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参数资料
| 型号： | ADP1871-1.0-EVALZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 24/44页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR ADP1871-1.0 |
| 标准包装： | 1 |
| 系列： | * |
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ADP1870/ADP1871
APPLICATIONS INFORMATION
Data Sheet
FEEDBACK RESISTOR DIVIDER
The required resistor divider network can be determined for a
given V OUT value because the internal band gap reference (V REF )
is fixed at 0.6 V. Selecting values for R T and R B determines the
minimum output load current of the converter. Therefore, for a
Table 8. Recommended Inductors
L DCR I SAT Dimensions
(μH) (mΩ) (A) (mm)
0.12 0.33 55 10.2 × 7
0.22 0.33 30 10.2 × 7
0.47 0.67 50 13.2 × 12.8
Manufacturer
Würth Elek.
Würth Elek.
Würth Elek.
Model
Number
744303012
744303022
744355147
( V OUT ? 0 . 6 V)
R T = R B ×
given value of R B , the R T value can be determined through the
following expression:
0 . 6 V
INDUCTOR SELECTION
0.72
0.9
1.2
1.0
1.4
2.0
0.8
1.3
1.6
1.8
3.3
3.2
2.6
2.5
35
28
25
20
24
22
16.5
10.5 × 10.2
13 × 12.8
10.5 × 10.2
10.5 × 10.2
14 × 12.8
13.2 × 12.8
12.5 × 12.5
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
Würth Elek.
AIC Technology
744325072
744355090
744325120
7443552100
744318180
7443551200
CEP125U-R80
The inductor value is inversely proportional to the inductor
ripple current. The peak-to-peak ripple current is given by
OUTPUT RIPPLE VOLTAGE (ΔV RR )
? I L = K I × I LOAD ≈
I LOAD
3
The output ripple voltage is the ac component of the dc output
voltage during steady state. For a ripple error of 1.0%, the
( V IN ? V OUT ) V OUT
? I L × f SW
where K I is typically 0.33.
The equation for the inductor value is given by
L = ×
V IN
where:
V IN is the high voltage input.
V OUT is the desired output voltage.
f SW is the controller switching frequency (300 kHz, 600 kHz, and
1.0 MHz).
When selecting the inductor, choose an inductor saturation
rating that is above the peak current level, and then calculate
the inductor current ripple (see the Valley Current-Limit
output capacitor value needed to achieve this tolerance can be
determined using the following equation. (Note that an
accuracy of 1.0% is possible only during steady state conditions,
not during load transients.)
? V RR = ( 0 . 01 ) × V OUT
OUTPUT CAPACITOR SELECTION
The primary objective of the output capacitor is to facilitate the
reduction of the output voltage ripple; however, the output
capacitor also assists in the output voltage recovery during load
transient events. For a given load current step, the output
voltage ripple generated during this step event is inversely
proportional to the value chosen for the output capacitor. The
speed at which the output voltage settles during this recovery
period depends on where the crossover frequency (loop
52
50
48
46
44
42
40
38
36
34
32
30
ΔI = 50%
ΔI = 40%
ΔI = 33%
bandwidth) is set. This crossover frequency is determined by
the output capacitor, the equivalent series resistance (ESR) of
the capacitor, and the compensation network.
To calculate the small-signal voltage ripple (output ripple
voltage) at the steady state operating point, use the following
equation:
C OUT = ? I L × ? ?
1
?
28
26
24
22
20
?
?
?
8 × f SW × [ ? V RIPPLE ? ( ? I L × ESR ) ] ? ?
18
16
14
12
10
where ESR is the equivalent series resistance of the output
capacitors.
8
6
8
10
12
14
16
18
20
22
24
26
28
30
To calculate the output load step, use the following equation:
VALLEY CURRENT LIMIT (A)
Figure 79. Peak Inductor Current vs. Valley Current Limit for 33%, 40%, and
50% of Inductor Ripple Current
C OUT = 2 ×
f SW
? I LOAD
× ( ? V DROOP ? ( ? I LOAD × ESR ))
where Δ V DROOP is the amount that V OUT is allowed to deviate for
a given positive load current step (ΔI LOAD ).
Rev. B | Page 24 of 44
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| ADP1871ACPZ-0.3-R7 | 功能描述:IC REG CTRLR BUCK PWM CM 10LFCSP 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) |
| ADP1871ACPZ-0.6-R7 | 功能描述:IC REG CTRLR BUCK PWM CM 10LFCSP 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) |
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| ADP1871ARMZ-0.3-R7 | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP 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) |
| ADP1871ARMZ-0.6-R7 | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP 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) |
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