參數(shù)資料
型號(hào)： LT3724IFE
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS
中文描述： 0.3 A SWITCHING CONTROLLER, 220 kHz SWITCHING FREQ-MAX, PDSO16
封裝： 4.4 MM, PLASTIC, TSSOP-16
文件頁(yè)數(shù)： 17/24頁(yè)
文件大?。?/td> 240K
代理商： LT3724IFE
LT3724
17
3724f
Inductor current typically doesn’t reach I
MAX
in the few
cycles that occur before soft-start becomes active, but can
with high input voltages or small inductors, so the above
relation is useful as a worst-case scenario.
This energy transfer increase in output voltage is typically
small, but for some low voltage applications with relatively
small output capacitors, it can become significant. The
voltage rise can be reduced by increasing output capaci-
tance, which puts additional limitations on C
OUT
for these
low voltage supplies. Another approach is to add an
external current limit foldback circuit which reduces the
value of I
MAX
during start-up.
An external current limit foldback circuit can be easily
incorporated into an LT3724 DC/DC converter application
by placing a 1N4148 diode and a 47k
resistor from the
converter output (V
OUT
) to the LT3724’s V
C
pin. This limits
the peak current to 0.25 I
MAX
when V
OUT
= 0V. A current
limit foldback circuit also has the added advantage of
providing reduced output current in the DC/DC converter
during short-circuit fault conditions, so a foldback circuit
may be useful even if the soft-start function is disabled.
If the soft-start circuit is disabled by shorting the C
SS
pin
to ground, the external current limit foldback circuit must
be modified by adding an additional diode and resistor.
The 2-diode, 2-resistor network shown also provides 0.25
I
MAX
when V
OUT
= 0V.
Efficiency Considerations
The efficiency of a switching regulator is equal to the
output power divided by the input power times 100%.
Express percent efficiency as:
% Efficiency = 100% - (L1 + L2 + L3 + ...)
where L1, L2, etc. are individual loss terms as a percentage
of input power.
Although all dissipative elements in the circuit produce
losses, four main contributors usually account for most of
the losses in LT3724 circuits:
1. LT3724 V
IN
and V
CC
current loss
2. I
2
R conduction losses
3. MOSFET transition loss
4. Schottky diode conduction loss
1. The V
IN
and V
CC
currents are the sum of the quiescent
currents of the LT3724 and the MOSFET drive currents.
The quiescent currents are in the LT3724 Electrical Char-
acteristics table. The MOSFET drive current is a result of
charging the gate capacitance of the power MOSFET each
cycle with a packet of charge, Q
G
. Q
G
is found in the
MOSFET data sheet. The average charging current is
calculated as Q
G
f
SW
. The power loss term due to these
currents can be reduced by backdriving V
CC
with a lower
voltage than V
IN
such as V
OUT
.
APPLICATIOU
W
U
U
Figure 7. Current Limit Foldback Circuit
for Applications that use Soft-Start
Figure 8. Current Limit Foldback Circuit for Applications
that have Soft-Start Disabled (C
SS
Pin Shorted to SGND)
1N4148
47k
V
OUT
V
C
3724 F03
1N4148
27k
39k
V
OUT
V
C
3724 F07
1N4148
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT3724IFE#PBF 功能描述:IC REG CTRLR BST INV PWM 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,000 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 包裝:帶卷 (TR)
LT3724IFE#PBF 制造商:Linear Technology 功能描述:DC-DC CONVERTER BUCK 200KHZ 制造商:Linear Technology 功能描述:DC-DC CONVERTER, BUCK, 200KHZ, TSSOP-16
LT3724IFE#TRPBF 功能描述:IC REG CTRLR BST INV PWM 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX
LT3724IFE-PBF 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Voltage, Current Mode Switching Regulator Controller
LT3724IFE-TRPBF 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Voltage, Current Mode Switching Regulator Controller
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