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| 型号： | ADP1823ACPZ-R7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 16/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 32LFCSP |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 720kHz |
| 占空比： | 90% |
| 电源电压： | 3.7 V ~ 20 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 ~ 125°C |
| 封装/外壳： | 32-VFQFN 裸露焊盘，CSP |
| 包装： | 标准包装 |
| 产品目录页面： | 791 (CN2011-ZH PDF) |
| 其它名称： | ADP1823ACPZ-R7DKR |
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ADP1823
APPLICATIONS INFORMATION
SELECTING THE INPUT CAPACITOR
Choose the inductor value by
V IN ? V OUT ? V OUT
? V
?
?
The input current to a buck converter is a pulse waveform. It is
zero when the high-side switch is off and approximately equal
to the load current when it is on. The input capacitor carries the
L =
Δ I L f SW ? IN
?
?
?
(4)
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 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 sufficiently high current rating
as calculated in Equation 1, along with a 10 μF ceramic capacitor.
Select an input bulk capacitor based on its ripple current rating.
If both Channel 1 and Channel 2 maximum output load currents
are about the same, the input ripple current is less than half of
the higher of the output load currents. In this case, use an input
capacitor with a ripple current rating greater than half of the
highest load current.
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
equivalent series resistance (ESR), and the equivalent series
inductance (ESL). The output voltage ripple can be
I RIPPLE >
Δ V OUT = Δ I L ? ESR +
?
+ 4 f SW ESL ?
?
I L
2
If the Output 1 and Output 2 load currents are significantly
(1)
approximated with
?
?
1
8 f SW C OUT
?
?
(5)
D =
V OUT
different (if the smaller is less than 50% of the larger), the
procedure in Equation 1 yields a larger input capacitor than
required. In this case, the input capacitor can be chosen as in
the case of a single phase converter with only the higher load
current; therefore, first determine the duty cycle of the output
with the larger load current.
(2)
V IN
In this case, the input capacitor ripple current is approximately
where:
Δ V OUT is the output ripple voltage.
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 waveform in
I RIPPLE ≈ I L D ( 1 ? D )
(3)
this application is triangular. Parallel combinations of different
types of capacitors, for example, a large aluminum electrolytic
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
in parallel with MLCCs, may give different results.
Usually, the impedance is dominated by ESR at the switching
frequency, as stated in the maximum ESR rating on the
capacitor data sheet, so this equation reduces to
rating for duty cycles between 20% and 80%.
Δ V OUT ? Δ I L ESR
(6)
For duty cycles less than 20% or greater than 80%, use an input
capacitor with a ripple current rating of I RIPPLE > 0.4 I L .
Selecting the Output LC Filter
The output LC filter attenuates the switching voltage, making
the output an almost dc voltage. The output LC filter characteris-
tics determine the residual output ripple voltage.
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 the capacitor data sheet usually
provides some margin such that measuring the ESL is not
usually required.
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 is required, and using a smaller value results in increased
losses in the inductor and MOSFETs.
Rev. D | Page 16 of 32
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP1823-EVAL | 功能描述:BOARD EVAL FOR ADP1823 RoHS:否 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 标准包装:1 系列:- 主要目的:DC/DC，步降 输出及类型:1，非隔离 功率 - 输出:- 输出电压:3.3V 电流 - 输出:3A 输入电压:4.5 V ~ 28 V 稳压器拓扑结构:降压 频率 - 开关:250kHz 板类型:完全填充 已供物品:板 已用 IC / 零件:L7981 其它名称:497-12113STEVAL-ISA094V1-ND |
| ADP1828 | 制造商:AD 制造商全称:Analog Devices 功能描述:Synchronous Buck PWM, Step-Down, DC-to-DC Controller |
| ADP1828ACPZ-R7 | 功能描述:IC REG CTRLR BUCK PWM VM 20LFCSP 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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 ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| ADP1828-BL1-EVZ | 制造商:Analog Devices 功能描述:BLANK ADISIMPOWER EVAL ADP1828 - Boxed Product (Development Kits) |
| ADP1828-BL2-EVZ | 制造商:Analog Devices 功能描述:BLANK ADISIMPOWER EVAL ADP1828 - Boxed Product (Development Kits) |
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