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参数资料
| 型号： | LT1680CN |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | High Power DC/DC Step-Up Controller |
| 中文描述： | SWITCHING CONTROLLER, 200 kHz SWITCHING FREQ-MAX, PDIP16 |
| 封装： | 0.300 INCH, PLASTIC, DIP-16 |
| 文件页数： | 11/16页 |
| 文件大小： | 322K |
| 代理商： | LT1680CN |
11
LT1680
additional current can be minimized by making the con-
nection through an external resistor (100k is typically used).
When shutting down the LT1680, the RUN/SHDN pin volt-
age must remain between the shutdown threshold (~1.13V)
and a minimum shutdown control limit voltage (see Fig-
ure 4) for a least 25
μ
s. If a digital input or fast moving
clamp is used, this can be achieved by forcing a shutdown
control voltage above the minimum limit or by using a
simple integrator to increase the fall time of the input sig-
nal. A single pole integrator stage must have a
τ
≥
(7)(10
–5
).
APPLICATIO
S I
FOR
ATIO
U
W
U
U
TEMPERATURE (
°
C)
500
M
600
700
800
–40
–20
0
20
1680 F04
40
60
80
Figure 4. Minimum Shutdown Control Limit vs Temperature
Figure 5 is an example of a digital control input clamp. A
logic high signal pulls the RUN/SHDN pin above its turn-
on threshold through the diode. When a shutdown (logic
low) signal is received, the RUN/SHDN pin is forced to
0.95V via the resistor divider until shutdown is fully estab-
lished and the 5V
REF
voltage collapses.
R1
43k
DIGITAL
INPUT
R2
10k
1N914
1680 F05
5V
REF
LT1680
RUN/SHDN
Figure 6 is an example of a digital control integration stage
at the RUN/SHDN input. The integrator has a
τ
= (10)(10
3
)
(10)(10
–9
) = (1.0)(10
–4
). This circuit technique, however,
delays initiation of controller shutdown about 125
μ
s from
the reception of the shutdown signal (5V – 0V transition).
Figure 5. Digital Input Shutdown Level Control
R1
10k
C1
10nF
DIGITAL
INPUT
1680 F06
RUN/SHDN
LT1680
Figure 6. Digital Input Shutdown Integration Control
Figure 7 is an example of an integrator stage coupled with
a 24V input power supply sequencing circuit similar to that
shown in Figure 3. The integrator stage allows use of an
active shutdown clamp for implementation of both user-
controlled shutdown and input power supply sequencing
protection.
Inductor Selection
The inductor for an LT1680 converter is selected based on
output power, operating frequency and efficiency require-
0.8V
1680 F08
2V
2.5V
(vl)
SYNC
V
CT
(vh)
FREE RUN
SYNCHRONIZED
Figure 8. Free Run and Synchronized Oscillator
Waveforms (at C
T
Pin)
R1
160k
R2
10k
SHDN
R4
10k
R3
390k
V
IN
24V
C1
10nF
1680 F07
LT1680
5V
REF
RUN/SHDN
Figure 7. Input Supply Sequencing with
User-Controlled Shutdown
Oscillator Synchronization
The LT1680 oscillator generates a modified sawtooth
waveform at the C
T
pin between low and high thresholds
of 0.8V (vl) and 2.5V (vh) respectively. The oscillator can
be synchronized by driving a TTL level pulse into the SYNC
pin. This pin connects to a one shot circuit that reduces the
oscillator high threshold to 2V for about 200ns. The SYNC
input signal should have minimum on/off times of
≥
1
μ
s.
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PDF描述 |
|---|---|
| LT1680CSW | High Power DC/DC Step-Up Controller |
| LT1680I | High Power DC/DC Step-Up Controller |
| LT1680IN | High Power DC/DC Step-Up Controller |
| LT1680ISW | High Power DC/DC Step-Up Controller |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1680CN#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-DIP 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 |
| LT1680CSW | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC RoHS:否 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) |
| LT1680CSW#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC 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 |
| LT1680CSW#TR | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC RoHS:否 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) |
| LT1680CSW#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC 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) |
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