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参数资料
| 型号： | MAX1846EUB+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 12/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR FLYBK INV CM 10UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 345kHz |
| 占空比： | 98% |
| 电源电压： | 3 V ~ 16.5 V |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 是 |
| 反相： | 是 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
High-Efficiency, Current-Mode,
Inverting PWM Controller
V IN
+12V
12.2 μ H
12 μ F VP1-0190
25V
1:4
0.47 μ F
8
16
2 1
VL POL
SHDN
SYNC
15
IN
EXT
CS
14
13
IRLL2705
CMR1U-02
470 ?
100pF
100V
V OUT
-48V AT 100mA
12 μ F
100V
0.033 μ F
270k ?
4
3
MAX1847
COMP
FREQ
N.C.
PGND
7, 9
12
0.05 ?
0.5W
383k ?
1%
150k ?
5
REF
FB
GND
10, 11
6
1800pF
10.0k ?
1%
0.1 μ F
Figure 1. Using an N-Channel MOSFET (MAX1847 only)
Calculate the Duty Cycle
The duty cycle is the ratio of the on-time of the MOSFET
switch to the oscillator period. It is determined by the
ratio of the input voltage to the output voltage. Since
the input voltage typically has a range of operation, a
minimum (D MIN ) and maximum (D MAX ) duty cycle is
calculated by:
1.25V and the regulation voltage for FB is nominally 0.
The load presented to the reference by the feedback
resistors must be less than 500μA to guarantee that
V REF is in regulation (see Electrical Characteristics
Table). Conversely, the current through the feedback
resistors must be large enough so that the leakage cur-
rent of the FB input (50nA) is insignificant. Therefore,
D MIN =
D MAX =
? V OUT + V D
V IN ( MAX ) ? V SW ? V LIM ? V OUT + V D
? V OUT + V D
V IN ( MIN ) ? V SW ? V LIM ? V OUT + V D
select R2 so that I R2 is between 50μA and 250μA.
I R2 = V REF / R2
where V REF = 1.25V. A typical value for R2 is 10k ? .
Once R2 is selected, calculate R1 with the following
equation:
R1 = R2 x (-V OUT / V REF )
where V D is the forward drop across the output diode,
V SW is the drop across the external FET when on, and
V LIM is the current-limit threshold. To begin with,
assume V D = 0.5V for a Schottky diode, V SW = 100mV,
and V LIM = 100mV. Remember that V OUT is negative
when using this formula.
Setting the Output Voltage
The output voltage is set using two external resistors to
form a resistive-divider to FB between the output and
REF (refer to R1 and R2 in Figure 1). V REF is nominally
Setting the Operating Frequency
The MAX1846/MAX1847 are capable of operating at
switching frequencies from 100kHz to 500kHz. Choice
of operating frequency depends on a number of fac-
tors:
1) Noise considerations may dictate setting (or syn-
chronizing) f OSC above or below a certain fre-
quency or band of frequencies, particularly in RF
applications.
12
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相关代理商/技术参数 |
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| MAX1846EVKIT | 功能描述:电流型 PWM 控制器 Evaluation Kit for the MAX1846 MAX1847 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX1847EEE | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX1847EEE+ | 功能描述:电流型 PWM 控制器 Current-Mode Invert PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX1847EEE+ | 制造商:Maxim Integrated Products 功能描述:PWM CONTROLLER ((NW)) |
| MAX1847EEE+T | 功能描述:电流型 PWM 控制器 Current-Mode Invert PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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