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| 型号： | ISL8103CRZ |
| 厂商： | Intersil |
| 文件页数： | 20/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 40-QFN |
| 标准包装： | 50 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1.5MHz |
| 占空比： | 66.6% |
| 电源电压： | 4.75 V ~ 12.6 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： | 0°C ~ 70°C |
| 封装/外壳： | 40-VFQFN 裸露焊盘 |
| 包装： | 管件 |
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ISL8103
Current Balancing Component Selection
The ISL8103 senses the channel load current by sampling
the voltage across the lower MOSFET r DS(ON) , as shown in
Figure 17. The ISEN pins are denoted ISEN1, ISEN2, and
ISEN3. The resistors connected between these pins and the
respective phase nodes determine the gains in the channel
current balance loop.
Select values for these resistors based on the room
temperature r DS(ON) of the lower MOSFETs; the full load
operating current, I FL ; and the number of phases, N using
Equation 23.
output inductor DCR of each channel (As described in
illustrates, an R-C network is required to accurately sense
the inductor DCR voltage and convert this information into a
droop voltage, which is proportional to the total output
current.
Choosing the components for this current sense network is a
two step process. First, R COMP and C COMP must be
chosen so that the time constant of this R COMP -C COMP
network matches the time constant of the inductor L/DCR.
Then the resistor R S must be chosen to set the current
R ISEN = ----------------------- ?
I FL
R COMP = ---------------------------------------
r DS ( ON )
50 ? 10 – 6
--------
N
ISEN(n)
R ISEN
V IN
(EQ. 23)
CHANNEL N
UPPER MOSFET
I L
-
sense network gain, obtaining the desired full load droop
voltage. Follow the steps below to choose the component
values for this R-C network.
1. Choose an arbitrary value for C COMP . The recommended
value is 0.01μF.
2. Plug the inductor L and DCR component values, and the
values for C COMP chosen in steps 1, into Equation 25 to
calculate the value for R COMP .
L
(EQ. 25)
DCR ? C COMP
3. Use the new value for R COMP obtained from Equation 25,
as well as the desired full load current, I FL , full load droop
R S = ------------------------- ? R COMP ? DCR
ISL8103
CHANNEL N
LOWER MOSFET
+
I L x r DS ( ON )
voltage, V DROOP , and inductor DCR in Equation 26 to
calculate the value for R S .
I FL
(EQ. 26)
V DROOP
FIGURE 17. ISL8103 INTERNAL AND EXTERNAL CURRENT-
SENSING CIRCUITRY
In certain circumstances, it may be necessary to adjust the
value of one or more ISEN resistors. When the components
of one or more channels are inhibited from effectively
dissipating their heat so that the affected channels run hotter
than desired, choose new, smaller values of R ISEN for the
Balance). Choose R ISEN,2 in proportion to the desired
decrease in temperature rise in order to cause proportionally
less current to flow in the hotter phase.
Due to errors in the inductance or DCR it may be necessary
to adjust the value of R COMP to match the time constants
correctly. The effects of time constant mismatch can be seen
in the form of droop overshoot or undershoot during the
initial load transient spike, as shown in Figure 18. Follow the
steps below to ensure the R-C and inductor L/DCR time
constants are matched accurately.
1. Capture a transient event with the oscilloscope set to
about L/DCR/2 (sec/div). For example, with L = 1μH and
DCR = 1m Ω , set the oscilloscope to 500μs/div.
R ISEN , 2 = R ISEN ? ----------
Δ T 2
Δ T 1
(EQ. 24)
2. Record Δ V1 and Δ V2 as shown in Figure 18.
3. Select a new value, R COMP,2 , for the time constant
resistor based on the original value, R COMP,1 , using the
R COMP , 2 = R COMP , 1 ? ----------
Δ V
In Equation 24, make sure that Δ T 2 is the desired
temperature rise above the ambient temperature, and Δ T 1 is
the measured temperature rise above the ambient
temperature. While a single adjustment according to
following equation.
Δ V 1
2
(EQ. 27)
Equation 24 is usually sufficient, it may occasionally be
necessary to adjust R ISEN two or more times to achieve
optimal thermal balance between all channels.
Load Line Regulation Component Selection (DCR
Current Sensing)
For accurate load line regulation, the ISL8103 senses the
total output current by detecting the voltage across the
20
4. Replace R COMP with the new value and check to see that
the error is corrected. Repeat the procedure if necessary.
After choosing a new value for R COMP , it will most likely be
necessary to adjust the value of R S to obtain the desired full
load droop voltage. Use Equation 26 to obtain the new value
for R S.
FN9246.1
July 21, 2008
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相关代理商/技术参数 |
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| ISL8103CRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 40-QFN RoHS:是 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) |
| ISL8103EVAL1 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Three-Phase Buck PWM Controller with High Current Integrated MOSFET Drivers |
| ISL8103IRZ | 功能描述:IC REG CTRLR BUCK PWM VM 40-QFN RoHS:是 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) |
| ISL8103IRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:75 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.3 V ~ 13.5 V 降压:是 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:0°C ~ 70°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:管件 产品目录页面:1051 (CN2011-ZH PDF) 其它名称:296-2543-5 |
| ISL8104 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Synchronous Buck Pulse-Width Modulator (PWM) Controller |
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