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| 型号： | MAX8707ETL+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 32/37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 |
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Multiphase, Fixed-Frequency Controller for
AMD Hammer CPU Core Power Supplies
The capacitance value required is determined primarily
by the output transient-response requirements. Low
inductor values allow the inductor current to slew faster,
replenishing the charge removed from or added to the
output filter capacitors by a sudden load step.
Therefore, the amount of output soar when the load is
removed is a function of the output voltage and induc-
tor value. The minimum output capacitance required to
prevent overshoot (V SOAR ) due to stored inductor ener-
gy can be calculated as:
Setting Voltage Positioning
Voltage positioning dynamically lowers the output volt-
age in response to the load current, reducing the out-
put capacitance and processor ’ s power-dissipation
requirements. The controller uses two transconduc-
tance amplifiers to set the transient and DC output volt-
age droop ( Figure 2). The transient-compensation
(TRC) amplifier determines how quickly the MAX8707
responds to the load transient. The slower voltage-posi-
tioning (VPS) amplifier adjusts the steady-state regula-
C OUT ≥
( ? I LOAD ( MAX ) ) 2 L
2 η PH V OUT V SOAR
tion voltage as a function of the load. This adjustability
allows flexibility in the selected current-sense resistor
value or inductor DCR, and allows smaller current-
sense resistance to be used, reducing the overall
where η PH is the total number of active phases. When
using low-capacity ceramic filter capacitors, capacitor
size is usually determined by the capacity needed to
prevent V SOAR from causing problems during load
transients. Generally, once enough capacitance is
added to meet the overshoot requirement, undershoot
power dissipated.
Steady-State Voltage Positioning
Connect a resistor (R VPS ) between VPS and FBS to set
the DC steady-state droop (load line) based on the
required DC voltage-positioning slope (R DROOP ):
at the rising load edge is no longer a problem.
Input Capacitor Selection
The input capacitor must meet the ripple-current
R VPS =
R DROOP
R SENSE G M ( VPS )
I RMS = ? LOAD ? η PH OUT IN PH OUT )
( V ? η
? η PH V IN ?
requirement (I RMS ) imposed by the switching currents.
The multiphase controllers operate out-of-phase, which
reduces the RMS input current by dividing the input cur-
rent between several staggered stages. For duty cycles
less than 100%/ η PH per phase, the I RMS requirements
can be determined by the following equation:
? I ?
V V
where η PH is the total number of out-of-phase switching
regulators. The worst-case RMS current requirement
occurs when operating with V IN = 2 η PH V OUT . At this
point, the above equation simplifies to I RMS = 0.5 x
I LOAD / η PH .
For most applications, nontantalum chemistries (ceram-
ic, aluminum, or OS-CON) are preferred due to their
resistance to inrush surge currents, typical of systems
with a mechanical switch or connector in series with the
input. If the MAX8707 is operated as the second stage
of a two-stage power-conversion system, tantalum
input capacitors are acceptable. In either configuration,
choose an input capacitor that exhibits less than 10 ° C
temperature rise at the RMS input current for optimal
circuit longevity.
where the current-sense resistance (R SENSE ) depends
on the current-sense method, and the voltage-position-
ing amplifier ’ s transconductance (G M(VPS) ) is typically
200μS as defined in the Electrical Characteristics table .
When the MAX8707 CRS sensing is enabled, R SENSE is
defined as the accurate CRS current-sense resistance:
R SENSE = R CRS
when CRS sensing is enabled.
When the MAX8707 CRS sensing is disabled, the con-
troller sums together the input signals of the current-
sense inputs (CSP_, CSN_). These inputs typically use
the inductors ’ DC resistance (R DCR ) to sense the cur-
rent, so R SENSE is defined as the average of the effec-
tive CS current-sense resistances (see the Current
Sense section):
R SENSE = R DCR
when CRS sensing is disabled.
When the inductors ’ DCR (R DCR ) is used as the cur-
rent-sense elements (for lossless sensing), R VPS should
include an NTC thermistor to minimize the temperature
dependence of the voltage-positioning slope.
To avoid output-voltage errors caused by the voltage-
positioning current, a second transconductance ampli-
fier generates an equivalent current on the FBS input.
Accurate MAX8707 CRS sensing is disabled by con-
necting CRSP to V CC .
32
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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 |
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