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參數(shù)資料
| 型號(hào)： | ISL6741 |
| 廠商： | Intersil Corporation |
| 英文描述： | Flexible Double-Ended Voltage and Current Mode PWM Controllers |
| 中文描述： | 靈活的雙端電壓和電流模式PWM控制器 |
| 文件頁數(shù)： | 11/21頁 |
| 文件大?。?/td> | 507K |
| 代理商： | ISL6741 |
11
As V
IN
decreases to a UV condition, the threshold level is:
The hysteresis voltage,
V, is:
Setting R3 equal to zero results in the minimum hysteresis,
and yields:
As V
IN
increases from a UV condition, the threshold level is:
Over Current Operation
ISL6740 -
Over current delayed shutdown is enabled once
the soft start cycle is complete. If an over current condition is
detected, the soft start charging current source is disabled
and the soft start capacitor is allowed to discharge through a
15
μ
A source. At the same time a 50
μ
s re-triggerable one-
shot timer is activated. It remains active for 50
μ
s after the
over current condition ceases. If the soft start capacitor
discharges by more then 0.25V to 4.25V, the output is
disabled and the Fault signal asserted. This state continues
until the soft start voltage reaches 270mV, at which time a
new soft start cycle is initiated. If the over current condition
stops at least 50
μ
s prior to the soft start voltage reaching
4.25V, the soft start charging currents revert to normal
operation and the soft start voltage is allowed to recover.
ISL6741 -
Over current results in pulse-by-pulse duty cycle
reduction as occurs in any peak current mode controller.
This results in a well controlled decrease in output voltage
with increasing current beyond the over current threshold.
An over current condition in the ISL6741 will not cause a
shutdown.
Short Circuit Operation
A short circuit condition is defined as the simultaneous
occurrence of current limit and a reduced duty cycle. The
degree of reduced duty cycle is user adjustable using the
SCSET input. A resistor divider between either R
TD
or R
TC
and GND to RCSET sets a threshold that is compared to the
voltage on the timing capacitor, C
T
. The resistor divider
percentage corresponds to the maximum duty cycle
percentage below which a short circuit may exist. If the
timing capacitor voltage fails to exceed the threshold before
an over current pulse is detected, a short circuit condition
exists. A shutdown and soft start cycle will begin if 8 short
circuit events occur within 32 oscillator cycles.
Since the current sourced from both R
TC
and R
TD
determine the charge and discharge currents for the timing
capacitor, the effect of the SCSET divider must be included
in the timing calculations. Typically the resistor between R
TC
and GND is formed by two series resistors with the center
node connected to SCSET.
Alternatively, SCSET may be set using a voltage between
0V and 2V. This voltage divided by 2 determines the
percentage of the maximum duty cycle that corresponds to a
short circuit when current limit is active. For example, if the
maximum duty cycle is 95% and 1V is applied to SCSET,
then the short circuit duty cycle is 50% of 95% or 47.5%.
Fault Conditions
A Fault condition occurs if V
REF
falls below 4.65V, the UV
input falls below 1.00V, or the thermal protection is triggered
(internal or external). When a Fault is detected, OUTA and
OUTB outputs are disabled, the Fault signal is asserted, and
the soft start capacitor is quickly discharged. When the Fault
condition clears and the soft start voltage is below the reset
threshold, a soft start cycle begins.
An over current condition that results in shutdown (ISL6740),
or a short circuit condition also cause assertion of the Fault
signal. The difference between a current fault and the faults
described earlier is that the soft start capacitor is not quickly
discharged. The initiation of a new soft start cycle is delayed
while the soft start capacitor is discharged at a 15
μ
A rate.
This keeps the average output current to a minimum.
Thermal Protection
Two methods of over temperature protection are provided.
The first method is an on board temperature sensor that
protects the device should the junction temperature exceed
145
°
C. There is approximately 15
°
C of hysteresis.
The second method uses an internal comparator with a 2.5V
reference (V
REF
/2). The non-inverting input to the
comparator is accessible through the OTS pin. A thermistor
or thermal sensor located at or near the area of interest may
be connected to this input. There is a nominal 25
μ
A switched
current source used to create hysteresis. The current source
is active only during an OT fault; otherwise, it is inactive and
FIGURE 5. UV HYSTERESIS
V
IN
R1
R2
R3
1.00V
10
μ
A
ON
+
-
V
IN DOWN
(
)
--------+
=
V
(EQ. 7)
V
10
5
–
R1
R3
--------+
+
=
V
(EQ. 8)
V
10
5
–
R1
=
V
(EQ. 9)
V
IN UP
(
)
V
IN DOWN
(
)
V
+
=
V
(EQ. 10)
ISL6740, ISL6741
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL6741IB | 功能描述:電流型 PWM 控制器 CUR PWM MODE CNTRLR 16LD N RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| ISL6741IB-T | 功能描述:IC REG CTRLR PWM CM 16-SOIC 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:100% 電源電壓:8.2 V ~ 30 V 降壓:無 升壓:無 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:0°C ~ 70°C 封裝/外殼:8-DIP（0.300"，7.62mm） 包裝:管件 產(chǎn)品目錄頁面:1316 (CN2011-ZH PDF) |
| ISL6741IBZ | 功能描述:IC REG CTRLR PWM CM 16-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 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:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6741IBZ-T | 功能描述:IC REG CTRLR PWM CM 16-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 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:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6741IV | 功能描述:IC REG CTRLR PWM CM 16-TSSOP 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:100% 電源電壓:8.2 V ~ 30 V 降壓:無 升壓:無 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:0°C ~ 70°C 封裝/外殼:8-DIP（0.300"，7.62mm） 包裝:管件 產(chǎn)品目錄頁面:1316 (CN2011-ZH PDF) |
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