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參數(shù)資料
| 型號： | 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 |
| 文件頁數(shù)： | 9/24頁 |
| 文件大小： | 240K |
| 代理商： | LT3724IFE |
LT3724
9
3724f
The LT3724 is a PWM controller with a constant fre-
quency, current mode control architecture. It is designed
for low to medium power, switching regulator applica-
tions. Its high operating voltage capability allows it to step-
up or down input voltages up to 60V without the need for
a transformer. The LT3724 is used in nonsynchronous
applications, meaning that a freewheeling rectifier diode
(D1 of Function Diagram) is used instead of a bottom side
MOSFET. For circuit operation, please refer to the Func-
tional Diagram of the IC and Typical Application on the
front page of the data sheet. The LT3800 is a similar part
that uses synchronous rectification, replacing the diode
with a MOSFET in a step-down application.
Main Control Loop
During normal operation, the external N-channel MOSFET
switch is turned on at the beginning of each cycle. The
switch stays on until the current in the inductor exceeds a
current threshold set by the DC control voltage, V
C
, which
is the output of the voltage control loop. The voltage
control loop monitors the output voltage, via the V
FB
pin
voltage, and compares it to an internal 1.231V reference.
It increases the current threshold when the V
FB
voltage is
below the reference voltage and decreases the current
threshold when the V
FB
voltage is above the reference
voltage. For instance, when an increase in the load current
occurs, the output voltage drops causing the V
FB
voltage
to drop relative to the 1.231V reference. The voltage
control loop senses the drop and increases the current
threshold. The peak inductor current is increased until the
average inductor current equals the new load current and
the output voltage returns to regulation.
Current Limit/Short-Circuit
The inductor current is measured with a series sense
resistor (see the Typical Application on the front page).
When the voltage across the sense resistor reaches the
maximum current sense threshold, typically 150mV, the
TG MOSFET driver is disabled for the remainder of that
cycle. If the maximum current sense threshold is still
exceeded at the beginning of the next cycle, the entire cycle
is skipped. Cycle skipping keeps the inductor currents to
a reasonable value during a short-circuit, particularly
when V
IN
is high. Setting the sense resistor value is
discussed in the “Application Information” section.
V
CC
/Boosted Supply
An internal V
CC
regulator provides V
IN
derived gate-drive
power for start-up under all operating conditions with
MOSFET gate charge loads up to 90nC. The regulator can
operate continuously in applications with V
IN
voltages up
to 60V, provided the V
IN
voltage and/or MOSFET gate
charge currents do not create excessive power dissipation
in the IC. Safe operating conditions for continuous regu-
lator use are shown in Figure 1. In applications where
these conditions are exceeded, V
CC
must be derived from
an external source after start-up. The LT3724 regulator
can, however, be used for “full time” use in applications
where short-duration V
IN
transients exceed allowable con-
tinuous voltages.
OPERATIOU
(Refer to Functional Diagram)
Figure 1. V
CC
Regulator Continuous Operating Conditions
For higher converter efficiency and less power dissipation
in the IC, V
CC
can also be supplied from an external supply
such as the converter output. When an external supply
back drives the internal V
CC
regulator through an external
diode and the V
CC
voltage is pulled to a diode above its
regulation voltage, the internal regulator is disabled and
goes into a low current mode. V
CC
is the bias supply for
most of the internal IC functions and is also used to charge
the bootstrapped capacitor (C
BOOST
) via an external diode.
The external MOSFET switch is biased from the
bootstrapped capacitor. While the external MOSFET switch
is off, an internal BJT switch, whose collector is connected
to the SW pin and emitter is connected to the PGND pin,
is turned on to pull the SW node to PGND and recharge the
bootstrap capacitor. The switch stays on until either the
MOSFET TOTAL GATE CHARGE (nC)
0
V
I
(
70
60
50
40
30
20
10
20
40
60
80
3724 F01
100
SAFE
OPERATING
AREA
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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:- 標準包裝: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:- 標準包裝: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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