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參數(shù)資料
| 型號： | LTC3714EG |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Intel Compatible, Wide Operating Range, Step-Down Controller with Internal Op Amp |
| 中文描述： | 2 A SWITCHING CONTROLLER, PDSO28 |
| 封裝： | 5.30 MM, PLASTIC, SSOP-28 |
| 文件頁數(shù)： | 19/28頁 |
| 文件大?。?/td> | 345K |
| 代理商： | LTC3714EG |
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LTC3714
19
3714f
APPLICATIOU
Soft-Start and Latchoff with the RUN/SS Pin
The RUN/SS pin provides a means to shut down the
LTC3714 as well as a timer for soft-start and overcurrent
latchoff. Pulling the RUN/SS pin below 1.5V puts the
LTC3714 into a low quiescent current shutdown (I
Q
≤
30
μ
A). Releasing the pin allows an internal 1.2
μ
A internal
current source to charge up the external timing capacitor
C
SS
. If RUN/SS has been pulled all the way to ground, there
is a delay before starting of about:
W
U
U
t
V
AC
μ
s F C
1 3
.
/
DELAY
SS
SS
=
=
(
)
1 5
1 2
.
.
When the voltage on RUN/SS reaches 1.5V, the LTC3714
begins operating with a clamp on I
TH
of approximately
0.9V. As the RUN/SS voltage rises to 3V, the clamp on I
TH
is raised until its full 2.4V range is available. This takes an
additional 1.3s/
μ
F, during which the load current is folded
back until the output reaches 50% of its final value. The pin
can be driven from logic as shown in Figure 7. Diode D1
reduces the start delay while allowing C
SS
to charge up
slowly for the soft-start function.
After the controller has been started and given adequate
time to charge up the output capacitor, C
SS
is used as a
short-circuit timer. After the RUN/SS pin charges above
4V, if the output voltage falls below 75% of its regulated
value, then a short-circuit fault is assumed. A 1.7
μ
A cur-
rent then begins discharging C
SS
. If the fault condition
persists until the RUN/SS pin drops to 3.5V, then the con-
troller turns off both power MOSFETs, shutting down the
converter permanently. The RUN/SS pin must be actively
pulled down to ground in order to restart operation.
The overcurrent protection timer requires that the soft-
start timing capacitor C
SS
be made large enough to guar-
antee that the output is in regulation by the time C
SS
has
reached the 4V threshold. In general, this will depend upon
the size of the output capacitance, output voltage and load
current characteristic. A minimum soft-start capacitor can
be estimated from:
C
SS
> C
OUT
V
OUT
R
SENSE
(10
–4
[F/Vs])
Generally 0.1
μ
F is more than sufficient.
Overcurrent latchoff operation is not always needed or
desired. Load current is already limited during a short-
circuit by the current foldback circuitry and latchoff
operation can prove annoying during troubleshooting.
The feature can be overridden by adding a pull-up current
of >5
μ
A to the RUN/SS pin. The additional current pre-
vents the discharge of C
SS
during a fault and also shortens
the soft-start period. Using a resistor to V
IN
as shown in
Figure 7a is simple, but slightly increases shutdown
current. Connecting a resistor to INTV
CC
as shown in
Figure 7b eliminates the additional shutdown current, but
requires a diode to isolate C
SS
. Any pull-up network must
be able to pull RUN/SS above the 4.5V maximum thresh-
old that arms the latchoff circuit and overcome the 4
μ
A
maximum discharge current.
3.3V OR 5V
RUN/SS
V
IN
INTV
CC
RUN/SS
D1
(7a)
(7b)
D2*
C
SS
R
SS
*
C
SS
*OPTIONAL TO OVERRIDE
OVERCURRENT LATCHOFF
R
SS
*
3714 F07
Figure 7. RUN/SS Pin Interfacing with Latchoff Defeated
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相關(guān)代理商/技術(shù)參數(shù) |
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| LTC3714EG#PBF | 功能描述:IC STP-DWN CNTRLR W/OPAMP 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:控制器，DSP 輸入電壓:4.5 V ~ 25 V 輸出數(shù):2 輸出電壓:最低可調(diào)至 1.2V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:30-TFSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:30-TSSOP 包裝:帶卷 (TR) |
| LTC3714EG#PBF | 制造商:Linear Technology 功能描述:DC/DC CONVERTER IC |
| LTC3714EG#TR | 功能描述:IC STP-DWN CNTRLR W/OPAMP 28SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3714EG#TRPBF | 功能描述:IC STP-DWN CNTRLR W/OPAMP 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3716EG | 功能描述:IC REG CTRLR BUCK PWM CM 36-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: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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