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| 型号： | MAX8903NETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 23/30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
on-time constraints (t ONMIN ), the regulator becomes a
fixed minimum on-time valley current regulator.
Versions of the MAX8903 with f SW = 4MHz offer the
(4) L OUT _ MIN _ t ON
=
( V DC(MAX ) ? V SYS(MIN) ) × t ON
K × I SDLIM
smallest LOUT while delivering good efficiency with low
input voltages (5V or 9V). For applications that use high
input voltages (12V), the MAX8903G with f SW = 1MHz
is the best choice because of its higher efficiency.
For a given maximum output voltage, the minimum
where V DC(MAX) is maximum input voltage, V SYS(MIN) is
the minimum charger output voltage, and t ON is the on-
time at high input voltage, as given by the following
equation:
t ON = t ONMIN if ?
?
V SYS ( MIN )
× ? ≤ t ONMIN ,
inductor ripple current condition occurs at the lowest
input voltage that allows the regulator to maintain f SW
operation. If the minimum input voltage dictates an off-
time less than t OFFMIN , then the minimum inductor rip-
ple condition occurs just before the regulator enters
fixed minimum off-time operation. To allow the current-
mode regulator to provide a low-jitter, stable duty factor
(5)
otherwise,
t ON = ×
? V SYS ( MIN )
? V DC ( MAX )
V DC ( MAX )
1 ?
f SW ?
1
f SW
operation, the minimum inductor ripple current
(I L_RIPPLE_MIN ) should be greater than 150mA in the
minimum inductor ripple current condition. The maxi-
mum allowed output inductance L OUT_MAX is therefore
The saturation current DC rating of the inductor (I SAT )
must be greater than the DC step-down output current
limit (I SDLIM ) plus one-half the maximum ripple current,
as given by equation (6).
?
V SYS ( MAX ) ?
= t
? ×
≤ t OFFMIN ,
?
V DC ( MIN ) ?
t OFF OFFMIN if ? 1 ?
obtained using the equations (1) and (2) below.
(1)
1
f SW
(6)
I SAT > I SDLIM +
IL RIPPLE _ MAX
2
otherwise,
where IL RIPPLE_MAX is the greater of the ripple currents
obtained from (7) and (8).
t OFF = ? 1 ?
?×
?
?
V SYS ( MAX ) ?
V DC ( MIN ) ?
1
f SW
(7)
IL RIPPLE _ MIN _ T OFF =
V SYS ( MAX ) × t OFF
L OUT
where t OFF is the off-time, V SYS(MAX) is maximum charger
output voltage, and V DC(MIN) is minimum DC input volt-
age.
(8)
IL RIPPLE _ MIN _ T ON =
( V DC(MAX ) ? V SYS(MIN) ) × t ON
L O U T
(2)
L OUT _ MAX =
V SYS ( MAX ) × t OFF
I L _ RIPPLE _ MIN
PCB Layout and Routing
Good design minimizes ground bounce and voltage gra-
where L OUT_MAX is the maximum allowed inductance.
To obtain a small-sized inductor with acceptable core
loss, while providing stable, jitter-free operation at the
advertised f SW , the actual output inductance (L OUT ), is
obtained by choosing an appropriate ripple factor K, and
picking an available inductor in the range inductance
yielded by equations (2), (3), and (4). L OUT should also
not be lower than the minimum allowable inductance as
shown in Table 6. The recommended ripple factor ranges
from (0.2 ≤ K ≤ 0.45) for (2A ≥ I SDLIM ≥ 1A) designs.
dients in the ground plane, which can result in instability
or regulation errors. The GND and PGs should connect to
the power-ground plane at only one point to minimize the
effects of power-ground currents. Battery ground should
connect directly to the power-ground plane. The ISET
and IDC current-setting resistors should connect directly
to GND to avoid current errors. Connect GND to the
exposed pad directly under the IC. Use multiple tightly
spaced vias to the ground plane under the exposed pad
to help cool the IC. Position input capacitors from DC,
SYS, BAT, and USB to the power-ground plane as close
(3)
L OUT _ MIN _ T OFF =
V SYS ( MAX ) × t OFF
K × I SDLIM
as possible to the IC. Keep high current traces such as
those to DC, SYS, and BAT as short and wide as possi-
ble. Refer to the MAX8903A Evaluation Kit for a suitable
PCB layout example.
where t OFF is the minimum off-time obtained from (1).
Maxim Integrated
23
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8903YETI+ | 功能描述:电池管理 Dual AC/USB Powered 1-Cell Li+ Charger 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 |
| MAX8903YETI+C67 | 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 |
| MAX8903YETI+T | 功能描述:电池管理 Dual AC/USB Powered 1-Cell Li+ Charger 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 |
| MAX8903YETI+TW | 功能描述:电池管理 2A 1-Cell Li+ DC-DC Charger for USB and Adapter Power 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 |
| MAX8903YETI+W | 功能描述:电池管理 2A 1-Cell Li+ DC-DC Charger for USB and Adapter Power 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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