参数资料
| 型号： | LT3742EUF#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/26页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 24-QFN |
| 标准包装： | 91 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 560kHz |
| 占空比： | 100% |
| 电源电压： | 4 V ~ 30 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： | -40°C ~ 125°C |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1332 (CN2011-ZH PDF) |
LT3742
APPLICATIONS INFORMATION
? 8 ? f SW ? C OUT
R B = R A ? ? OUT – 1 ?
LT3742’s control loop. Output ripple can be estimated
with the following equation:
? 1 ?
V RIPPLE = Δ I L ? + ESR ?
?
where Δ I L is the inductor ripple current and f SW is the
switching frequency (500kHz). The ESR is so low for
ceramic capacitors that it can be left out of the above
calculation. The output voltage ripple will be highest at
maximum input voltage ( Δ I L increases with input voltage).
Table 3 shows several low-ESR capacitor manufacturers.
Table 3. Low ESR Surface Mount Capacitors
VENDOR TYPE SERIES
Taiyo Yuden Ceramic X5R, X7R
www.t-yuden.com
Murata Ceramic X5R, X7R
www.murata.com
Kemet Tantalum T491, T494, T495
www.kemet.com Ta Organic T520
Al Organic A700
Sanyo Ta or Al Organic POSCAP
www.sanyo.com
Panasonic Al Organic SP CAP
www.panasonic.com
TDK Ceramic X5R, X7R
www.tdk.com
Nippon Chemicon Ceramic X5R, X7R
www.chemi-con.co.jp
Setting Output Voltage
The output of a bipolar controller requires a minimum load
to prevent current sourced from the switch pin charging
the output capacitor above the desired output voltage.
This current, approximately 5mA, may be accounted for
in the feedback string or the user may choose to force a
minimum load in their application.
V OUT1
The output voltage for each controller is programmed
with a resistor divider between the output and the FB pin.
Always use 1% resistors (or better) for the best output
voltage accuracy. The value of R A should be 8k or less,
and the value of R1 should be chosen according to:
? V ?
? 0.8V ?
Output Short-Circuit Protection
Because the LT3742 constantly monitors the inductor cur-
rent, both devices inherently providing excellent output
short-circuit protection. The N-channel MOSFET is not
allowed to turn on unless the inductor current is below the
threshold of the current sense comparator. This guaran-
tees that the inductor current will not “run away” and the
controller will skip cycles until the inductor current has
dropped below the current sense threshold.
Loop Compensation
An external resistor and capacitor connected in series from
the V C pin to ground provides loop compensation for each
controller. Sometimes a second, smaller valued capacitor
is placed in parallel to filter switching frequency noise from
the V C pin. Loop compensation determines the stability
and transient performance of each controller.
A practical approach is to start with values of R C = 10k
and C C = 330pF, then tune the compensation network to
optimize the performance. When adjusting these values,
change only one value at a time (R C or C C ), then see how
the transient response is affected. The simplest way to
check loop stability is to apply a load current step while
observing the transient response at the output. Stability
should then be checked across all operating conditions,
including load current, input voltage, and temperature to
ensure a robust design.
V OUT2
R1B
LT3742
R2B
R1A
V FB1
V FB2
R2A
3742 F07
Figure 7. Setting Output Voltage with the FB Pin
3742fa
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3742EUF-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual, 2-Phase Step-Down Switching Controller |
| LT3743 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Current Synchronous Step-Down LED Driver with Three-State Control |
| LT3743_10 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Current Synchronous Step-Down LED Driver with Three-State Control |
| LT3743EFE#PBF | 功能描述:IC LED DVR HP CONST CURR 28TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:60 系列:- 恒定电流:- 恒定电压:- 拓扑:线性（LDO），PWM，升压（升压） 输出数:8 内部驱动器:是 类型 - 主要:背光 类型 - 次要:RGB，白色 LED 频率:500kHz ~ 1.5MHz 电源电压:4.75 V ~ 26 V 输出电压:45V 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* 工作温度:-40°C ~ 85°C |
| LT3743EFE#PBF | 制造商:Linear Technology 功能描述:IC LED DRIVER BUCK TSSOP-28 |
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