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参数资料
| 型号： | LT3513EUHF#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 3.5 A SWITCHING REGULATOR, 2220 kHz SWITCHING FREQ-MAX, PQCC38 |
| 封装： | 5 X 7 MM, LEAD FREE, PLASTIC, MO-220WHKD, QFN-38 |
| 文件页数： | 4/22页 |
| 文件大小： | 374K |
| 代理商： | LT3513EUHF#TRPBF |
LT3513
12
3513fc
operaTion
A power good comparator monitors AVDD and turns on
when FB2 is at or above 90% of its regulated value. The
output is an open-collector transistor that is off when the
output is out of regulation, allowing an external resistor
to pull the pin high. This pin can be used with a P-channel
MOSFET that functions as an output disconnect for AVDD.
The four switchers are current mode regulators. Instead
of directly modulating the duty cycle of the power switch,
the feedback loop controls the peak current in the switch
duringeachcycle.Comparedtovoltagemodecontrol,cur-
rent mode control improves loop dynamics and provides
cycle-by-cycle current limit.
All four switchers employ a constant-frequency current
mode control scheme. Switcher 1, the step-down regula-
tor, differs slightly from the others with inductor current
sense. Instead of monitoring the current at the switch,
current nodes are used to measure the current through
the inductor. Inductor current sense does not suffer from
minimum on-time problems, therefore always keep-
ing the switch current limited with any input-to-output
voltage ratio. Switcher 1 is always synchronized to the
master oscillator. The other three switchers each have
their own slave oscillator. The slave oscillator reduces the
frequency when the feedback voltage dips below 0.75V
and decreases linearly below the threshold as shown in
thePerformanceCharacteristics’FrequencyFoldbackplot.
Otherthanthesetwodifferences,thecontrolloopissimilar
in all four switchers. A pulse from the master oscillator
for switcher 1 or a pulse from the slave oscillator for the
other three switchers sets the RS latch and turns on the
internal NPN bipolar power switch. Current in the switch
and the external inductor begins to increase. When this
currentexceedsaleveldeterminedbythevoltageatVC,the
current comparator resets the latch, turning off the switch.
The current in the inductor flows through the Schottky
diode and begins to decrease. The cycle begins again at
the next pulse from the oscillator. In this way, the voltage
on the VC pin controls the current through the inductor to
theoutput.Theinternalerroramplifierregulatestheoutput
by continually adjusting the VC pin voltage. The threshold
for switching on the VC pin is 0.8V, and an active clamp
of 1.8V limits the VC voltage. Switchers 2, 3 and 4 also
contain an independent current limit not dependent on VC
or duty cycle. Switcher 1’s current limit is controlled by
the VC voltage and varies with duty cycle. All four switch-
ers also use slope compensation to ensure stability with
the current mode scheme at duty cycles above 50%. The
RUN-SS1, RUN-SS2 and RUN-SS3/4 pins control the rate
of rise of the feedback pins.
The switch driver for SW1 operates either from VINorfrom
the BOOST pin. An external capacitor and an integrated
SchottkydiodeareusedtogenerateavoltageattheBOOST
pin that is higher than the input supply. This allows the
driver to saturate the internal bipolar NPN power switch
for efficient operation.
INPUT VOLTAGE RANGE STEP-DOWN CONSIDERATION
Theminimumoperatingvoltageofswitcher1isdetermined
either by the LT3513’s undervoltage lockout of ~4V or by
its maximum duty cycle. A user defined undervoltage
lockout may be set with the UVLO pin at a voltage higher
than the internal undervoltage lockout. The duty cycle is
the fraction of time that the internal switch is on and is
determined by the input and output voltages:
Dc
=
VOUT + VF
VIN – VSW + VF
where VF is the forward voltage drop of the catch diode
(~0.4V) and VSW is the voltage drop of the internal switch
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PDF描述 |
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| LT3513EUHF#PBF | 3.5 A SWITCHING REGULATOR, 2220 kHz SWITCHING FREQ-MAX, PQCC38 |
| LT3513IUHF#TRPBF | 3.5 A SWITCHING REGULATOR, 2220 kHz SWITCHING FREQ-MAX, PQCC38 |
| LT3573EMSE#TRPBF | 1.85 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
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相关代理商/技术参数 |
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| LT3513IUHF#PBF | 功能描述:IC REG 5-OUT FOR TFT-LCD 38QFN 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 |
| LT3513IUHF#TRPBF | 功能描述:IC REG 5-OUT FOR TFT-LCD 38QFN 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 |
| LT3513IUHF-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:2MHz High Current 5-Output Regulator for TFT-LCD Panels |
| LT3513IUHF-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:2MHz High Current 5-Output Regulator for TFT-LCD Panels |
| LT3514EFE#PBF | 制造商:Linear Technology 功能描述:IC REG BUCK ADJ 24-TSSOP 制造商:Linear Technology 功能描述:BUCK 350KHZ-2.2MHZ 3.2-36V 制造商:Linear Technology 功能描述:BUCK, 350KHZ-2.2MHZ, 3.2-36V, TSSOP-24 制造商:Linear Technology 功能描述:DC-DC CONV, BUCK, ADJ, 2.1MHZ, TSSOP-24, Primary Input Voltage:36V, No. of Outputs:3, Output Current:2A, No. of Pins:24, Operating Temperature Min:-40C, Operating Temperature Max:125C, MSL:MSL 1 - Unlimited, Package / Case:24-TSSOP |
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