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| 型号： | ADP1874-0.6-EVALZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 22/44页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR ADP1874 |
| 标准包装： | 1 |
| 系列： | * |
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ADP1874/ADP1875
HS
REPEATED CURRENT-LIMIT
VIOLATION DETECTED
Data Sheet
A PREDETERMINED NUMBER
SOFT START IS
CLIM
OF PULSES IS COUNTED TO REINITIALIZED TO
ALLOW THE CONVERTER MONITOR IF THE
TO COOL DOWN
VIOLATION
STILL EXISTS
ZERO
CURRENT
Figure 73. Idle Mode Entry Sequence Due to Current-Limit Violation
HICCUP MODE DURING SHORT CIRCUIT
A current-limit violation occurs when the current across the
source and drain of the lower side MOSFET exceeds the current-
limit setpoint. When 16 current-limit violations are detected,
the controller enters idle mode and turns off the MOSFETs for
6 ms, allowing the converter to cool down. Then, the controller
reestablishes soft start and begins to cause the output to ramp up
again (see Figure 73). While the output ramps up, CS amplifier
output is monitored to determine if the violation is still present.
If it is still present, the idle event occurs again, followed by the full
ADP1875 POWER SAVING MODE (PSM)
A power saving mode is provided in the ADP1875 . The ADP1875
operates in the discontinuous conduction mode (DCM) and
pulse skips at light load to medium load currents. The controller
outputs pulses as necessary to maintain output regulation. Unlike
the continuous conduction mode (CCM), DCM operation
prevents negative current, thus allowing improved system
efficiency at light loads. Current in the reverse direction through
this pathway, however, results in power dissipation and therefore
a decrease in efficiency.
chip, power-down sequence. This cycle continues until the
violation no longer exists. If the violation disappears, the converter
is allowed to switch normally, maintaining regulation.
SYNCHRONOUS RECTIFIER
The ADP1874 / ADP1875 employ internal MOSFET drivers for
HS
t ON
the external upper side and lower side MOSFETs. The low-side
synchronous rectifier not only improves overall conduction
LS
t OFF
HS AND LS ARE OFF
OR IN IDLE MODE
efficiency but it also ensures proper charging of the bootstrap
capacitor located at the upper side driver input. This is beneficial
during startup to provide sufficient drive signal to the external
upper side MOSFET and to attain fast turn-on response, which is
essential for minimizing switching losses. The integrated upper
I LOAD
AS THE INDUCTOR
CURRENT APPROACHES
ZERO CURRENT, THE STATE
MACHINE TURNS OFF THE
LOWER-SIDE MOSFET.
side and lower side MOSFET drivers operate in complementary
fashion with built-in anti cross-conduction circuitry to prevent
unwanted shoot-through current that may potentially damage the
MOSFETs or reduce efficiency because of excessive power loss.
0A
Figure 74. Discontinuous Mode of Operation (DCM)
To minimize the chance of negative inductor current buildup,
an on-board zero-cross comparator turns off all upper side and
lower side switching activities when the inductor current
approaches the zero current line, causing the system to enter
idle mode, where the upper side and lower side MOSFETs are
turned off. To ensure idle mode entry, a 10 mV offset, connected in
ZERO-CROSS
COMPARATOR
LS
SW
10mV
Q2
I Q2
Figure 75. Zero-Cross Comparator with 10 mV of Offset
Rev. A | Page 22 of 44
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP1874-1.0-EVALZ | 功能描述:BOARD EVAL FOR ADP1874 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 |
| ADP1874ARQZ-0.3-R7 | 功能描述:IC REG CTRLR BUCK PWM CM 16-QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| ADP1874ARQZ-0.6-R7 | 功能描述:IC REG CTRLR BUCK PWM CM 16-QSOP 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) |
| ADP1874ARQZ-1.0-R7 | 功能描述:IC REG CTRLR BUCK PWM CM 16-QSOP 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) |
| ADP1875 | 制造商:AD 制造商全称:Analog Devices 功能描述:Synchronous Buck Controller with Constant On-Time and Valley Current Mode |
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