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| 型号： | LT3958EUHE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/28页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG ADJ 36VQFN |
| 特色产品： | LT?3957/LT?3958 Converters |
| 标准包装： | 61 |
| 类型： | 升压（升压），反相，回扫，Sepic |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.6 V ~ 80 V |
| 输入电压： | 5 V ~ 80 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz ~ 1MHz |
| 电流 - 输出： | 3.3A |
| 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： | 36-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 36-QFN-EP（6x5） |
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LT3958
APPLICATIONS INFORMATION
The Internal Power Switch Current
For control and protection, the LT3958 measures the
internal power MOSFET current by using a sense resistor
(R SENSE ) between GND and the MOSFET source. Figure 3
shows a typical waveform of the internal switch current
(I SW ).
I SW
I SW
I SW(PEAK)
On-Chip Power Dissipation and Thermal Lockout (TLO)
The on-chip power dissipation of LT3958 can be estimated
using the following equation:
P IC ≈ I 2SW ? D ? R DS(ON) + V 2SW(PEAK) ? I SW ? ? ? 200pF/A +
V IN ? (1.6mA + ? ? 10nC)
where R DS(ON) is the internal switch on-resistance which
can be obtained from the Typical Performance Characteris-
tics section. V SW(PEAK) is the peak switch off-state voltage.
The maximum power dissipation P IC(MAX) can be obtained
by comparing P IC across all the V IN range at the maximum
DT S
T S
t
output current . The highest junction temperature can be
estimated using the following equation:
3958 F03
Figure 3. The Switch Current During a Switching Cycle
Due to the current limit (minimum 3.3A) of the internal
power switch, the LT3958 should be used in the applica-
tions that the switch peak current I SW(PEAK) during steady
state normal operation is lower than 3.3A by a suf?cient
margin (10% or higher is recommended).
The LT3958 switching controller incorporates 100ns
timing interval to blank the ringing on the current sense
signal across R SENSE immediately after M1 is turned on.
This ringing is caused by the parasitic inductance and
capacitance of the PCB trace, the sense resistor, the diode,
T J(MAX) ≈ T A + P IC(MAX) ? 42°C/W
It is recommended to measure the IC temperature in steady
state to verify that the junction temperature limit is not
exceeded. A low switching frequency may be required to
ensure T J(MAX) does not exceed 125°C.
If LT3958 die temperature reaches thermal lockout
threshold at 165°C (typical), the IC will initiate several
protective actions. The power switch will be turned off.
A soft-start operation will be triggered. The IC will be en-
abled again when the junction temperature has dropped
by 5°C (nominal).
LT3958
and the MOSFET. The 100ns timing interval is adequate
for most of the LT3958 applications. In the applications
SENSE1
R FLT
that have very large and long ringing on the current sense
signal, a small RC ?lter can be added to ?lter out the excess
ringing. Figure 4 shows the RC ?lter on the SENSE1 and
SENSE2 pins. It is usually suf?cient to choose 22Ω for
R FLT and 2.2nF to 10nF for C FLT . Keep R FLT ’s resistance
low. Remember that there is 65μA (typical) ?owing out of
the SENSE2 pin. Adding R FLT will affect the internal power
switch current limit threshold:
SENSE2
C FLT
SGND
3958 F04
Figure 4. The RC Filter on SENSE1 Pin and SENSE2 Pin
I SW _ILIM = ? 1 ?
? ? ? 3.3A
?
?
65μA ? R FLT ?
48mV
3958f
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3958EUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Converter |
| LT3958IUHE#PBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3958IUHE#TRPBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3958IUHEPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Converter |
| LT3958IUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Input Voltage, Boost, Flyback, SEPIC and Inverting Converter |
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