参数资料
| 型号： | ISL6308ACRZ |
| 厂商： | Intersil |
| 文件页数： | 20/28页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR PWM BUCK 3PHASE 40-QFN |
| 标准包装： | 500 |
| 应用： | 控制器，DDR |
| 输入电压： | 5 V ~ 12 V |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 2.3 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-VFQFN 裸露焊盘 |
| 供应商设备封装： | 40-QFN（6x6） |
| 包装： | 管件 |
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ISL6308A
The total gate drive power losses are dissipated among the
resistive components along the transition path and in the
bootstrap diode. The portion of the total power dissipated in
the controller itself is the power dissipated in the upper drive
path resistance, P DR_UP , the lower drive path resistance,
P DR_UP , and in the boot strap diode, P BOOT . The rest of the
power will be dissipated by the external gate resistors (R G1
and R G2 ) and the internal gate resistors (R GI1 and R GI2 ) of
the MOSFETs. Figures 15 and 16 show the typical upper
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
page 11). 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.
R ISEN , 2 = R ISEN ? ----------
and lower gate drives turn-on transition path. The total power
dissipation in the controller itself, P DR , can be roughly
estimated as:
Δ T 2
Δ T 1
(EQ. 24)
P BOOT = --------------------- (EQ. 22)
P DR_UP = ? -------------------------------------- + ---------------------------------------- ? ? ---------------------
? R HI1 + R EXT1 R LO1 + R EXT1 ?
P DR_LOW = ? -------------------------------------- + ---------------------------------------- ? ? ---------------------
? R HI2 + R EXT2 R LO2 + R EXT2 ?
P DR = P DR_UP + P DR_LOW + P BOOT + ( I Q ? VCC )
P Qg_Q1
3
? R HI1 R LO1 ? P Qg_Q1
3
? R HI2 R LO2 ? P Qg_Q2
2
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
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
R EXT1 = R G1 + -------------
R EXT2 = R G2 + -------------
R GI1
N Q1
R GI2
N Q2
Current Sensing)
For accurate load line regulation, the ISL6308A senses the
total output current by detecting the voltage across the output
R ISEN = ----------------------- ? --------
50 ? 10
Current Balancing Component Selection
The ISL6308A 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.
r DS ( ON ) I FL (EQ. 23)
– 6 N
V IN
CHANNEL N
UPPER MOSFET
inductor DCR of each channel (as described in “Load-Line
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
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
R COMP = ---------------------------------------
I L
calculate the value for R COMP .
L
DCR ? C COMP
(EQ. 25)
ISEN(n)
R ISEN
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
ISL6308A
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
Due to errors in the inductance or DCR it may be necessary
FIGURE 17. ISL6308A INTERNAL AND EXTERNAL CURRENT-
SENSING CIRCUITRY
20
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
FN6669.0
September 9, 2008
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| ISL6308ACRZR5609 | 制造商:Intersil Corporation 功能描述:PB-FREE DAC-LESS MULTI-PHASE PWM CONTR W/3-DRIVERS, HARD WI - Rail/Tube |
| ISL6308ACRZ-T | 功能描述:IC CTRLR PWM BUCK 3PHASE 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
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| ISL6308AIRZ | 功能描述:IC CTRLR PWM BUCK 3PHASE 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
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