- 您现在的位置：买卖IC网 > PDF目录176104 > ISL6741IBZ (INTERSIL CORP) Flexible Double Ended Voltage and Current Mode PWM Controllers PDF资料下载
参数资料
| 型号： | ISL6741IBZ |
| 厂商： | INTERSIL CORP |
| 元件分类： | 稳压器 |
| 英文描述： | Flexible Double Ended Voltage and Current Mode PWM Controllers |
| 中文描述： | 0.5 A SWITCHING CONTROLLER, 2000 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | ROHS COMPLIANT, PLASTIC, MS-012-AC, SOIC-16 |
| 文件页数： | 5/29页 |
| 文件大小： | 635K |
| 代理商： | ISL6741IBZ |
第1页第2页第3页第4页当前第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页
13
FN9111.4
July 13, 2007
The voltage hysteresis created by the switched current
source and the external impedance is generally small due to
the large resistor divider ratio required to scale the input
voltage down to the UV threshold level. A small capacitor
placed between the UV input and ground may be required to
filter noise out.
As VIN decreases to a UV condition, the threshold level is:
The hysteresis voltage,
ΔV, is:
Setting R3 equal to zero results in the minimum hysteresis,
and yields:
As VIN increases from a UV condition, the threshold level is:
Over Current Operation
ISL6740 - Overcurrent delayed shutdown is enabled once
the soft-start cycle is complete. If an overcurrent condition is
detected, the soft-start charging current source is disabled
and the soft-start capacitor is allowed to discharge through a
15
μA source. At the same time a 50μs re-triggerable one-
shot timer is activated. It remains active for 50
μs after the
overcurrent 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 overcurrent condition
stops at least 50
μs 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.
The duration of the OC shutdown period can be increased
by adding a resistor between VREF and SS. The value of
the resistor must be large enough so that the minimum
specified SS discharge current is not exceeded. Using a
422k
Ω resistor, for example, will result in a small current
being injected into SS, effectively reducing the discharge
current. This will increase the OFF time by about 60%,
nominally. The external pull-up resistor will also decrease
the SS duration, so its effect should be considered when
selecting the value of the SS capacitor.
Latching OC shutdown is also possible by using a lower
valued resistor between VREF and SS. If the SS node is not
allowed to discharge below the SS reset threshold, the IC
will not recover from an overcurrent fault. The value of the
resistor must be low enough so that the maximum specified
discharge current is not sufficient to pull SS below 0.33V. A
200k
Ω resistor, for example, prevents SS from discharging
below ~0.4V. Again, the external pull-up resistor will
decrease the SS duration, so its effect should be considered
when selecting the value of the SS capacitor.
ISL6741 - Overcurrent 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 overcurrent threshold. An
overcurrent 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 RTD or RTC
and GND to RCSET sets a threshold that is compared to the
voltage on the timing capacitor, CT. The resistor divider
percentage corresponds to the fraction of the maximum duty
cycle below which a short circuit may exist. If the timing
capacitor voltage fails to exceed the threshold before an
overcurrent 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. Connecting SCSET
to GND disables this feature.
Since the current sourced from both RTC and RTD 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 RTC 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%.
FIGURE 5. UV HYSTERESIS
VIN
R1
R2
R3
1.00V
10
μA
ON
+
-
V
IN DOWN
()
R1
R2
+
R2
----------------------
=
V
(EQ. 7)
ΔV10
5
–
R1
R3
R1
R2
+
R2
----------------------
+
=
V
(EQ. 8)
ΔV10
5
–
R1
=
V
(EQ. 9)
V
IN UP
()
V
IN DOWN
()
ΔV
+
=
V
(EQ. 10)
ISL6740, 1SL6741
相关PDF资料 |
PDF描述 |
|---|---|
| ISL6741IVZ | Flexible Double Ended Voltage and Current Mode PWM Controllers |
| ISL81487EIB-T | 【15kV ESD Protected, 1/8 Unit Load, 5V, Low Power, High Speed or Slew Rate Limited, RS-485/RS-422 Transceivers |
| ISL81487EIBZ-T | 【15kV ESD Protected, 1/8 Unit Load, 5V, Low Power, High Speed or Slew Rate Limited, RS-485/RS-422 Transceivers |
| ISL81487EIB* | 【15kV ESD Protected, 1/8 Unit Load, 5V, Low Power, High Speed or Slew Rate Limited, RS-485/RS-422 Transceivers |
| ISL81487EIBZ* | 【15kV ESD Protected, 1/8 Unit Load, 5V, Low Power, High Speed or Slew Rate Limited, RS-485/RS-422 Transceivers |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6741IBZ-T | 功能描述:IC REG CTRLR PWM CM 16-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL6741IV | 功能描述:IC REG CTRLR PWM CM 16-TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:100% 电源电压:8.2 V ~ 30 V 降压:无 升压:无 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:0°C ~ 70°C 封装/外壳:8-DIP（0.300"，7.62mm） 包装:管件 产品目录页面:1316 (CN2011-ZH PDF) |
| ISL6741IV-T | 功能描述:IC REG CTRLR PWM CM 16-TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:100% 电源电压:8.2 V ~ 30 V 降压:无 升压:无 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:0°C ~ 70°C 封装/外壳:8-DIP（0.300"，7.62mm） 包装:管件 产品目录页面:1316 (CN2011-ZH PDF) |
| ISL6741IVZ | 功能描述:IC REG CTRLR PWM CM 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL6741IVZ-T | 功能描述:IC REG CTRLR PWM CM 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
发布紧急采购，3分钟左右您将得到回复。