参数资料
| 型号： | ISL62881HRTZ |
| 厂商： | Intersil |
| 文件页数： | 13/35页 |
| 文件大小： | 0K |
| 描述： | IC REG PWM SGL PHASE 28TQFN |
| 标准包装： | 75 |
| 应用： | 控制器，Intel IMVP-6.5? |
| 输入电压： | 5 V ~ 25 V |
| 输出数： | 1 |
| 输出电压： | 0.013 V ~ 1.5 V |
| 工作温度： | -10°C ~ 100°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 管件 |
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ISL62881, ISL62881B
Diode Emulation and Period Stretching
PHASE
UGATE
LGATE
IL
FIGURE 8. DIODE EMULATION
ISL62881 can operate in diode emulation (DE) mode to improve
light load efficiency. In DE mode, the low-side MOSFET conducts
when the current is flowing from source to drain and doesn’t not
allow reverse current, emulating a diode. As shown in Figure 8,
when LGATE is on, the low-side MOSFET carries current, creating
negative voltage on the phase node due to the voltage drop
across the ON-resistance. The ISL62881 monitors the current
through monitoring the phase node voltage. It turns off LGATE
when the phase node voltage reaches zero to prevent the
inductor current from reversing the direction and creating
unnecessary power loss.
If the load current is light enough, as Figure 9 shows, the inductor
current will reach and stay at zero before the next phase node
pulse, and the regulator is in discontinuous conduction mode
(DCM). If the load current is heavy enough, the inductor current
will never reach 0A, and the regulator is in CCM although the
controller is in DE mode.
window size, therefore is the same, making the inductor current
triangle the same in the three cases. The ISL62881 clamps the
ripple capacitor voltage V crs in DE mode to make it mimic the
inductor current. It takes the COMP voltage longer to hit V crs ,
naturally stretching the switching period. The inductor current
triangles move further apart from each other such that the inductor
current average value is equal to the load current. The reduced
switching frequency helps increase light load efficiency.
Start-up Timing
With the controller's V DD voltage above the POR threshold, the
start-up sequence begins when VR_ON exceeds the 3.3V logic
high threshold.
Figure 10 shows the typical start-up timing when the ISL62881 is
configured for CPU VR application. The ISL62881 uses digital
soft-start to ramp up DAC to the boot voltage of 1.1V at about
2.5mV/μs. Once the output voltage is within 10% of the boot voltage
for 13 PWM cycles (43μs for frequency = 300kHz), CLK_EN# is
pulled low and DAC slews at 5mV/μs to the voltage set by the VID
pins. PGOOD is asserted high in approximately 7ms. Similar results
occur if VR_ON is tied to V DD , with the soft-start sequence starting
120μs after V DD crosses the POR threshold.
Figure 11 shows the typical start-up timing when the ISL62881 is
configured for GPU VR application. The ISL62881 uses digital
soft-start to ramp-up DAC to the voltage set by the VID pins at
5mV/μs. Once the output voltage is within 10% of the target voltage
for 13 PWM cycles (43μs for frequency = 300kHz), CLK_EN# is
pulled low. PGOOD is asserted high in approximately 7ms. Similar
results occur if VR_ON is tied to V DD , with the soft-start sequence
starting 120μs after V DD crosses the POR threshold.
VDD
CCM/DCM BOUNDARY
VR_ON
5mV/μs
VCRS
VW
800μs
2.5mV/μs
90% VBOOT
VID
COMMAND
VOLTAGE
DAC
13 SWITCHING CYCLES
IL
CLK_EN#
VCRS
VW
LIGHT DCM
PGOOD
~7ms
FIGURE 10. SOFT-START WAVEFORMS FOR CPU VR APPLICATION
IL
VCRS
VW
DEEP DCM
VDD
VR_ON
5mV/μs
90%
120μs
VID COMMAND VOLTAGE
IL
FIGURE 9. PERIOD STRETCHING
DAC
CLK_EN#
13 SWITCHING CYCLES
Figure 9 shows the operation principle in diode emulation mode at
light load. The load gets incrementally lighter in the three cases
PGOOD
~7ms
from top to bottom. The PWM on-time is determined by the VW
13
FIGURE 11. SOFT-START WAVEFORMS FOR GPU VR APPLICATION
FN6924.3
June 16, 2011
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL62881HRTZ-T | 功能描述:直流/直流开关调节器 1 PHS PWM BUCKG FOR MICROPROCESR PWR SUP RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| ISL62882 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Multiphase PWM Regulator for IMVP-6.5 Mobile CPUs and GPUs |
| ISL62882B | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Multiphase PWM Regulator for IMVP-6.5 Mobile CPUs and GPUs |
| ISL62882BHRTZ | 功能描述:直流/直流开关调节器 2 PHS PWM BUCKG FOR MICROPROC PWR SUP RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| ISL62882BHRTZR5411 | 制造商:Intersil Corporation 功能描述: |
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