参数资料
| 型号： | ISL6421ERZ |
| 厂商： | Intersil |
| 文件页数： | 6/18页 |
| 文件大小： | 0K |
| 描述： | IC REG SGL LNB CONTROL 32-QFN |
| 标准包装： | 60 |
| 应用： | 转换器，卫星信号接收机顶盒设计 |
| 输入电压： | 8 V ~ 14 V |
| 输出数： | 1 |
| 输出电压： | 13 V ~ 18 V |
| 工作温度： | -20°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-VFQFN 裸露焊盘 |
| 供应商设备封装： | 32-QFN（5x5） |
| 包装： | 管件 |
Application Note 1083
D1
Component Selection Guidelines
ISL6421/ISL6425
(LLC = HIGH)
STPS2L40U
C D
C LOAD
LNB
The ISL6421EVAL1A/ISL6425EVAL2 application schematics
show the configuration for a single LNB power supply.
TCAP Capacitor
A capacitor connected to the TCAP pin sets the transition
time from 13V to 18V. A 1μF minimum capacitor is
recommended for smooth transition with reduced peak
X DEVICE
currents. Figure 14 shows the transition time versus
capacitor value.
FIGURE 12. DC BACK-BIAS PROTECTION CIRCUIT FOR
ZERO LOAD CONDITION
During the tone fall time, the capacitors are essentially in
series so the charge will try to equally distribute between C D
and C LOAD . C LOAD will discharge allowing current to flow to
C D to match the falling voltage at the anode of the diode.
You will have to choose a capacitor, C D , that is large enough
to absorb the C LOAD discharging current and to minimize
the voltage drop created during the minimum tone fall time
specification, 5μs. A good choice would be to use a
capacitor for C D that is 40 times the value of C LOAD .
Figure 13 shows the tone mode operation at the cathode of
3.8
3.3
2.8
2.3
1.8
1.3
0.8
the protection diode in a zero load condition and the
charging current between C D and C LOAD . Large current
transients may occur from a fast dV/dt created if a DC supply
were connected to the output of the ISL6421/ISL6425,
therefore, to use the circuit in Figure 13, the DC supply
0.3
0.15 0.65 1.15 1.65
TCAP (μF)
FIGURE 14. TCAP CAPACITOR VALUE vs OUTPUT
TRANSITION TIME
2.15
would have to be limited to 1A maximum current during the
dV/dt voltage transient to fully protect the IC.
I CLOAD 20mA/DIV
The programmable output voltage rise and fall times can be
set by an external capacitor. The output rise and fall times
will be approximately 3400 times the TCAP value. For the
recommended range of 0.47 μ F to 2.2 μ F, the rise and fall
time would be 1.6ms to 7.6ms. Use of a 0.47 μ F capacitor
insures the PWM will stay below its overcurrent threshold
when charging a 120 μ F VSW filter cap during the worst case
13V to 19V transition. This feature only affects the turn-on
and programmed voltage rise and fall times. Figure 15
shows the 13V to 18V transition with TCAP = 1μF.
VOUT 2V/DIV
VO1 200mV/DIV
FIGURE 13. ZERO LOAD 22kHz TONE AT CATHODE OF
DIODE AND DRIVING CURRENT CHARGING AND
DISCHARGING C LOAD
5ms/DIV
FIGURE 15. 13V TO 18V TRANSITION
6
AN1083.1
May 6, 2005
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相关代理商/技术参数 |
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| ISL6421ERZ-T | 功能描述:电流型 PWM 控制器 SINGLE LNBP SUPPLY CONTROL VG 32LD MLFP 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 |
| ISL6421EVAL1 | 功能描述:EVALUATION BOARD 1 ISL6421 RoHS:否 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL6422BERZ | 功能描述:直流/直流开关转换器 DL LNB SUPPLY + CONT VAGEG W/I2C RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| ISL6422BERZ-T | 功能描述:直流/直流开关转换器 DL LNB SUPPLY + CONT VAGEG W/I2C RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| ISL6422BEVEZ | 功能描述:直流/直流开关转换器 DL LNB SUPPLY + CONT VAGEG W/I2C RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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