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参数资料
| 型号： | LT3800EFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR INV PWM CM 16-TSSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 220kHz |
| 占空比： | 95% |
| 电源电压： | 4 V ~ 60 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 是 |
| 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： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 带卷 (TR) |
LT3800
APPLICATIONS INFORMATION
With the reverse-current inhibit feature enabled, an LT3800
converter will operate much like a nonsynchronous
responds to 2μA average current during the soft-start
interval. This capacitor value follows the relation:
converter during light loads. Reverse-current inhibit
reduces resistive losses associated with inductor ripple
currents, which improves operating ef?ciencies during
C SS1 =
2E –6 ? t SS
V OUT
light-load conditions.
An LT3800 DC/DC converter that is operating in reverse-
R SS is typically set to 200k for most applications.
inhibit mode has a minimum load requirement of 1mA
(BURST_EN = V FB ). Since most applications use output-
V OUT
C SS1
A
R SS
C SS
LT3800
generated power for the LT3800, this requirement is met
R SS =
by the bias currents of the IC, however, for applications
that do not derive power from the output, this require-
ment is easily accomplished by using a 1.2k resistor
connected from V FB to ground as one of the converter
output voltage programming resistors (R1). There are no
minimum load restrictions when in Burst Mode operation
(BURST_EN < 0.5V) or continuous conduction mode
(BURST_EN > 2.5V).
Soft-Start
The LT3800 incorporates a programmable soft-start
function to control start-up surge currents, limit output
overshoot and for use in supply sequencing. The soft-start
function directly monitors and controls output voltage slew
rate during converter start-up.
As the output voltage of the converter rises, the soft-start
circuit monitors δ V/ δ t current through a coupling capaci-
tor and adjusts the voltage on the V C pin to maintain an
average value of 2μA. The soft-start function forces the
programmed slew rate while the converter output rises to
95% regulation, which corresponds to 1.185V on the V FB
pin. Once 95% regulation is achieved, the soft-start circuit
is disabled. The soft-start circuit will re-enable when the
V FB pin drops below 70% regulation, which corresponds to
300mV of control hysteresis on the V FB pin, which allows
for a controlled recovery from a ‘brown-out’ condition.
The desired soft-start rise time (t SS ) is programmed via
a programming capacitor C SS1 , using a value that cor-
3800 AI06
Considerations for Low Voltage Output Applications
The LT3800 C SS pin biases to 220mV during the soft-start
cycle, and this voltage is increased at network node “A” by
the 2μA signal current through R SS , so the output has to
reach this value before the soft-start function is engaged.
The value of this output soft-start start-up voltage offset
(V OUT(SS) ) follows the relation:
V OUT(SS) = 220mV + R SS ? 2E –6
which is typically 0.64V for R SS = 200k.
In some low voltage output applications, it may be desir-
able to reduce the value of this soft-start start-up voltage
offset. This is possible by reducing the value of R SS . With
reduced values of R SS , the signal component caused by
voltage ripple on the output must be minimized for proper
soft-start operation.
Peak-to-peak output voltage ripple ( ? V OUT ) will be imposed
on node “A” through the capacitor C SS1 . The value of R SS
can be set using the following equation:
V OUT
1.3E –6
It is important to use low ESR output capacitors for LT3800
voltage converter designs to minimize this ripple voltage
component. A design with an excessive ripple component
can be evidenced by observing the V C pin during the start
cycle.
3800fc
11
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相关代理商/技术参数 |
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| LT3800IFE | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 60V 16-Pin TSSOP EP |
| LT3800IFE#PBF | 功能描述:IC REG CTRLR INV PWM CM 16-TSSOP 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 |
| LT3800IFE#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN REGULATOR CTRL 16-TSSO |
| LT3800IFE#TR | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 60V 16-Pin TSSOP EP T/R |
| LT3800IFE#TRPBF | 功能描述:IC REG CTRLR INV PWM CM 16-TSSOP 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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