- 您现在的位置：买卖IC网 > PDF目录1776 > ADP1821ARQZ-R7 (Analog Devices Inc)IC REG CTRLR BUCK PWM VM 16-QSOP PDF资料下载
参数资料
| 型号： | ADP1821ARQZ-R7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 12/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 16-QSOP |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 720kHz |
| 占空比： | 90% |
| 电源电压： | 3.7 V ~ 5.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 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： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 产品目录页面： | 791 (CN2011-ZH PDF) |
| 其它名称： | ADP1821ARQZ-R7DKR |
ADP1821
APPLICATION INFORMATION
SELECTING THE INPUT CAPACITOR
Use the following equation to choose the inductor value:
The input current to a buck converter is a pulsed waveform. It is
zero when the high-side switch is off and approximately equal
L =
1
f SW × Δ I L
? V ?
V OUT ? 1 ? OUT ?
? V IN ?
(4)
D =
V OUT
?
?
? + ( 4 f SW ESL ) 2
ESR 2 + ? ?
(5)
Δ V OUT = Δ I L
to the load current when it is on. The input capacitor carries the
input ripple current, allowing the input power source to supply
only the dc current. The input capacitor needs sufficient ripple
current rating to handle the input ripple and the equivalent series
resistance (ESR) that is low enough to mitigate input voltage
ripple. For the usual current ranges for these converters, good
practice is to use two parallel capacitors placed close to the drains
of the high-side switch MOSFETs, one bulk capacitor of suffi-
ciently high current rating as calculated in Equation 1, along
with 10 μF of ceramic capacitor.
Select an input bulk capacitor based on its ripple current rating.
First, determine the duty cycle of the output with the larger load
current by
(1)
V IN
Second, determine the input capacitor ripple current, which is
approximately
where:
L is the inductor value.
f SW is the switching frequency.
V OUT is the output voltage.
V IN is the input voltage.
Δ I L is the inductor ripple current, typically 1/3 of the maximum
dc load current.
Choose the output bulk capacitor to set the desired output voltage
ripple. The impedance of the output capacitor at the switching
frequency multiplied by the ripple current gives the output
voltage ripple. The impedance is made up of the capacitive
impedance plus the nonideal parasitic characteristics, the ESR
and the equivalent series inductance (ESL). The output voltage
ripple can be approximated with
2
1
?
? 8 f SW C OUT ?
I RIPPLE ≈ I L D ( 1 ? D )
(2)
where:
Δ V OUT is the output ripple voltage.
where:
I L is the maximum inductor or load current for the channel.
D is the duty cycle.
Use this method to determine the input capacitor ripple current
rating for duty cycles between 20% and 80%.
For duty cycles less than 20% or greater than 80%, use an input
capacitor with a ripple current rating of
Δ I L is the inductor ripple current.
ESR is the equivalent series resistance of the output capacitor
(or the parallel combination of ESR of all output capacitors).
ESL is the equivalent series inductance of the output capacitor
(or the parallel combination of ESL of all capacitors).
Note that the factors of 8 and 4 in Equation 5 would normally
be 2π for sinusoidal waveforms, but the ripple current wave-
form in this application is triangular. Parallel combinations
I RIPPLE > 0.4 I L
(3)
of different types of capacitors, for example, a large aluminum
OUTPUT LC FILTER
The output LC filter smoothes the switched voltage at SW,
making the output voltage an almost dc voltage. Choose the
output LC filter to achieve the desired output ripple voltage.
Because the output LC filter is part of the regulator negative-
feedback control loop, the choice of the output LC filter
components affects the regulation control loop stability.
Choose an inductor value such that the inductor ripple current
is approximately 1/3 of the maximum dc output load current.
Using a larger value inductor results in a physical size larger
than required and using a smaller value results in increased
electrolytic in parallel with MLCCs, may give different results.
Usually the impedance is dominated by ESR at the switching
frequency so this equation reduces to
Δ V OUT ? Δ I L ESR (6)
Electrolytic capacitors have significant ESL also, on the order
of 5 nH to 20 nH, depending on type, size, and geometry; and
PCB traces contribute some ESR and ESL as well. However,
using the maximum ESR rating from a capacitor data sheet
usually provides some margin such that measuring the ESL is
not usually required.
losses in the inductor and/or MOSFET switches.
Rev. C | Page 12 of 24
相关PDF资料 |
PDF描述 |
|---|---|
| ADP1822ARQZ-R7 | IC REG CTRLR BUCK PWM VM 24-QSOP |
| ADP1823ACPZ-R7 | IC REG CTRLR BUCK PWM VM 32LFCSP |
| ADP1828ACPZ-R7 | IC REG CTRLR BUCK PWM VM 20LFCSP |
| ADP1829ACPZ-R7 | IC REG CTRLR BUCK PWM VM 32LFCSP |
| ADP1850ACPZ-R7 | IC REG CTRLR BUCK PWM CM 32LFCSP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP1821-BL1-EVZ | 制造商:Analog Devices 功能描述:Evaluation Board For Step-Down DC-To-DC Controller 制造商:Analog Devices 功能描述:BLANK ADISIMPOWER EVAL ADP1821 - Boxed Product (Development Kits) |
| ADP1821-BL2-EVZ | 制造商:Analog Devices 功能描述:Evaluation Board For Step-Down DC-To-DC Controller 制造商:Analog Devices 功能描述:BLANK ADISIMPOWER EVAL ADP1821 - Boxed Product (Development Kits) |
| ADP1821-EVAL | 功能描述:电源管理IC开发工具 Evaluation Board I.C. RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| ADP1822 | 制造商:AD 制造商全称:Analog Devices 功能描述:PWM, Step-Down DC-to-DC Controller with Margining and Tracking |
| ADP1822ARQZ-R7 | 功能描述:IC REG CTRLR BUCK PWM VM 24-QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:75 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.3 V ~ 13.5 V 降压:是 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:0°C ~ 70°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:管件 产品目录页面:1051 (CN2011-ZH PDF) 其它名称:296-2543-5 |
发布紧急采购，3分钟左右您将得到回复。