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參數(shù)資料
| 型號： | LT1683EG |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Ultralow Noise Push-Pull DC/DC Controller |
| 中文描述： | SWITCHING CONTROLLER, 250 kHz SWITCHING FREQ-MAX, PDSO20 |
| 封裝： | 5.30 MM, PLASTIC, SSOP-20 |
| 文件頁數(shù)： | 21/24頁 |
| 文件大?。?/td> | 237K |
| 代理商： | LT1683EG |
21
LT1683
1683f
MOSFET Selection
There is a wide variety of MOSFETs to choose from for this
part. The part will work with either normal threshold (3V to
4V) or logic level threshold devices (1V to 2V).
Select a voltage rating to insure under worst-case condi-
tions that the MOSFET will not break down. Next choose an
R
ON
sufficiently low to meet both the power dissipation
capabilities of the MOSFET package as well as overall
efficiency needs of the converter.
The LT1683 can handle a large range of gate charges.
However at very large charge stability may be affected.
The power dissipation in the MOSFET depends on several
factors. The primary element is I
2
R heating when the
device is on. In addition, power is dissipated when the
device is slewing. An estimate for power dissipation is:
P
V
I
I
I
V
R
I
I
V
f
I
R
DC
IN
SR
IN
ON
SR
ON
=
+
+
+
4
+
2
2
2
2
2
2
2
4
3
where I is the average current,
I is the ripple current in the
switch, I
SR
is the current slew rate, V
SR
is the voltage slew
rate, f is the oscillator frequency, DC is the duty cycle and
R
ON
is the MOSFET on-resistance.
Setting GCL Voltage
Setting the voltage on the GCL pin depends on what type
of MOSFET is used and the desired gate drive undervolt-
age lockout voltage.
First determine the maximum gate drive that you require.
Typically you will want it to be at least 2V greater than the
maximum threshold. Higher voltages will lower the on
resistance and increase efficiency. Be certain to check the
maximum allowed gate voltage. Often this is 20V but for
some logic threshold MOSFETs it is only 8V to 10V.
V
GCL
needs to be set approximately 0.2V above the desired
max gate threshold. In addition V
IN
needs to be at least
1.6V above the gate voltage.
The GCL pin can be tied to V
IN
which will result in a
maximum gate voltage of V
IN
– 1.6V.
This pin also controls undervoltage lockout of the gate
drives. The undervoltage lockout will prevent the MOSFETs
from switching until there is sufficient drive present.
If GCL is tied to a voltage source or Zener less than 6.8V,
the gate drivers will not turn on until V
IN
exceeds the GCL
voltage by 0.8V. For V
GCL
above 6.5V, the gate drives are
insured to be off for V
IN
< 7.3V and they will be turned on
by V
GCL
+ 0.8V.
If GCL is tied to V
IN
, the gate drivers are always on
(undervoltage lockout is disabled).
Approximately 50
μ
A of current can be sourced from this
pin if V
IN
> V
GCL
+ 0.8V. This could be used to bias a Zener.
The GCL pin has an internal 19V Zener to ground that will
provide a failsafe for maximum gate voltage.
As an example say we are using a Siliconix Si4480DY
which has R
DS(ON)
rated at 6V. To get 6V, V
GCL
needs to be
set to 6.2V and V
IN
needs to be at least 7.6V.
APPLICATIU
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| LT1683EG#PBF | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 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:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LT1683EG#TR | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:否 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 |
| LT1683EG#TRPBF | 功能描述:IC REG CTRLR PWM CM 20-SSOP 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 |
| LT1683IG | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:否 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 |
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