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参数资料
| 型号： | LTC3408EDD |
| 厂商： | Linear Technology |
| 文件页数： | 6/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK W/BYPASS TXRX 8-DFN |
| 标准包装： | 121 |
| 应用： | 转换器，WCDMA 功率放大器应用 |
| 输入电压： | 2.5 V ~ 5 V |
| 输出数： | 1 |
| 输出电压： | 0.3 V ~ 3.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-WFDFN 裸露焊盘 |
| 供应商设备封装： | 8-DFN-EP（3x3） |
| 包装： | 管件 |
LTC3408
FU CTIO AL DIAGRA
SLOPE
COMP
OSC
OSC
REF
FREQ
÷ 2
–
2 V IN
6
V OUT
8
FB
EA
+
0.85V
–
+
BURST
SLEEP
– +
I COMP
5 ?
7 V IN
V OUT
1
360k
I BCMP
S
R
Q
Q
180k
RS LATCH
SWITCHING
LOGIC
P-CHANNEL
AND
ANTI-
V IN
BLANKING
CIRCUIT
SHOOT-
THRU
4 SW
–
BCMP
RUN
5
1.2V
+
I RCMP
9
3 GND
3408 BD
OPERATIO
(Refer to Functional Diagram)
C IN
V IN
2.7V
TO 5V
?
10 μ F
CER
V IN SW
LTC3408
RUN V OUT
4.7 μ H*
V OUT
3 × V REF
C OUT ** 600mA
4.7 μ F
CER
output voltage can respond quickly to the external refer-
ence voltage by sourcing or sinking current as needed.
TAIYO YUDEN JMK212BJ106MN
REF
REF
GND
3403 F01
* MURATA LQH32CN4R7M11
** TAIYO YUDEN JMK212BJ475MG
?
Controlling the Output Voltage
The output voltage can be dynamically programmed from
0.3V to 3.5V using the REF input. Because the gain to V OUT
Figure 1. Typical Application
Main Control Loop
The LTC3408 uses a constant frequency, current mode step-
down architecture. The main (P-channel MOSFET), syn-
chronous (N-channel MOSFET) and bypass (P-channel
MOSFET) switches are internal. During normal operation,
theinternalmainswitchisturnedoneachcyclewhenthe
oscillator sets the RS latch, and turned off when the cur-
rent comparator, I COMP , resets the RS latch. The peak in-
ductor current at which I COMP resets the RS latch, is con-
trolled by the output of error amplifier EA. When the load
current increases, it causes a slight decrease in the feed-
back voltage, FB, relative to the external reference, which
in turn, causes the EA amplifier’s output voltage to increase
until the average inductor current matches the new load cur-
rent. While the main switch is off, the synchronous switch
is turned on until the beginning of the next clock cycle.
The LTC3408 operates in forced continuous mode where
the inductor current is constantly cycled. In this mode, the
from REF is internally set to 3, the corresponding input
range at REF is 0.1V to 1.167V. V OUT can be modulated
during operation by driving REF with an external DAC.
When REF exceeds 1.2V, a 0.08 ? internal bypass P-channel
MOSFET connects V IN to V OUT , dramatically reducing the
drop across the inductor and the main switch.
Short-Circuit Protection
A current sense comparator monitors the current across
the bypass P-channel MOSFET with a trip current of about
2.5A. When this current is exceeded during a V OUT short
to ground, the bypass P-channel MOSFET is immediately
turned off. The propagation delay of the current sensing
comparator, I BCMP , detecting an overcurrent condition to
turning off the bypass P-channel MOSFET is approxmately
100ns. Once the bypass P-channel MOSFET is off for about
10 μ s to 20 μ s, it is allowed to turn back on. The initial
current limit is then lowered to about 1.6A after the first
current limit trip. If the short to ground persists, the cur-
rent comparator will trip at the lower current limit, turning
3408f
6
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相关代理商/技术参数 |
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| LTC3408EDD#PBF | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3408EDD#TR | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3408EDD#TRPBF | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3409 | 制造商:LINER 制造商全称:Linear Technology 功能描述:600mA Low Vin Buck Regulator in 3mm x 3mm DFN |
| LTC3409A | 制造商:LINER 制造商全称:Linear Technology 功能描述:600mA Low VIN Buck Regulator in 3mm × 3mm DFN |
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