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参数资料
| 型号： | LTC1430CS#TR |
| 厂商： | Linear Technology |
| 文件页数： | 12/16页 |
| 文件大小： | 0K |
| 描述： | IC SW REG CNTRLR STEP-DWN 16SOIC |
| 标准包装： | 2,500 |
| 应用： | 控制器，Intel Pentium? |
| 输入电压： | 4 V ~ 8 V |
| 输出数： | 1 |
| 输出电压： | 3.3V，可调 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SOIC |
| 包装： | 带卷 (TR) |
LTC1430
A PPLICATI
S I FOR ATIO
causing the voltage at SS to fall. As SS falls, it will limit the
output duty cycle, limiting the current at the output.
Eventually the system will reach equilibrium, where the
pull-up current at the SS pin matches the pull-down
current in the I LIM amplifier; the LTC1430 will stay in this
state until the overcurrent condition disappears. At this
time I FB will rise, I LIM will stop sinking current and the
internal pull-up will recharge the soft-start capacitor,
restoring normal operation. Note that the I FB pin requires
an external 1k series resistor to prevent voltage transients
at the drain of M2 from damaging internal structures.
The I LIM amplifier pulls current out of SS in proportion to
the difference between I FB and I MAX . Under mild overload
conditions, the SS pin will fall gradually, creating a time
delay before current limit takes effect. Very short, mild
overloads may not trip the current limit circuit at all.
Longer overload conditions will allow the SS pin to reach
a steady level, and the output will remain at a reduced
voltage until the overload is removed. Serious overloads
will generate a larger overdrive at I LIM , allowing it to pull SS
down more quickly and preventing damage to the output
components.
The I LIM amplifier output is disabled when M1 is OFF to
prevent the low I FB voltage in this condition from activating
the current limit. It is re-enabled a fixed 170ns after M1
turns on; this allows for the I FB node to slew back high and
the I LIM amplifier to settle to the correct value. As the
LTC1430 goes deeper into current limit, it will reach a point
where the M1 on-time needs to be cut to below 170ns to
control the output current. This conflicts with the mini-
mum settling time needed for proper operation of the I LIM
amplifier. At this point, a secondary current limit circuit
begins to reduce the internal oscillator frequency, length-
ening the off-time of M1 while the on-time remains con-
stant at 170ns. This further reduces the duty cycle, allow-
ing the LTC1430 to maintain control over the output
current.
Under extreme output overloads or short circuits, the I LIM
amplifier will pull the SS pin more than 2V below V CC in a
single switching cycle, cutting the duty cycle to zero. At
this point all switching stops, the output current decays
through M2 and the LTC1430 runs a partial soft-start cycle
and restarts. If the short is still present the cycle will
repeat. Peak currents can be quite high in this condition,
but the average current is controlled and a properly
designed circuit can withstand short circuits indefinitely
with only moderate heat rise in the output FETs. In addi-
tion, the soft-start cycle repeat frequency can drop into the
low kHz range, causing vibrations in the inductor which
provide an audible alarm that something is wrong.
0.1 μ F
R IMAX
PV CC
COMP
LTC1430
FB
I MAX
I FB
1k
SS
V CC
12 μ A
12 μ A
V CC
+
I LIM
–
C SS
LTC1430 ? F09
SS
12 μ A
Figure 9. Soft-Start Clamps COMP Pin
C SS
LTC1430
LTC1430 ? F10
Figure 10. Current Limit Operation
12
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| LTC1430IS | 功能描述:IC SW REG CNTRLR STEP-DWN 16SOIC RoHS:否 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 |
| LTC1430IS#PBF | 功能描述:IC SW REG CNTRLR STEP-DWN 16SOIC 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 |
| LTC1430IS#TR | 功能描述:IC SW REG CNTRLR STEP-DWN 16SOIC RoHS:否 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 |
| LTC1430IS#TRPBF | 功能描述:IC SW REG CNTRLR STEP-DWN 16SOIC 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 |
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