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| 型号： | A4401KL-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 6/17页 |
| 文件大小： | 0K |
| 描述： | IC QUASI FLYBACK CONVERTER 8SOIC |
| 标准包装： | 98 |
| 显示器类型： | 真空荧光 (VF) |
| 电流 - 电源： | 2.3mA |
| 电源电压： | 7 V ~ 40 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 管件 |
A4401
Automotive Quasi-Resonant Flyback Control IC
In the event of an overload, the current demand signal
produced by the Gm amplifier restricts the output cur-
rent by introducing pulse-by-pulse current limiting.
Regulation Voltage
To determine the sense resistor value, assume that the
minimum sense voltage before current limiting occurs
is 600 mV. A reasonable maximum voltage to select
during normal operation would be 500 mV. Then, the
resistor value can be found as follows:
The feedback resistors, R5 and R6, determine the
voltage of the output rail to which they are connected,
R SENSE =
500 mV
I PK
.
(4)
V REF ×(R5 + R6)
V OUT =
I RMS = I PK × ? ?
?
?
according to the following formula:
,
R6
where R6 should be approximately 5 k Ω .
The internal 1.2 V reference has a ±2% worst case
(1)
The power losses in the resistor can be found by first
determining the rms current through it:
? D (max) ? ?
.
3 (5)
Then, the losses in sense resistor are:
tolerance, plus there is an input bias current, I BIAS , on
the feedback node, VA, that has a small influence. This
P RDS = I 2 RMS × R SENSE .
(6)
P OUT (max)
I AV =
(2)
2 × I AV
I PK =
(3)
current flows into the ground referenced resistor, R6,
creating a small voltage offset.
In applications where the main control output (anode
or grid) can run at relatively light loads (relative to the
filament load), it may be necessary to “mix” the feed-
back signal. This involves adding an additional feed-
back from the filament output to the VA input. Note
that this only applies to DC filament outputs.
R3 Current Sense Resistor Selection
To determine the resistance value, the maximum peak
current needs to be determined. First determine the
average input current, I AV , as follows:
,
% × V IN (max)
where P OUT is the output power. Then, the peak cur-
rent through the sense resistor:
,
D (max)
where D is limited to 0.7, or can be precisely found as
described in the Magnetics Design section. Note that
a D of 0.7 is chosen in order to achieve 0 V switching
with a V BAT of 13.5 V.
The power rating of the resistor can be selected based
on the power dissipation. When selecting a resistor
it is worth noting that the maximum power rating
is valid up to 70°C and derates linearly to 0 W at a
temperature of typically between 120°C and 140°C.
Check the resistor manufacturer guidelines.
Note that is imperative that this resistor be a low
inductance type; avoid wire wound. Standard surface
mount devices are usually acceptable.
Soft Start
When power is initially applied, assuming the input
voltage turn-on threshold is reached, and the EN input
is enabled, the controller is initiated and the MOSFET,
Q1, is turned on for the first switching cycle. Initially,
while the output volts are rising towards the target reg-
ulation point set by the soft start circuit, the MOSFET
will run at current limit.
During a soft start cycle, the reference voltage is
ramped from 0 to 1.2 V in 32 steps over a period of 10
ms under the control of a DAC. This forces the output
of the amplifier to vary between 0.8 and 1.5 V, which
in turn reduces the effects of inrush current and volt-
age overshoot on the outputs.
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A4401KLTR-T | 功能描述:IC QUASI FLYBACK CONVERTER 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 显示器驱动器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 显示器类型:真空荧光 (VF) 配置:5 x 7（矩阵） 接口:串行 数字或字符:- 电流 - 电源:3.5mA 电源电压:2.7 V ~ 3.6 V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:16-SSOP（0.154"，3.90mm 宽） 供应商设备封装:16-QSOP 包装:带卷 (TR) |
| A4402 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Constant On-Time Buck Converter with Integrated Linear Regulator |
| A4402_1 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Constant On-Time Buck Converter with Integrated Linear Regulator |
| A4402_12 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:The A4402 is a dual-output regulator, combining in a single package a constant on-time buck regulator and a linear regulator (LDO)a??each with adjustable output voltages. |
| A4402ELPTR-T | 功能描述:IC REG DL BUCK/LINEAR 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
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