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参数资料
| 型号： | ADP1872ARMZ-1.0-R7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 24/40页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 10-MSOP |
| 标准包装： | 1 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 45% |
| 电源电压： | 3 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： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 标准包装 |
| 产品目录页面： | 792 (CN2011-ZH PDF) |
| 其它名称： | ADP1872ARMZ-1.0-R7DKR |
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R COMP ( f CROSS + f ZERO )
Z COMP =
ADP1872/ADP1873
Ceramic capacitors are known to have low ESR. However, the
trade-off of using X5R technology is that up to 80% of its capaci-
tance may be lost due to derating because the voltage applied
across the capacitor is increased (see Figure 79). Although X7R
series capacitors can also be used, the available selection is
limited to only up to 22 μF.
20
Data Sheet
Error Amplifier Output Impedance (Z COMP )
Assuming C C2 is significantly smaller than C COMP , C C2 can be
omitted from the output impedance equation of the error amplifier.
The transfer function simplifies to
f CROSS
f CROSS =
× f SW
10
0
–10
–20
–30
–40
–50
–60
–70
–80
X7R (50V)
X5R (25V)
X5R (16V)
10μF TDK 25V, X7R, 1210 C3225X7R1E106M
and
1
12
where f ZERO , the zero frequency, is set to be 1/4 th of the crossover
frequency for the ADP1872.
Error Amplifier Gain (G M )
The error amplifier gain (transconductance) is
G M = 500 μA/V
H = 1 V/V = G M × G CS ×
× Z COMP × Z FILT
G CS =
1
A CS × R ON
f CROSS =
f SW
f ZERO =
–90 22μF MURATA 25V, X7R, 1210 GRM32ER71E226KE15L
47μF MURATA 16V, X5R, 1210 GRM32ER61C476KE15L
–100
0 5 10 15 20 25 30
DC VOLTAGE (V DC )
Figure 79. Capacitance vs. DC Voltage Characteristics for Ceramic Capacitors
Electrolytic capacitors satisfy the bulk capacitance requirements
for most high current applications. Because the ESR of electrolytic
capacitors is much higher than that of ceramic capacitors, when
using electrolytic capacitors, several MLCCs should be mounted
in parallel to reduce the overall series resistance.
COMPENSATION NETWORK
Due to its current-mode architecture, the ADP1872/ADP1873
require Type II compensation. To determine the component
values needed for compensation (resistance and capacitance
values), it is necessary to examine the converter’s overall loop
gain (H) at the unity gain frequency (f SW /10) when H = 1 V/V.
V OUT
V REF
Examining each variable at high frequency enables the unity
gain transfer function to be simplified to provide expressions
for the R COMP and C COMP component values.
Output Filter Impedance (Z FILT )
Examining the filter’s transfer function at high frequencies
simplifies to
Current-Sense Loop Gain (G CS )
The current-sense loop gain is
(A/V)
where:
A CS (V/V) is programmable for 3 V/V, 6 V/V, 12 V/V, and 24 V/V
(see the Programming Resistor (RES) Detect Circuit and Valley
Current-Limit Setting sections).
R ON is the channel impedance of the lower side MOSFET.
Crossover Frequency
The crossover frequency is the frequency at which the overall
loop (system) gain is 0 dB (H = 1 V/V). It is recommended for
current-mode converters, such as the ADP1872, that the user
set the crossover frequency between 1/10 th and 1/15 th of the
switching frequency.
1
12
The relationship between C COMP and f ZERO (zero frequency) is
1
2 π × R COMP × C COMP
The zero frequency is set to 1/4 th of the crossover frequency.
Combining all of the above parameters results in
V
Z FILTER =
1
sC OUT
R COMP =
f CROSS
f CROSS + f ZERO
×
2 π f CROSS C OUT
G M G CS
× OUT
V REF
at the crossover frequency (s = 2πf CROSS ).
Rev. B | Page 24 of 40
C COMP =
1
2 × π × R COMP × f ZERO
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP1872-BL1-EVZ | 功能描述:EVAL BOARD FOR ADP1872 RoHS:是 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 |
| ADP1872-BL2-EVZ | 功能描述:EVAL BOARD FOR ADP1872 RoHS:是 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 |
| ADP1873-0.3-EVALZ | 功能描述:BOARD EVAL FOR ADP1873-0.3 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:* 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ADP1873-0.6-EVALZ | 功能描述:BOARD EVAL FOR ADP1873-0.6 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:* 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ADP1873-1.0-EVALZ | 功能描述:BOARD EVAL FOR ADP1873-1.0 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:* 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
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