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参数资料
| 型号： | ADP2303-EVALZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 14/28页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR ADP2303 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 电流 - 输出： | 3A |
| 输入电压： | 3 ~ 20 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 700kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | ADP2303 |
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ADP2302/ADP2303
THEORY OF OPERATION
The ADP2302/ADP2303 are nonsynchronous, step-down,
dc-to-dc regulators, each with an integrated high-side power
MOSFET. The high switching frequency and 8-lead SOIC
package provide a small, step-down, dc-to-dc regulator
solution.
The ADP2302/ADP2303 can operate with an input voltage from
3.0 V to 20 V while regulating an output voltage down to 0.8 V.
The ADP2302 can provide 2 A maximum continuous output
current, and the ADP2303 can provide 3 A maximum
continuous output current.
BASIC OPERATION
The ADP2302/ADP2303 use the fixed-frequency, peak current-
mode PWM control architecture from medium to high loads,
but shift to a pulse-skip mode control scheme at light loads to
reduce the switching power losses and improve efficiency. When
these devices operate in fixed-frequency PWM mode, output
regulation is achieved by controlling the duty cycle of the integrated
MOSFET. While the devices are operating in pulse-skip mode at
light loads, the output voltage is controlled in a hysteretic
manner with higher output ripple. In this mode of operation, the
regulator periodically stops switching for a few cycles, thus
keeping the conversion losses minimal to improve efficiency.
PWM MODE
In PWM mode, the ADP2302/ADP2303 operate at a fixed
frequency, set by an internal oscillator. At the start of each
oscillator cycle, the MOSFET switch is turned on, providing a
positive voltage across the inductor. The inductor current
increases until the current-sense signal crosses the peak
inductor current threshold that turns off the MOSFET switch;
this threshold is set by the error amplifier output. During the
MOSFET off time, the inductor current declines through the
external diode until the next oscillator clock pulse comes and a
new cycle starts.
POWER SAVING MODE
To achieve higher efficiency, the ADP2302/ADP2303 smoothly
transition to the pulse-skip mode when the output load decreases
below the pulse-skip current threshold. When the output vol-
tage dips below the regulation, the ADP2302/ADP2303 enter
PWM mode for a few oscillator cycles until the voltage increases
to regulation range. During the idle time between bursts, the
MOSFET switch is turned off, and the output capacitor supplies
all the output current.
Because the pulse-skip mode comparator monitors the internal
compensation node, which represents the peak inductor current
information, the average pulse-skip load current threshold
depends on the input voltage (V IN ), the output voltage (V OUT ),
the inductor, and the output capacitor.
Data Sheet
Because the output voltage occasionally dips below regulation
and then recovers, the output voltage ripple in the power saving
mode is larger than the ripple in the PWM mode of operation.
BOOTSTRAP CIRCUITRY
The ADP2302/ADP2303 each have an integrated boot regulator,
which requires that a 0.1 μF ceramic capacitor (X5R or X7R) be
placed between the BST and SW pins to provide the gate drive
voltage for the high-side MOSFET. There is at least a 1.2 V
difference between the BST and SW pins to turn on the high-side
MOSFET. This voltage should not exceed 5.5 V in case the BST
pin is supplied with the external voltage source through a diode.
The ADP2302/ADP2303 generate a typical 5.0 V bootstrap voltage
for the gate drive circuit by differentially sensing and regulating
the voltage between the BST and SW pins. There is a diode
integrated on the chip that blocks the reverse voltage between the
VIN and BST pins when the MOSFET switch is turned on.
PRECISION ENABLE
The ADP2302/ADP2303 provide a precision enable circuit that
has 1.2 V reference threshold with 100 mV hysteresis. When the
voltage at the EN pin is greater than 1.2 V (typical), the part is
enabled. If the EN voltage falls below 1.1 V (typical), the chip
is disabled. The precision enable threshold voltage allows the
ADP2302/ADP2303 to be easily sequenced from other input/
output supplies. It also can be used as a programmable UVLO
input by using a resistive divider. An internal 1.2 μA pull-down
current prevents errors if the EN pin is left floating.
