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| 型号： | LTC3613EWKH#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 24/36页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 15A 56-QFN |
| 标准包装： | 40 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 5.5 V |
| 输入电压： | 4.5 V ~ 24 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz ~ 1MHz |
| 电流 - 输出： | 15A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 56-VFQFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 56-QFN 多焊盘（7x9） |
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LTC3613
APPLICATIONS INFORMATION
To further limit current in the event of a short circuit to
ground, the LTC3613 includes foldback current limiting.
If the output fails by more than 50%, then the maximum
sense voltage is progressively lowered to about one-fourth
of its full value.
If the output exceeds 7.5% of the programmed value,
then it is considered as an overvoltage (OV) condition.
In such a case, the top MOSFET is immediately turned
off and the bottom MOSFET is turned on indefinitely until
the OV condition is removed. Current limiting is not ac-
tive during an OV. If the output returns to a nominal level,
then normal operation resumes. If the OV persists a long
time, the current through the inductor could exceed its
maximum rating.
OPTI-LOOP Compensation
OPTI-LOOP compensation, through the availability of the
ITH pin, allows the transient response to be optimized for
a wide range of loads and output capacitors. The ITH pin
not only allows optimization of the control loop behavior
but also provides a test point for the step-down regulator ’s
DC-coupled and AC-filtered closed-loop response. The DC
step, rise time and settling at this test point truly reflects the
closed-loop response. Assuming a predominantly second
order system, phase margin and/or damping factor can be
estimated using the percentage of overshoot seen at this
pin. The bandwidth can also be estimated by examining
the rise time at this pin.
The ITH series R ITH -C ITH1 filter sets the dominant pole-zero
loop compensation. Additionally, a small capacitor placed
from the ITH pin to SGND, C ITH2 , may be required to at-
tenuate high frequency noise. The values can be modified
to optimize transient response once the final PCB layout
is done and the particular output capacitor type and value
have been determined. The output capacitors need to be
selected because their various types and values determine
the loop feedback factor gain and phase. An output current
pulse of 20% to 100% of full load current having a rise
time of 1μs to 10μs will produce output voltage and ITH
pin waveforms that will give a sense of the overall loop
stability without breaking the feedback loop. The general
goal of OPTI-LOOP compensation is to realize a fast but
stable ITH response with minimal output droop due to
the load step. For a detailed explanation of OPTI-LOOP
compensation, refer to Application Note 76.
Switching regulators take several cycles to respond to a
step in load current. When a load step occurs, V OUT im-
mediately shifts by an amount equal to Δ I LOAD ? ESR, where
ESR is the effective series resistance of C OUT . Δ I LOAD also
begins to charge or discharge C OUT , generating a feedback
error signal used by the regulator to return V OUT to its
steady-state value. During this recovery time, V OUT can
be monitored for overshoot or ringing that would indicate
a stability problem.
Connecting a resistive load in series with a power MOSFET,
then placing the two directly across the output capacitor
and driving the gate with an appropriate signal generator
is a practical way to produce a realistic load-step condi-
tion. The initial output voltage step resulting from the step
change in output current may not be within the bandwidth
of the feedback loop, so this signal cannot be used to
determine phase margin. This is why it is better to look
at the ITH pin signal which is in the feedback loop and
is the filtered and compensated feedback loop response.
The gain of the loop increases with R ITH and the bandwidth
of the loop increases with decreasing C ITH1 . If R ITH is
increased by the same factor that C ITH1 is decreased, the
zero frequency will be kept the same, thereby keeping the
phase the same in the most critical frequency range of the
feedback loop. In addition, a feedforward capacitor, C FF , can
be added to improve the high frequency response, as shown
in Figure 1. Capacitor C FF provides phase lead by creating
a high frequency zero with R FB2 which improves the phase
margin. The output voltage settling behavior is related to
the stability of the closed-loop system and will demonstrate
overall performance of the step-down regulator.
3613fa
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| LTC3613IWKH#PBF | 功能描述:IC REG BUCK SYNC ADJ 15A 56QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LTC3613IWKH#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 15A 56QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LTC3614EUDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 4A 24QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LTC3614EUDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 4A 24QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC3614IUDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 4A 24QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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