- 您现在的位置：买卖IC网 > PDF目录1848 > MAX8707ETL+ (Maxim Integrated Products)IC CNTRLR MULTIPHASE 40TQFN PDF资料下载
参数资料
| 型号： | MAX8707ETL+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 31/37页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR MULTIPHASE 40TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 应用： | 控制器，AMD Hammer |
| 输入电压： | 4.5 V ~ 5.5 V |
| 输出数： | 4 |
| 输出电压： | 0.8 V ~ 1.55 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-WFQFN 裸露焊盘 |
| 供应商设备封装： | 40-TQFN-EP（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页第29页第30页当前第31页第32页第33页第34页第35页第36页第37页
Multiphase, Fixed-Frequency Controller for
AMD Hammer CPU Core Power Supplies
Current Limit
Peak Inductor Current Limit (ILIM(PK))
1/20th the voltage difference between ILIM(AVE) and
the reference:
The MAX8707 overcurrent protection employs a peak
current-sensing algorithm that uses either current-
sense resistors or the inductor ’ s DCR as the current-
sense element (see the Current Sense section). Since
V LAVE =
V REF ? V ILIM( AVE)
20
the controller limits the peak inductor current, the maxi-
mum average load current is less than the peak cur-
rent-limit threshold by an amount equal to half the
inductor ripple current. Therefore, the maximum load
capability is a function of the current-sense resistance,
inductor value, switching frequency, and input voltage.
When combined with the undervoltage-protection cir-
cuit, this current-limit method is highly effective.
The peak current-limit threshold is set with a single exter-
nal resistor between ILIM(PK) and analog ground, where
the resistor is determined by the following equation:
The logic threshold for switchover to the 25mV default
value is approximately V CC - 1V. The average current-
limit circuit also prevents against excessive reverse
inductor current when V OUT is sinking current. The neg-
ative current-limit threshold is equivalent to the positive
current limit, and tracks the positive current limit when
V LAVE is adjusted.
Output-Capacitor Selection
The output filter capacitor must have low enough effec-
tive series resistance (ESR) to meet output ripple and
load-transient requirements. In CPU V CORE converters
R ILIM ( PK ) =
8 V × R TRC
I PKLIMIT R SENSE
and other applications where the output is subject to
large load transients, the output capacitor ’ s size typi-
cally depends on how much ESR is needed to prevent
the output from dipping too low under a load transient.
where R SENSE is the resistance value of the current-
sense element (inductors ’ DCR or current-sense resis-
Ignoring the sag due to finite capacitance:
tor), R TRC is the resistance between TRC and REF, and
I PKLIMIT is the desired peak current limit (per phase).
The peak current-limit-threshold voltage adjustment
( R ESR + R PCB ) ≤
V STEP
? I LOAD ( MAX )
range is from 20mV to 80mV.
The peak current-limit circuit also prevents excessive
reverse inductor currents when V OUT is sinking current.
The negative current-limit threshold is equivalent to the
positive current limit, and tracks the positive current limit
when R ILIM(PK) or R TRC are adjusted. When a phase
drops below the negative current limit, the controller acti-
vates an on-time pulse at the next clock edge, regard-
less of the error-amplifier state, until the inductor current
rises above the negative current-limit threshold.
Average Inductor Current-Limit
(ILIM(AVE))
In non-CPU applications, the output capacitor ’ s size
often depends on how much ESR is needed to maintain
an acceptable level of output ripple voltage. The output
ripple voltage of a step-down controller equals the total
inductor ripple current multiplied by the output capaci-
tor ’ s ESR. When operating multiphase systems out-of-
phase, the peak inductor currents of each phase are
staggered, resulting in lower output ripple voltage
(V RIPPLE ) by reducing the total inductor ripple current.
For nonoverlapping, multiphase operation (V IN ≥ η PH
x V OUT ), the maximum ESR to meet the output-ripple-
voltage requirement is:
? η
( V IN PH OUT OUT ? ?
The MAX8707 also uses the accurate CRSP to CRSN cur-
rent-sense voltage to limit the average current per phase.
When the average current-limit threshold is exceeded,
?
R ESR ≤ ?
? ?
V ) V
V IN f SW L ?
? V RIPPLE
the controller internally reduces the peak inductor cur-
rent-limit threshold (ILIM(PK)) until the average current
remains within the programmed limits. When the accurate
current sensing is disabled (CRSP = V CC ), the average
current-limit circuit is disabled.
The average current-limit threshold defaults to 25mV if
ILIM(AVE) is connected to V CC . In adjustable mode, the
average current-limit threshold voltage is precisely
where η PH is the total number of active phases, and f SW
is the switching frequency per phase. The actual capac-
itance value required relates to the physical size need-
ed to achieve low ESR, as well as to the chemistry of the
capacitor technology. Thus, the capacitor selection is
usually limited by ESR and voltage rating rather than by
capacitance value (this is true of polymer types).
______________________________________________________________________________________
31
相关PDF资料 |
PDF描述 |
|---|---|
| MAX8709BETI+T | IC CNTRLR CCFL HI EFF 28-TQFN |
| MAX8719ETA+T | IC REG LINEAR LP HV 8-TDFN |
| MAX871EUK+TG002 | IC VOLTAGE INV SWCAP SOT23-5 |
| MAX8720ETX+ | IC CNTRL VID STP DWN 36-TQFN |
| MAX8722CEEG+ | IC CCFL BACKLIGHT CTRL 24-QSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8707ETL+ | 功能描述:DC/DC 开关控制器 Multiphase Fixed Frequency Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX8707ETL+T | 功能描述:DC/DC 开关控制器 Multiphase Fixed Frequency Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX8707ETL-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX8708ETJ | 制造商:Maxim Integrated Products 功能描述:AMD CPU CORE SUPPLY - Rail/Tube |
| MAX8708ETJ-T | 制造商:Maxim Integrated Products 功能描述:AMD CPU CORE SUPPLY - Tape and Reel |
发布紧急采购，3分钟左右您将得到回复。