参数资料
| 型号： | ISL6740AIVZA |
| 厂商： | Intersil |
| 文件页数： | 12/14页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM VM 16-TSSOP |
| 标准包装： | 960 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 2MHz |
| 占空比： | 100% |
| 电源电压： | 9 V ~ 16 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： | 无 |
| 工作温度： | -40°C ~ 105°C |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm 宽） |
| 包装： | 管件 |
ISL6740A
SS
4.5 V
1
16
4.25 V
0.27 V
2
3
VREF 15
14
0.6 V OC
CS
OUTA
4
5
6
7
ISL6740A
13
12
11
10
R
OUTB
FIGURE 8. OC SHUTDOWN BEHAVIOR
Figure 8 portrays the typical delayed overcurrent shutdown
8
SS 9
C SS
behavior. Once SS has discharged to 4.25V, the outputs are
disabled and remain that way until SS has discharged to
0.27V, and then a new SS cycle begins.
FIGURE 10. MODIFYING OC SHUTDOWN TIMING
Short Circuit Operation
SS
0.6 V OC
CS
4.25 V
OC
4.5 V
50 μ S
If the output current increases beyond the overcurrent
threshold, peak current limit will reduce the duty cycle. As the
load current continues to increase, the duty cycle continues to
decrease. A short circuit event is defined as the simultaneous
occurrence of current limit and a reduced duty cycle.
The degree of reduced duty cycle that defines a short circuit
condition is user adjustable using the SCSET input. A resistor
OUTA
OUTB
divider between R TD , R TC , or V REF and GND to RCSET sets a
threshold that is compared to the voltage on the timing capacitor,
C T . The resistor divider voltage divided by 2 corresponds to the
duty cycle below which a short circuit can exist.
D SC = ------------------- ? D max
FIGURE 9. OC RECOVERY PRIOR TO SHUTDOWN
V SCSET
2
(EQ. 12)
If the overcurrent condition is removed prior to a shutdown, a
recovery can occur as indicated in Figure 9. When the load
decreases below the overcurrent threshold and an additional
50 μ s elapses without the SS dropping below 4.25V, the
overcurrent circuitry resets and the soft-start voltage recovers.
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 nearly
double the OFF time. 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.
12
where D SC is the maximum short circuit duty cycle, V SCSET is
the voltage applied to SCSET, and D max is the maximum duty
cycle. If the timing capacitor voltage fails to exceed the
threshold before an overcurrent pulse is detected, a short
circuit condition exists. A shutdown will occur if 8 short circuit
events occur within 32 oscillator cycles. Once shutdown
occurs, SS will discharge through a 15μA current source. A
new soft-start cycle will begin when SS reaches 0.27V.
Latching shutdown may be implemented in the same manner
as described in the overcurrent section. Short circuit shutdown
is enabled once the soft-start cycle is complete. Connecting
SCSET to GND inhibits short circuit shutdown.
If either R TC ar R TD are used as the voltage source for the
divider, the effect of the SCSET divider must be included in the
timing calculations since the current sourced from R TC and
R TD determine the charge and discharge currents for the
timing capacitor. Typically the resistor between either R TC or
R TD 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%.
FN9195.3
February 9, 2012
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相关代理商/技术参数 |
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| ISL6740AIVZA-T | 功能描述:IC REG CTRLR PWM VM 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) |
| ISL6740EVAL1 | 功能描述:EVALUATION BOARD 1 ISL6740 RoHS:否 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL6740EVAL2 | 功能描述:EVALUATION BOARD 2 ISL6740 RoHS:否 类别:编程器，开发系统 >> 过时/停产零件编号 系列:- 标准包装:1 系列:- 传感器类型:CMOS 成像，彩色（RGB） 传感范围:WVGA 接口:I²C 灵敏度:60 fps 电源电压:5.7 V ~ 6.3 V 嵌入式:否 已供物品:成像器板 已用 IC / 零件:KAC-00401 相关产品:4H2099-ND - SENSOR IMAGE WVGA COLOR 48-PQFP4H2094-ND - SENSOR IMAGE WVGA MONO 48-PQFP |
| ISL6740EVAL2Z | 功能描述:EVALUATION BOARD 2 ISL6740 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL6740EVAL3Z | 制造商:Intersil Corporation 功能描述:ISL6740 EVALUATION BOARD 3 - ROHS COMPLIANT - SOIC - DSL - Bulk 制造商:Intersil Corporation 功能描述:Power Management IC Development Tools ISL6740 EVAL RD 3 ROHS CMPL DSL |
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