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| 型号： | MAX1544ETL+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 33/42页 |
| 文件大小： | 0K |
| 描述： | IC QUICK-PWM DUAL-PHASE 40-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 系列： | Quick-PWM™ |
| 应用： | 控制器，AMD Hammer |
| 输入电压： | 2 V ~ 28 V |
| 输出数： | 1 |
| 输出电压： | 0.68 V ~ 1.55 V |
| 工作温度： | -40°C ~ 100°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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Dual-Phase, Quick-PWM Controller for
AMD Hammer CPU Core Power Supplies
Output Capacitor Stability Considerations
For Quick-PWM controllers, stability is determined by
the value of the ESR zero relative to the switching fre-
quency. The boundary of instability is given by the fol-
lowing equation:
Unstable operation manifests itself in two related but
distinctly different ways: double-pulsing and feedback
loop instability. Double-pulsing occurs due to noise on
the output or because the ESR is so low that there is
not enough voltage ramp in the output voltage signal.
This “ fools ” the error comparator into triggering a new
where:
f ESR ≤
f SW
π
cycle immediately after the minimum off-time period
has expired. Double-pulsing is more annoying than
harmful, resulting in nothing worse than increased out-
put ripple. However, it can indicate the possible pres-
ence of loop instability due to insufficient ESR. Loop
and:
f ESR =
1
2 π R EFF C OUT
instability can result in oscillations at the output after
line or load steps. Such perturbations are usually
damped, but can cause the output voltage to rise
above or fall below the tolerance limits.
The easiest method for checking stability is to apply a
I RMS = ?
η OUTPH OUT IN OUTPH OUT )
? η
?
? η OUTPH V IN ?
R EFF = R ESR + A VPS R SENSE + R PCB
where C OUT is the total output capacitance, R ESR is the
total equivalent-series resistance, R SENSE is the
current-sense resistance, A VPS is the voltage-positioning
gain, and R PCB is the parasitic board resistance
between the output capacitors and sense resistors.
For a standard 300kHz application, the ESR zero fre-
quency must be well below 95kHz, preferably below
50kHz. Tantalum, Sanyo POSCAP, and Panasonic SP
capacitors in widespread use at the time of publication
have typical ESR-zero frequencies below 50kHz. For
example, the ESR needed to support a 30mV P-P ripple
in a 40A design is 30mV/(40A × 0.3) = 2.5m ? . Four
330μF/2.5V Panasonic SP (type XR) capacitors in paral-
lel provide 2.5m ? (max) ESR. Their typical combined
ESR results in a zero at 40kHz.
Ceramic capacitors have a high ESR zero frequency,
but applications with significant voltage positioning can
take advantage of their size and low ESR. Do not put
high-value ceramic capacitors directly across the
output without verifying that the circuit contains enough
voltage positioning and series PC board resistance to
ensure stability. When only using ceramic output
capacitors, output overshoot (V SOAR ) typically deter-
mines the minimum output capacitance requirement.
Their relatively low capacitance value can cause output
overshoot when stepping from full-load to no-load con-
ditions, unless a small inductor value is used (high
switching frequency) to minimize the energy transferred
from inductor to capacitor during load-step recovery.
The efficiency penalty for operating at 550kHz is about
5% when compared to the 300kHz circuit, primarily due
to the high-side MOSFET switching losses.
very fast zero-to-max load transient and carefully
observe the output voltage ripple envelope for over-
shoot and ringing. It can help to simultaneously monitor
the inductor current with an AC current probe. Do not
allow more than one cycle of ringing after the initial
step-response under/overshoot.
Input Capacitor Selection
The input capacitor must meet the ripple current
requirement (I RMS ) imposed by the switching currents.
The multiphase Quick-PWM controllers operate out-of-
phase, while the Quick-PWM slave controllers provide
selectable out-of-phase or in-phase on-time triggering.
Out-of-phase operation reduces the RMS input current
by dividing the input current between several stag-
gered stages. For duty cycles less than 100%/ η OUTPH
per phase, the I RMS requirements may be determined
by the following equation:
? I LOAD ?
V ( V V
where η OUTPH is the total number of out-of-phase switch-
ing regulators. The worst-case RMS current requirement
occurs when operating with V IN = 2 η OUTPH V OUT . At this
point, the above equation simplifies to I RMS = 0.5 ×
I LOAD / η OUTPH .
For most applications, nontantalum chemistries (ceramic,
aluminum, or OS-CON ? ) are preferred due to their resis-
tance to inrush surge currents typical of systems with a
mechanical switch or connector in series with the input. If
the Quick-PWM controller 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 cir-
cuit longevity.
OS-CON is a trademark of Sanyo.
______________________________________________________________________________________
33
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1544ETL+ | 功能描述:电压模式 PWM 控制器 Dual-Phase Quick-PWM Controller 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 |
| MAX1544ETL+T | 功能描述:电压模式 PWM 控制器 Dual-Phase Quick-PWM Controller 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 |
| MAX1544ETL+TG075 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1544ETL-T | 功能描述:电压模式 PWM 控制器 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 |
| MAX1544EVKIT | 制造商:Maxim Integrated Products 功能描述:DUAL-PHASE, QUICK-PWM CONTROLLER FOR AMD HAMM - Bulk |
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