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| 型号： | MAX1678EUA+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 10/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BOOST SYNC 3.3V/ADJ 8UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 升压（升压） |
| 输出类型： | 两者兼有 |
| 输出数： | 1 |
| 输出电压： | 3.3V，2 V ~ 5.5 V |
| 输入电压： | 0.7 V ~ 5.5 V |
| 电流 - 输出： | 90mA |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-TSSOP，8-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-uMAX |
1-Cell to 2-Cell, Low-Noise,
High-Efficiency, Step-Up DC-DC Converter
Applications Information
Output Voltage Selection
I OUT ( MAX ) = M x
1
2
x
K
L
x
V BATT
V OUT
The MAX1678 operates with a fixed 3.3V or adjustable
output. To select fixed-voltage operation, connect FB to
GND (Figure 7). For an adjustable output between 2V
and 5.5V, connect FB to a resistor voltage-divider
between OUT and GND (Figure 8). FB regulates to
1.23V.
Since FB leakage is 10nA max, select feedback resistor
R2 in the 100k ? to 1M ? range. R1 is given by:
where M is an empirical factor that takes into account
losses in the MAX1678 internal switches and in the
inductor resistance. K is the V-μs factor that governs
the inductor charge time. Nominally, M = 0.9 and
K = 8V-μs. M should be further reduced by 0.1 for each
ohm of inductor resistance.
The inductor’s saturation-current rating must exceed
the worst-case peak current limit set by the MAX1678’s
R1 = R2 x ? OUT ? 1 ?
? V ?
? V REF ?
timing algorithm:
I PEAK =
K MAX
L
where V REF = 1.23V.
Maximum Output Current
and Inductor Selection
The MAX1678 is designed to work well with a 47μH
inductor in most low-power applications. 47μH is a suf-
ficiently low value to allow the use of a small surface-
mount coil, but large enough to maintain low ripple. The
Typical Operating Characteristics section shows perfor-
mance curves with several 47μH and 22μH coils. Low
where K MAX = 11.2V-μs. It is usually acceptable to
exceed most coil saturation-current ratings by 20% with
no ill effects; however, the maximum recommended I PEAK
for the MAX1678 internal switches is 550mA, so inductor
values below 22μH are not recommended. For optimum
efficiency, inductor series resistance should be less than
150mV/I PEAK . Table 1 lists suggested inductors and sup-
pliers.
Table 1. Suggested Inductors and Suppliers
inductance values supply higher output current but
also increase ripple and reduce efficiency. Note that
values below 22μH are not recommended due to
MAX1678 switch limitations. Higher inductor values
reduce peak inductor current (and consequent ripple
and noise) and improve efficiency, but also limit output
current.
The relationship between current and inductor value is
approximately:
PIN
Coilcraft
Murata
Sumida
TDK
INDUCTOR
DS1608C-223,
DS1608C-473
LQH4N470K,
LQH3C470K
CD43-220,
CD43-470
NLC453232T-220K,
NLC453232T-470K
PHONE
(847) 639-6400
(814) 237-1431
(847) 956-0666
(847) 390-4373
INPUT
0.87V TO V OUT
L1
47 μ H, 200mA
INPUT
0.87V TO V OUT
L1
47 μ H
C1
10 μ F
R3
BATT
LX
C1
10 μ F
R3
BATT
PFI
LX
OUT
V OUT = 2V
TO 5.5V
OUT
PFI
OUT
3.3V OUT
OUT
R4
R5
MAX1678
C2
10 μ F
R4
R5
MAX1678
R1
C2
PFO
SHDN
GND
FB
PFO
SHDN
GND
FB
R2
Figure 7. 3.3V Standard Application Circuit
Figure 8. Adjustable Output Circuit
10
______________________________________________________________________________________
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相关代理商/技术参数 |
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| MAX1678EVKIT | 功能描述:电源管理IC开发工具 Evaluation Kit for the MAX1678 RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX1679EUA | 功能描述:电池管理 Battery Charger Current-Limited Sply 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 |
| MAX1679EUA+ | 功能描述:电池管理 Battery Charger Current-Limited Sply 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 |
| MAX1679EUA+T | 功能描述:电池管理 Battery Charger Current-Limited Sply 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 |
| MAX1679EUA-T | 功能描述:电池管理 Battery Charger Current-Limited Sply 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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