参数资料
| 型号： | ISL6308IRZ |
| 厂商： | Intersil |
| 文件页数： | 20/28页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR PWM 3PHASE BUCK 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： | -40°C ~ 85°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 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页当前第20页第21页第22页第23页第24页第25页第26页第27页第28页
ISL6308
dissipation in the controller itself, P DR , can be roughly
estimated as:
rise in order to cause proportionally less current to flow in the
hotter phase.
Δ T 2
R ISEN , 2 = R ISEN ? ----------
P DR = P DR_UP + P DR_LOW + P BOOT + ( I Q ? VCC )
(EQ. 22)
Δ T 1
(EQ. 24)
P BOOT = ---------------------
P DR_UP = ? -------------------------------------- + ---------------------------------------- ? ? ---------------------
? R HI1 + R EXT1 R LO1 + R EXT1 ?
P DR_LOW = ? -------------------------------------- + ---------------------------------------- ? ? ---------------------
? R HI2 + R EXT2 R LO2 + R EXT2 ?
P Qg_Q1
3
? R HI1 R LO1 ? P Qg_Q1
? R HI2 R LO2 ? P Qg_Q2
3
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 ISL6308 senses the total
Current Balancing Component Selection
The ISL6308 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 current by detecting the voltage across the output
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
R ISEN = ----------------------- ?
I FL
r DS ( ON )
50 ? 10 – 6
--------
N
(EQ. 23)
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
V IN
CHANNEL N
UPPER MOSFET
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 = ---------------------------------------
ISEN(n)
I L
calculate the value for R COMP .
L
DCR ? C COMP
(EQ. 25)
R S = ------------------------- ? R COMP ? DCR
ISL6308
R ISEN
CHANNEL N
LOWER MOSFET
-
+
I L x r DS ( ON )
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
voltage, V DROOP , and inductor DCR in Equation 26 to
calculate the value for R S .
I FL (EQ. 26)
V DROOP
FIGURE 17. ISL6308 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 affected
phases (see “Channel Current Balance” on page 10). Choose
R ISEN,2 in proportion to the desired decrease in temperature
20
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.
FN9208.4
September 30, 2008
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| ISL6308IRZ-T | 功能描述:电压模式 PWM 控制器 DAC-LESS MULTI-PHS PWM CNTRLR W/3-DRVRS RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| ISL6308IRZ-TR5453 | 制造商:Intersil Corporation 功能描述:STD. ISL6308IRZ-T WITH GOLD BOND WIRE ONLY - Tape and Reel |
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| ISL6310CRZ-T | 功能描述:电压模式 PWM 控制器 W/ANNEAL 2-PH PWM CNTRLR W/2-DRVRS RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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