Application Note 1044
OVER CURRENT AND SHORT CIRCUIT
When the converter is momentarily shorted or overloaded,
as shown in Figure 13, the converter enters hiccup mode
with a narrow duty cycle and long switching period. PGOOD
stays low during the overcurrent period; it indicates the
output voltage is within regulation limits after the short is
removed and the output completes a soft-start interval.
As shown in Figure 14, the converter can sustain a
permanent short circuit remaining in hiccup mode with a
frequency of 185Hz. The average load current and the
average power dissipation in each power component are
reduced significantly; thus, the converter can stay at a short
OVERVOLTAGE SHUTDOWN
With the COMP pin momentarily tied to a 4V voltage source
with respect to the ground, the error voltage jumps high and
the duty cycle increases. Thus, the output voltage rises up
immediately until it reaches the overvoltage threshold setting
the OV latch and triggers the PWM outputs low. PGOOD is
pulled low indicating output out of regulation, as shown in
Figure 15.
V O
without causing any permanent damage or thermal issues.
COMP
V O
I OUT
PGOOD
I O
FIGURE 15. OVERVOLTAGE WAVEFORMS
PGOOD
FIGURE 13. OVER-LOADED OUTPUT WAVEFORMS
V O
Conclusion
The superior performance of Intersil’s ISL6558 four-phase
controller, coupled with Intersil’s ISL6609 driver, has been
demonstrated in the low-profile reference design of a 40W,
500kHz interleaved DC/DC buck converter. An ultra high
efficiency of 90% at 1.35V output and 30A full load has been
achieved.
The extensive experimental results give users a better
understanding of the operation of the converter, the ISL6558
four-phase PWM controller, and the ISL6609 synchronous-
rectified driver.
I O
PGOOD
FIGURE 14. SHORT-CIRCUIT WAVEFORMS
7
AN1044.2
April 4, 2006
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ISL6559EVAL2 EVALUATION BOARD 2 ISL6559
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相关代理商/技术参数
ISL6558IB 功能描述:IC REG CTRLR BUCK PWM 16-SOIC 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR)
ISL6558IB-T 功能描述:IC REG CTRLR BUCK PWM 16-SOIC 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR)
ISL6558IBZ 功能描述:IC REG CTRLR BUCK PWM 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)
ISL6558IBZ-T 功能描述:IC REG CTRLR BUCK PWM 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)
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ISL6558IR-T 功能描述:IC REG CTRLR BUCK PWM 20-QFN 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR)
ISL6558IRZ 功能描述:IC REG CTRLR BUCK PWM 20-QFN 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)
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