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参数资料
| 型号： | LTC3568EDD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/18页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 1.8A 10DFN |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 5 V |
| 输入电压： | 2.5 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 最高 4MHz |
| 电流 - 输出： | 1.8A |
| 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-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-DFN（3x3） |
LTC3568
APPLICATIONS INFORMATION
RUN
SHDN/R T
R T
(3a)
RUN OR V IN
R1 D1
RUN
I TH
R C
SHDN/R T
R T
(3b)
SV IN
1M
to ground, pulse skipping operation is selected which
provides the lowest output voltage and current ripple
at the cost of low current efficiency. Applying a voltage
between SV IN – 1V and 1V, results in forced continuous
mode, which creates a fixed output ripple and is capable
of sinking some current (about 1/2 Δ I L ). Since the switch-
ing noise is constant in this mode, it is also the easiest to
filter out. In many cases, the output voltage can be simply
connected to the SYNC/MODE pin, giving the forced con-
tinuous mode, except at startup.
V IN = 3.3V
400μs/DIV
C1 C C
3568 F03
(3c)
Figure 3. SHDN/R T Pin Interfacing and External Soft-Start
internal digital soft-start which steps up a clamp on I TH
over 1024 clock cycles, as can be seen in Figure 4.
The soft-start time can be increased by ramping the volt-
age on I TH during start-up as shown in Figure 3(c). As
the voltage on I TH ramps through its operating range the
internal peak current limit is also ramped at a proportional
linear rate.
V IN
5V/DIV
V OUT
1V/DIV
I L
1A/DIV
3568 F04
V OUT = 2.5V
I LOAD = 1.8A
Figure 4. Digital Soft-Start
Mode Selection and Frequency Synchronization
The SYNC/MODE pin is a multipurpose pin which provides
mode selection and frequency synchronization. Connect-
ing this pin to V IN enables Burst Mode operation, which
provides the best low current efficiency at the cost of a
higher output voltage ripple. When this pin is connected
The LTC3568 can also be synchronized to an external clock
signal by the SYNC/MODE pin. The internal oscillator fre-
quency should be set to 20% lower than the external clock
frequency to ensure adequate slope compensation, since
slope compensation is derived from the internal oscillator.
During synchronization, the mode is set to pulse skipping
and the top switch turn on is synchronized to the rising
edge of the external clock.
Checking Transient Response
The OPTI-LOOP ? compensation allows the transient
response to be optimized for a wide range of loads and
output capacitors. The availability of the I TH pin not only
allows optimization of the control loop behavior but also
provides a DC-coupled and AC filtered closed loop response
test point. 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 the pin.
The I TH external components shown in the Figure 1 circuit
will provide an adequate starting point for most applica-
tions. The series R-C filter sets the dominant pole-zero
loop compensation. The values can be modified slightly
(from 0.5 to 2 times their suggested values) to optimize
transient response once the final PC layout is done and
the particular output capacitor type and value have been
determined. The output capacitors need to be selected
because the 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 I TH pin waveforms
3568fa
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3568IDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 1.8A 10DFN 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 |
| LTC3568IDD#PBF | 制造商:Linear Technology 功能描述:DP-SWREG/Monolithic 4MHz 1.8A Synch St 制造商:Linear Technology 功能描述:DP-SWREG/Monolithic, 4MHz, 1.8A Synch St |
| LTC3568IDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 1.8A 10DFN 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 |
| LTC3569 | 制造商:LINER 制造商全称:Linear Technology 功能描述:7-Channel Confi gurable High Power PMIC |
| LTC3569EFE | 制造商:Linear Technology 功能描述:DC/DC Converter Chip |
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