参数资料
| 型号： | ADP1621ARMZ-R7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 17/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM CM 10-MSOP |
| 标准包装： | 1 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1.5MHz |
| 占空比： | 97% |
| 电源电压： | 2.9 V ~ 5.5 V |
| 降压： | 是 |
| 升压： | 是 |
| 回扫： | 是 |
| 反相： | 是 |
| 倍增器： | 是 |
| 除法器： | 是 |
| Cuk： | 是 |
| 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： | 791 (CN2011-ZH PDF) |
| 配用： | ADP1621-EVALZ-ND - BOARD EVALUATION FOR ADP1621 |
| 其它名称： | ADP1621ARMZ-R7DKR |
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Data Sheet
frequency occurs well below the frequency of the RHP zero. The
location of the RHP zero is determined by the following equation:
ADP1621
Once the compensation resistor, R COMP , is known, set the zero
formed by the resistor and compensation capacitor, C COMP , to
f Z , RHP = ( 1 ? D ) 2 ×
R LOAD
2 π × L
C COMP =
(25)
where f Z,RHP is the RHP zero frequency, and R LOAD is the equivalent
one-fourth of the crossover frequency, or
2
π × f C × R COMP
(31)
load resistance or the output voltage divided by the load current.
To stabilize the regulator, ensure that the regulator crossover
Capacitor C2 is chosen to cancel the zero introduced by the output
ESR × C OUT
frequency is less than or equal to one-fifth of the RHP zero
frequency and less than or equal to one-fifteenth of the switching
frequency. For an initial practical design, choose the crossover
frequency f C to be the lower of
C 2 =
R COMP
where ESR represents the ESR of C OUT .
(32)
and
f C =
f SW
15
(26)
For low ESR output capacitors, such as ceramic capacitors, C2
is small, generally in the range of 10 pF to 400 pF. Because of the
parasitic inductance, resistance, and capacitance of the PCB layout,
the R COMP , C COMP , and C2 values might need to be adjusted by
f C =
f Z , RHP
5
where f C is the crossover frequency, and f SW is the switching
frequency.
(27)
observing the load transient response of the ADP1621 to establish a
stable operating system and achieve optimal transient performance.
For most applications, R COMP is in the range of 5 k? to 100 k?,
and C COMP is in the range of 100 pF to 30 nF.
The regulator loop gain is
REF
g m
COMP
3
A VL
=
V FB
V OUT
× ( 1 ? D ) × g m × | Z COMP | ×
1
n × R CS
× | Z OUT |
(28)
2
R COMP
C COMP
C2
× ( 1 ? D ) × g m × R COMP ×
V FB 1 1
I SC,PK × f SW V + V D ? V IN
1 ? t OFF, MIN × f SW
2 × R S × > R CS × OUT (33)
2 π × f C × C OUT × n × R CS × V OUT
V FB × ( 1 ? D ) × g m
where A VL is the loop gain, V FB is the feedback regulation
voltage (typically 1.215 V), V OUT is the regulated output voltage,
D is the duty cycle, g m is the error amplifier transconductance
gain (typically 300 μS), Z COMP is the impedance of the RC network
from COMP to GND, n is the current-sense amplifier gain
(typically 9.5), R CS is the current-sense resistance, and Z OUT is
the impedance of the load and output capacitor. In the case of
lossless current sensing, as shown in Figure 28, R CS is equal to the
on resistance, R DSON , of the external power MOSFET. Otherwise,
R CS represents the external current-sense resistor, as shown in
To determine the crossover frequency, it is important to note
that at that frequency the compensation impedance, Z COMP , is
dominated by Resistor R COMP , and the output impedance, Z OUT ,
is dominated by the impedance of the output capacitor, C OUT .
When solving for the crossover frequency, the equation is
simplified to
| A VL | =
× = 1
V OUT n × R CS 2 π × f C × C OUT
(29)
where f C is the crossover frequency, R COMP is the compensation
resistor, and C OUT is the output capacitance.
Solving for R COMP gives
R COMP = (30)
Figure 31. Compensation Components
SLOPE COMPENSATION
The ADP1621 includes a circuit that allows adjustable slope
compensation. Slope compensation is required by current-
mode regulators to stabilize the current-control loop when
operating in continuous conduction and the switching duty
cycle is greater than 50%.
Slope compensation is achieved by internally forcing a ramping
current source out of the CS current-sense pin. By placing a resistor
between the CS pin and the current sensing device (the drain of
the external MOSFET in the case of lossless current sensing or
the source of the MOSFET if a current-sense resistor is used), a
voltage is developed across the resistor that is proportional to
the slope-compensation current.
To ensure stability of the current-mode control loop, use a
compensation voltage slope that is equal to or greater than one-
half of the current-sense representation of the inductor current
downslope. Therefore, it follows that
L
where R S is the slope-compensation resistor, I SC,PK is the peak slope-
compensation current, f SW is the switching frequency, R CS is the
current-sense resistor, V OUT is the regulated output voltage, V D is the
forward-voltage drop of the diode, V IN is the input voltage, t OFF,MIN is
the minimum off time, and L is the power-stage inductor. In the
case of lossless current sensing, R CS is equal to the on resistance,
Rev. B | Page 17 of 32
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP1621-BL2-EVZ | 制造商:Analog Devices 功能描述:BLANK ADISIMPOWER EVAL ADP1621 - Boxed Product (Development Kits) |
| ADP1621-BL4-EVZ | 功能描述:BOARD EVALUATION FOR ADP1621 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 |
| ADP1621-EVAL | 制造商:AD 制造商全称:Analog Devices 功能描述:Constant-Frequency, Current-Mode Step-Up DC/DC Controller |
| ADP1621-EVALZ | 功能描述:BOARD EVALUATION FOR ADP1621 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 |
| ADP162ACBZ-1.2-R7 | 功能描述:IC REG LDO 1.2V .15A 4WLCSP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 其它有关文件:LD39015JXX12 View All Specifications 标准包装:1 系列:- 稳压器拓扑结构:正，固定式 输出电压:1.2V 输入电压:1.5 V ~ 5.5 V 电压 - 压降（标准）:- 稳压器数量:1 电流 - 输出:150mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:4-WFBGA，FCBGA 供应商设备封装:4-覆晶（1.07x1.07） 包装:Digi-Reel® 其它名称:497-11958-6 |
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