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參數資料
| 型號： | LT1683IG |
| 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： | 20/24頁 |
| 文件大?。?/td> | 237K |
| 代理商： | LT1683IG |
20
LT1683
1683f
Solid Tantalum:Small size and low impedance. Typically
the maximum voltage rating is 50V. With large surge
currents the capacitor may need to be derated or you need
a special type such as AVX TPS line.
OS-CON:Lower impedance than aluminum but only avail-
able for 35V or less. Form factor may be a problem.
Ceramic:Generally used for high frequency and high
voltage bypass. They may resonate with their ESL before
ESR becomes dominant. Recent multilayer ceramic (MLC)
capacitors provide larger capacitance with low ESR.
There are continuous improvements being made in ca-
pacitors so consult with manufacturers as to your specific
needs.
Input Capacitors
The input capacitor should have low ESR at high frequen-
cies since this will be an important factor concerning how
much conducted noise is created.
There are two separate requirements for input capacitors.
The first is for supply to the part’s V
IN
pin. The V
IN
pin will
provide current for the part itself and the gate charge
current.
The worst component from an AC point is the gate charge
current. The actual peak current depends on gate capaci-
tance and slew rate, being higher for larger values of each.
The total current can be estimated by gate charge and
frequency of operation. Because of the slewing with this
part gate charge is spread out over a longer time period
than with a normal FET driver. This reduces capacitance
requirements.
Typically the current will have spikes of under 100mA
located at the gate voltage transitions. This is charge/
discharge to and from the threshold voltage. Most slewing
occurs with the gate voltage near threshold.
Since the part’s V
IN
will typically be under 15V many
options are available for choice of capacitor. Values of
input capacitor for just V
IN
requirement will typically be in
the 50
μ
F range with an ESR of under 0.1
.
In addition to the part supply, decoupling of the supply to
the transformer needs to be considered. If this is the same
supply as the V
IN
pin then that capacitor will need to be
increased. However, often with this part the transformer
supply will be a higher voltage and as such a separate
capacitor.
The transformer decoupling capacitor will see the switch
current as ripple.
The above switch current computation can be used to
estimate the capacity for these capacitors.
C
V
I
ESR
DC
f
IN
CAP
SW MAX
(
MIN
=
1
)
where
V
CAP
is the allowed sag on the input capacitor.
ESR is the equivalent series resistance for the cap. In
general allowed sag will be a few tenths of volts.
Output Filter Capacitor
The output capacitor is chosen both for capacity and ESR.
The capacity must supply the load current in the switch off
state. While slew control reduces higher frequency com-
ponents of the ripple current in the capacitor, the capacitor
ESR and the magnitude of the output ripple current
controls the fundamental component. ESR should also be
low to reduce capacitor dissipation.
The capacitance value can be computed by consideration
of desired load ripple, duty cycle and ESR.
C
V
I
ESR
DC
f
OUT
OUT
L MAX
(
MIN
=
1
)
APPLICATIU
W
U
U
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| LT1683IG#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:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數: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#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:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數: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#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:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數: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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