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參數(shù)資料
| 型號： | LTC1772BIS6#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1 A SWITCHING CONTROLLER, 650 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | LEAD FREE, PLASTIC, MO-193, SOT-23, 6 PIN |
| 文件頁數(shù)： | 14/16頁 |
| 文件大?。?/td> | 223K |
| 代理商： | LTC1772BIS6#PBF |
LTC1772B
7
1772bfa
OPERATION
that the external P-channel MOSFET will remain on for
more than one oscillator cycle since the inductor current
has not ramped up to the threshold set by EAMP. Further
reduction in input supply voltage will eventually cause the
P-channel MOSFET to be turned on 100%, i.e., DC. The
output voltage will then be determined by the input volt-
age minus the voltage drop across the MOSFET, the sense
resistor and the inductor.
Undervoltage Lockout
To prevent operation of the P-channel MOSFET below safe
input voltage levels, an undervoltage lockout is incorpo-
rated into the LTC1772B. When the input supply voltage
drops below approximately 2.0V, the P-channel MOSFET
and all circuitry is turned off except the undervoltage block,
which draws only several microamperes.
Short-Circuit Protection
When the output is shorted to ground, the frequency of
the oscillator will be reduced to about 120kHz. This lower
frequency allows the inductor current to safely discharge,
thereby preventing current runaway. The oscillator’s fre-
quency will gradually increase to its designed rate when
the feedback voltage again approaches 0.8V.
Overvoltage Protection
As a further protection, the overvoltage comparator in
the LTC1772B will turn the external MOSFET off when
the feedback voltage has risen 7.5% above the reference
voltage of 0.8V. This comparator has a typical hysteresis
of 20mV.
Slope Compensation and Inductor’s Peak Current
The inductor’s peak current is determined by:
I
V
R
PK
ITH
SENSE
=
()
–.
085
10
when the LTC1772B is operating below 40% duty
cycle. However, once the duty cycle exceeds 40%, slope
compensation begins and effectively reduces the peak
inductor current. The amount of reduction is given by the
curves in Figure 3.
Figure 3. Maximum Output Current vs Duty Cycle
DUTY CYCLE (%)
110
100
90
80
70
60
50
40
30
20
10
SF
=
I
OUT
/I
OUT(MAX)
(%)
1772 F03
0
70 80 90 100
60
10
20 30
40 50
IRIPPLE = 0.4IPK
AT 5% DUTY CYCLE
IRIPPLE = 0.2IPK
AT 5% DUTY CYCLE
VIN = 4.2V
(Refer to Functional Diagram)
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相關代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1772CS6 | 制造商:Linear Technology 功能描述:Swithed-Mode Power Supply Controller, Current Mode Type, 3 Pin, Plastic, TO-236 |
| LTC1772CS6#PBF | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 2.5V to 9.8V Input 6-Pin TSOT-23 制造商:Linear Technology 功能描述:BUCK 2.8 - 20V 5A 1.23-18V 6SOT23 制造商:Linear Technology 功能描述:BUCK, 2.8 - 20V, 5A, 1.23-18V, 6SOT23 |
| LTC1772CS6#TR | 功能描述:IC REG CTRLR BUCK PWM CM SOT23-6 RoHS:否 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:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1772CS6#TRM | 功能描述:IC REG CTRLR BUCK PWM CM SOT23-6 RoHS:否 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:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1772CS6#TRMPBF | 功能描述:IC REG CTRLR BUCK PWM CM SOT23-6 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:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
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