INTEGRATED SOFT START
The ADP2302/ADP2303 have an internal digital soft start
circuitry to limit the output voltage rise time and reduce
the inrush current at power up. The soft start time is fixed at
2048 clock cycles.
CURRENT LIMIT
The ADP2302/ADP2303 include current-limit protection circuitry
to limit the amount of positive current flowing through the high-
side MOSFET switch. The positive current limit on the power
switch limits the amount of current that can flow from the input
to the output.
SHORT-CIRCUIT PROTECTION
The ADP2302/ADP2303 include frequency foldback to prevent
output current runaway when there is a hard short on the output.
The switching frequency is reduced when the voltage at the FB pin
drops below a certain value, which allows more time for the
inductor current to decline, but increases the ripple current while
regulating the peak current. This results in a reduction in average
output current and prevents output current runaway. The corre-
lation between the switching frequency and the FB pin voltage
Rev. A | Page 14 of 28
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP2303-EVALZ | 制造商:Analog Devices 功能描述:ADP2303, DC TO DC REGULATOR, STEP DOWN, |
| ADP2311-1-EVALZ | 功能描述:ADP2311 - DC/DC, Step Down 2, Non-Isolated Outputs Evaluation Board 制造商:analog devices inc. 系列:- 零件状态:有效 主要用途:DC/DC，步降 输出和类型:2，非隔离 功率 - 输出:- 电压 - 输出:1.2V，3.3V 电流 - 输出:1A，1A 电压 - 输入:4.5 V ~ 18 V 稳压器拓扑:降压 频率 - 开关:300kHz 板类型:完全填充 所含物品:板 使用的 IC/零件:ADP2311 标准包装:1 |
| ADP2311ACPZ-1-R7 | 功能描述:Buck Switching Regulator IC Positive Adjustable 0.6V 2 Output 1A 24-WFQFN Exposed Pad, CSP 制造商:analog devices inc. 系列:- 包装:剪切带（CT） 零件状态:有效 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:2 电压 - 输入（最小值）:4.5V 电压 - 输入（最大值）:18V 电压 - 输出（最小值/固定）:0.6V 电压 - 输出（最大值）:18V 电流 - 输出:1A 频率 - 开关:300kHz 同步整流器:是 工作温度:-40°C ~ 125°C （TJ） 安装类型:表面贴装 封装/外壳:24-WFQFN 裸露焊盘，CSP 供应商器件封装:24-LFCSP-WQ（4x4） 标准包装:1 |
| ADP2311ACPZ-2-R7 | 功能描述:Buck Switching Regulator IC Positive Adjustable 0.6V 2 Output 1A 24-WFQFN Exposed Pad, CSP 制造商:analog devices inc. 系列:- 包装:剪切带（CT） 零件状态:有效 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:2 电压 - 输入（最小值）:4.5V 电压 - 输入（最大值）:18V 电压 - 输出（最小值/固定）:0.6V 电压 - 输出（最大值）:18V 电流 - 输出:1A 频率 - 开关:300kHz 同步整流器:是 工作温度:-40°C ~ 125°C （TJ） 安装类型:表面贴装 封装/外壳:24-WFQFN 裸露焊盘，CSP 供应商器件封装:24-LFCSP-WQ（4x4） 标准包装:1 |
| ADP2311ACPZ-3-R7 | 功能描述:Buck Switching Regulator IC Positive Adjustable 0.6V 2 Output 1A 24-WFQFN Exposed Pad, CSP 制造商:analog devices inc. 系列:- 包装:剪切带（CT） 零件状态:有效 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:2 电压 - 输入（最小值）:4.5V 电压 - 输入（最大值）:18V 电压 - 输出（最小值/固定）:0.6V 电压 - 输出（最大值）:18V 电流 - 输出:1A 频率 - 开关:300kHz 同步整流器:是 工作温度:-40°C ~ 125°C （TJ） 安装类型:表面贴装 封装/外壳:24-WFQFN 裸露焊盘，CSP 供应商器件封装:24-LFCSP-WQ（4x4） 标准包装:1 |
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