参数资料
| 型号： | ISL6740AIVZA |
| 厂商： | Intersil |
| 文件页数： | 11/14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
V IN
R1
The voltage amplitude of C T ranges from 1.6V to 4.2V as the
voltage on UV increases. The UV threshold defines the
minimum amplitude of C T and corresponds to maximum duty
cycle operation.
For unregulated bus converters and DC transformers, feed
R2
R3
1.00V
10 μ A
+
-
forward can compensate for input voltage variations without a
closed loop feedback network. A resistive voltage divider from
V REF to V ERROR sets the feed forward control voltage. For
example, if the desired duty cycle at the minimum operating
ON
voltage is 90%, then:
V ERROR = D max ( V UV ? FF ? 0.8 ) + 0.8
= 0.9 ( 1.0 ? 0.8 ) + 0.8 = 1.52
V
V
(EQ. 11)
V IN ( DOWN ) = ----------------------
V
(EQ. 7)
? ? R1 + R3 ? ? ---------------------- ? ?
Δ V = 10
V
(EQ. 8)
FIGURE 5. UV HYSTERESIS
As V IN decreases to a UV condition, the threshold level is:
R1 + R2
R2
The hysteresis voltage, Δ V, is:
– 5 R1 + R2
? R2 ?
Setting R3 equal to zero results in the minimum hysteresis,
and yields:
Overcurrent Protection
There are two overcurrent protection mechanisms in the
ISL6740A, one for light overcurrent and one for heavy over
load. They are referred to, respectively, as overcurrent
protection and short circuit protection.
OVERCURRENT OPERATION
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
Δ V = 10
– 5
? R1
V
(EQ. 9)
capacitor is allowed to discharge through a 15μA source. At
the same time a 50μs re-triggerable one-shot timer is
V IN ( UP ) = V IN ( DOWN ) + Δ V
As V IN increases from a UV condition, the threshold level is:
V (EQ. 10)
Output voltage variation caused by changes in the supply
voltage may be virtually removed through a technique known
as feed forward compensation. Using feed forward, the duty
cycle is directly modulated based on changes in the input
voltage only. No closed loop feedback system is required. The
feed forward circuit uses the voltage applied to the UV/FF pin
to modulate the oscillator ramp amplitude with minimal effect
on the switching frequency and deadtime of the oscillator. The
activated. It remains active for 50μs 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 50μs prior
to the soft-start voltage decreasing to 4.25V, the soft-start
charging currents revert to normal operation and the soft-start
voltage is allowed to recover.
4.5 V
SS
voltage feed forward operates over a 3:1 input voltage range.
0.6 V OC
V UV/FF
CS
OUTA
V ERROR
CT
OUTA
OUTB
FIGURE 7. PULSE-BY-PULSE OC BEHAVIOR DURING SS
OUTB
Figure 7 shows the overcurrent behavior during SS. Although
an overcurrent condition exists, a shutdown is not allowed prior
FIGURE 6. FEED FORWARD BEHAVIOR
The voltage applied to the UV/FF pin is multiplied by 0.8 and
output on the R TC and R TD pins. This voltage is also summed
with the C T valley threshold voltage (0.8 V) to create the C T
peak threshold voltage. As the voltage applied to UV/FF varies,
the CT peak voltage and the CT charge and discharge currents
vary, all in direct proportion to each other. The result is an
amplitude modulated sawtooth waveform on C T that is
frequency invariant.
11
to completion of the SS cycle. Only peak current limit operates
during the soft-start cycle. If the overcurrent condition were to
continue beyond the soft-start cycle, a delayed overcurrent
shutdown would occur as shown in Figure 8.
FN9195.3
February 9, 2012
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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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