参数资料
| 型号： | LT3493IDCB#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 1.2A 6DFN |
| 标准包装： | 500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.78 V ~ 34.2 V |
| 输入电压： | 3.6 V ~ 36 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 750kHz |
| 电流 - 输出： | 1.2A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 6-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 6-DFN-EP（2x3） |
LT3493
APPLICATIONS INFORMATION
Table 2. Capacitor Vendors
VENDOR
Panasonic
PHONE
(714) 373-7366
URL
www.panasonic.com
PART SERIES COMMENTS
Ceramic,
Polymer,
EEF Series
Tantalum
Kemet
Sanyo
(864) 963-6300
(408) 749-9714
www.kemet.com
www.sanyovideo.com
Ceramic,
Tantalum
Ceramic,
Polymer,
T494, T495
POSCAP
Tantalum
Murata
AVX
Taiyo Yuden
(404) 436-1300
(864) 963-6300
www.murata.com
www.avxcorp.com
www.taiyo-yuden.com
Ceramic
Ceramic,
Tantalum
Ceramic
TPS Series
capacitor must be large to achieve low ESR. Table 2 lists
several capacitor vendors.
Figure 4 shows the transient response of the LT3493 with
several output capacitor choices. The output is 3.3V. The
load current is stepped from 250mA to 1A and back to
250mA, and the oscilloscope traces show the output volt-
age. The upper photo shows the recommended value. The
second photo shows the improved response (less voltage
drop) resulting from a larger output capacitor and a phase
lead capacitor. The last photo shows the response to a high
performance electrolytic capacitor. Transient performance
is improved due to the large output capacitance.
BOOST Pin Considerations
Capacitor C3 and diode D2 are used to generate a boost
voltage that is higher than the input voltage. In most cases
a 0.1μF capacitor and fast switching diode (such as the
1N4148 or 1N914) will work well. Figure 5 shows two
ways to arrange the boost circuit. The BOOST pin must
be at least 2.3V above the SW pin for best ef?ciency. For
outputs of 3.3V and above, the standard circuit (Figure 5a)
is best. For outputs between 3V and 3.3V, use a 0.22μF
capacitor. For outputs between 2.5V and 3V, use a 0.47μF
capacitor and a small Schottky diode (such as the BAT-
54). For lower output voltages the boost diode can be tied
ef?cient because the BOOST pin current comes from a lower
voltage source. You must also be sure that the maximum
voltage rating of the BOOST pin is not exceeded.
The minimum operating voltage of an LT3493 applica-
tion is limited by the undervoltage lockout (3.6V) and by
the maximum duty cycle as outlined above. For proper
start-up, the minimum input voltage is also limited by
the boost circuit. If the input voltage is ramped slowly,
or the LT3493 is turned on with its SHDN pin when the
output is already in regulation, then the boost capacitor
may not be fully charged. Because the boost capacitor is
charged with the energy stored in the inductor, the circuit
will rely on some minimum load current to get the boost
circuit running properly. This minimum load will depend
on the input and output voltages, and on the arrangement
of the boost circuit. The minimum load generally goes to
zero once the circuit has started. Figure 6 shows a plot of
minimum load to start and to run as a function of input
voltage. In many cases the discharged output capacitor
will present a load to the switcher which will allow it to
start. The plots show the worst-case situation where V IN
is ramping verly slowly. For lower start-up voltage, the
boost diode can be tied to V IN ; however this restricts the
input range to one-half of the absolute maximum rating
of the BOOST pin.
to the input (Figure 5b). The circuit in Figure 5a is more
3493fb
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3493IDCB-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.2A, 750kHz Step-Down Switching Regulator in 2mm × 3mm DFN |
| LT3494 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Low Noise Boost Converters with Output Disconnect |
| LT3494A | 制造商:LINER 制造商全称:Linear Technology 功能描述:20mA LED Driver and OLED Driver with Integrated Schottky in 3mm x 2mm DFN |
| LT3494AEDDB | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Low Noise Boost Converters with Output Disconnect |
| LT3494AEDDB#PBF | 制造商:Linear Technology 功能描述:BOOST 2.3 - 16V 0.35A 40V 制造商:Linear Technology 功能描述:BOOST, 2.3 - 16V, 0.35A, 40V, 20QFN |
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