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参数资料
| 型号： | DS2148TN |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Digital Transmission Interface |
| 英文描述： | DATACOM, PCM TRANSCEIVER, PQFP44 |
| 封装： | TQFP-44 |
| 文件页数： | 4/16页 |
| 文件大小： | 603K |
| 代理商： | DS2148TN |
MAX8625A
High-Efficiency, Seamless Transition,
Step-Up/Down DC-DC Converter
12
______________________________________________________________________________________
Applications Information
Selecting the Output Voltage
The MAX8625A output is nominally fixed at 3.3V.
Connect FB to GND to select the internally fixed-output
voltage. For an adjustable output voltage, connect FB
to the center tap of an external resistor-divider connect-
ed from the output to GND (R1 and R2 in Figure 3).
Select 100k
for R2 and calculate R1 using the follow-
ing equation:
where VFB = 1.25V and VOUT is the desired output reg-
ulation voltage. VOUT must be between 1.25V and 4V.
Note that the minimum output voltage is limited by the
minimum duty cycle. VOUT cannot be below 1.25V.
Calculating Maximum Output Current
The maximum output current provided by the MAX8625A
circuit depends on the inductor value, switching frequen-
cy, efficiency, and input/output voltage.
See the
Typical Operating Characteristics section for
the Maximum Load Current vs. Input Voltage graph.
Capacitor Selection
The input and output ripple currents are both discontin-
uous in this topology. Therefore, select at least two
22F ceramic capacitors at the input. Select two 22F
ceramic output capacitors. For best stability over a
wide temperature range, use X5R or better dielectric.
Inductor Selection
The recommended inductance range for the
MAX8625A is 3.3H to 4.7H. Larger values of L give a
smaller ripple, while smaller L values provide a better
transient response. This is because, for boost and step-
up/down topologies, the crossover frequency is
inversely proportional to the value of L for a given load
and input voltage. The MAX8625A is internally compen-
sated, and therefore, the choice of power components
for stable operation is bounded. A 3.3H inductor with
2A rating is recommended for the 3.3V fixed output with
0.8A load.
PCB Layout and Routing
Good PCB layout is important to achieve optimal per-
formance from the MAX8625A. Poor design can cause
excessive conducted and/or radiated noise.
Conductors carrying discontinuous currents and any
high-current path should be made as short and wide as
possible. Keep the feedback network (R1 and R2) very
close to the IC, preferably within 0.2 inches of the FB
and GND pins. Nodes with high dv/dt (switching
nodes) should be kept as small as possible and routed
away from FB. Connect the input and output capacitors
as close as possible to the IC. Refer to the MAX8625A
evaluation kit for a PCB layout example.
Rk
V
OUT
FB
1
100
1
=×
Figure 3. Typical Application Circuit (Adjustable Output)
U1
MAX8625A
R2
100k
R1
140k
IN
SKIP
IN
OUT
FB
OUT
LX1
LX2
12
13
14
6
ON
5
REF
8
34
L
3.3
H
C1, C2
22
F
C5
0.1
F
9
7
10
C3, C4
22
F
INPUT
2.7V TO 5.5V
MODE
SELECTION
INPUT
OUTPUT
3V
OFF
ON
GND
11
12
相关PDF资料 |
PDF描述 |
|---|---|
| DS2148T | DATACOM, PCM TRANSCEIVER, PQFP44 |
| DS2151QNB | DATACOM, FRAMER, PQCC44 |
| DS2151QB | DATACOM, FRAMER, PQCC44 |
| DS2152LN | DATACOM, FRAMER, PQFP100 |
| DS2152L | DATACOM, FRAMER, PQFP100 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS2148TN+ | 功能描述:网络控制器与处理器 IC 5V E1/T1/J1 Line Interface RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| DS2148TNB | 功能描述:网络控制器与处理器 IC RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| DS2148TNC | 功能描述:网络控制器与处理器 IC RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| DS2148TN-W | 功能描述:网络控制器与处理器 IC RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| DS2149 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:5V T1/J1 Line Interface Unit |
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