 500mA and the
DC input delivers current to SYS through the step-down
regulator. With the IUSB logic input set low, the DC
input current limit is 100mA. In this 100mA mode, the
step-down regulator is turned off and its high-side
switch operates as a linear regulator with a 100mA cur-
rent limit. The linear regulator’s output is connected to
LX and its output current flows through the inductor into
CS and finally to SYS.
The DCM pin has an internal diode to DC as shown in
Figure 1. To prevent current from flowing from DCM
through the internal diode and to the DC input, DCM
cannot be driven to a voltage higher than DC. The
Maxim Integrated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8904AETN+ | 功能描述:PMIC 解决方案 Point of Sales PMIC RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8904AETN+T | 功能描述:PMIC 解决方案 Point of Sales PMIC RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8904ETN+ | 功能描述:PMIC 解决方案 PMIC for 2-cell Li+ handheld RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8904ETN+T | 功能描述:PMIC 解决方案 PMIC for 2-cell Li+ handheld RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8904EVKIT+ | 制造商:Maxim Integrated Products 功能描述:EVALUATION KIT FOR MAX8904 - Boxed Product (Development Kits) |
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