参数资料
| 型号： | A4447SLJTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 6/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 2A 8SOIC |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 24 V |
| 输入电压： | 8 V ~ 50 V |
| PWM 型： | 电流模式 |
| 电流 - 输出： | 2A |
| 同步整流器： | 无 |
| 工作温度： | -20°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm Width）裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 8-SOIC-EP |
| 产品目录页面： | 1141 (CN2011-ZH PDF) |
| 其它名称： | 620-1329-6 |
A4447
High Voltage Step Down Regulator
Component Selection
L1. The inductor must be rated to handle the total load current.
The value should be chosen to keep the ripple current to a reason-
able value. The ripple current, I RIPPLE , can be calculated by:
Substituting into equation 7:
f SW = 1 / (7 μ s +1.12 μ s) = 123 kHz
I RIPPLE = V L(OFF) × t OFF / L
V L(OFF) = V OUT + V f + I L(AV) × R L
(3)
(4)
Higher inductor values can be chosen to lower the ripple cur-
rent. This may be an option if it is required to increase the total
maximum current available above that drawn from the switching
Example:
Given V OUT = 5 V, V f = 0.55 V, V IN = 42 V, I LOAD = 0.5 A, power
inductor with L = 180 μ H and R L = 0.5 Ω Rdc at 55°C, t OFF =
7 μ s, and R DS(on) = 1 Ω .
Substituting into equation 4:
V L(OFF) = 5 V + 0.55 V+ 0.5 A × 0.5 Ω = 5.8 V
Substituting into equation 3:
I RIPPLE = 5.8 V × 7 μ s / 180 μ H = 225 mA
The switching frequency, f SW , can then be estimated by:
regulator. The maximum total current available, I LOAD(MAX) , is:
I LOAD(MAX) = I CL (min) – I RIPPLE / 2 (8)
where I CL (min) is 2.2 A, from the Electrical Characteristics table.
D1. The Schottky catch diode should be rated to handle 1.2 times
the maximum load current. The voltage rating should be higher
than the maximum input voltage expected during all operating
conditions. The duty cycle for high input voltages can be very
close to 100%.
COUT. The main consideration in selecting an output capacitor
f SW = 1 / ( t ON + t OFF )
t ON = I RIPPLE × L / V L(ON)
V L(ON) = V IN – I L(AV) × R DS(on) – I L(AV) × R L – V OUT
Substituting into equation 7:
(5)
(6)
(7)
is voltage ripple on the output. For electrolytic output capacitors,
a low-ESR type is recommended.
The peak-to-peak output voltage ripple is simply I RIPPLE ×
ESR. Note that increasing the inductor value can decrease the
ripple current. The minimum voltage rating of the capacitor is
V L(ON) = 42 V – 0.5 A × 1 Ω – 0.5 A × 0.5 Ω – 5 V = 36 V
Substituting into equation 6:
t ON = 225 mA × 180 μ H / 36 V = 1.12 μ s
10 V. However, because ESR decreases with voltage, the most
cost-effective choice may be rated higher in voltage. It is recom-
mended that the ESR be less than 100 m Ω .
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
相关PDF资料 |
PDF描述 |
|---|---|
| A4490EES-T | IC REG BUCK ADJ 1.5A TRPL 20QFN |
| A4491EESTR-T | IC REG BUCK ADJ 2.2A TRPL 20QFN |
| A4931MET-T | IC DC MOTOR PREDRIVER 3PH 28QFN |
| A4934GLPTR-T | IC BLDC DVR 3PHASE 16-ETSSOP |
| A4936METTR-T | IC DC MOTOR PREDRIVER 3PH 32QFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| A4448RT | 制造商:Pentair Technical Products / Hoffman 功能描述:Wiring Trough 4.00x4.00x48.00 , 4.00x4.00x48.00, Steel |
| A-4448RT | 制造商:Pentair Technical Products / Hoffman 功能描述:Wiring Trough 4.00x4.00x48.00 |
| A4448T1T | 制造商:Pentair Technical Products / Hoffman 功能描述:4X4, 48 LONG TYPE 1 TROUGH Gray, 4.00x4.00x48.00, Steel |
| A445 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:DISPLAY 0-20 OR 24MA |
| A4450KESTR-J | 功能描述:Buck-Boost Regulator Positive Output Step-Up/Step-Down DC-DC Controller IC 20-QFN (4x4) 制造商:allegro microsystems, llc 系列:汽车级，AEC-Q100 包装:剪切带（CT） 零件状态:新产品 输出类型:晶体管驱动器 功能:升压/降压 输出配置:正 拓扑:降压-升压 输出数:1 输出阶段:1 电压 - 电源（Vcc/Vdd）:3 V ~ 36 V 频率 - 开关:250kHz ~ 2.2MHz 占空比（最大）:- 同步整流器:无 时钟同步:是 串行接口:- 控制特性:使能，频率控制，软启动 工作温度:-40°C ~ 150°C（TJ） 封装/外壳:20-WFQFN 裸露焊盘 供应商器件封装:20-QFN（4x4） 标准包装:1 |
发布紧急采购，3分钟左右您将得到回复。