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参数资料
| 型号： | MAX17000EVKIT+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 27/32页 |
| 文件大小： | 0K |
| 描述： | KIT EVAL FOR MAX17000 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 主要目的： | 特殊用途 DC/DC，DDR 存储器电源 |
| 输出及类型： | 3，非隔离 |
| 功率 - 输出： | 19.8W |
| 输出电压： | 1.8V，0.9V，0.9V |
| 电流 - 输出： | 10A，2A，3mA |
| 输入电压： | 7 ~ 20 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 300kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MAX17000 |
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MAX17000
Complete DDR2 and DDR3 Memory
Power-Management Solution
PD (NH Switching) = V IN ( MAX ) × I LOAD SW ?
? Q G ( SW ) ?
?
C × V 2 × f
? V OUT ? ?
? ? × ( I LOAD ) × R DS ( ON )
PD (NL Resistive) = ? 1 ? ?
? ? V IN ( MAX ) ? ?
PD (NH Resistive) = ? OUT ? × ( I LOAD ) × R DS ( ON )
I LOAD = ? I VALLEY ( MAX ) +
= I VALLEY ( MAX ) + ?
?
?
?
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, tanta-
lum input capacitors are acceptable. In either configu-
ration, choose an input capacitor that exhibits less than
+10°C temperature rise at the RMS input current for
optimal circuit longevity.
MOSFET Selection
Most of the following MOSFET guidelines focus on the
challenge of obtaining high load-current capability
when using high-voltage (> 20V) AC adapters. Low-
current applications usually require less attention.
The high-side MOSFET (N H ) must be able to dissipate
the resistive losses plus the switching losses at both
V IN(MIN) and V IN(MAX) . Calculate both these sums.
Ideally, the losses at V IN(MIN) should be roughly equal to
losses at V IN(MAX) , with lower losses in between. If the
losses at V IN(MIN) are significantly higher than the losses
at V IN(MAX) , consider increasing the size of N H (reducing
R DS(ON) but with higher C GATE ). Conversely, if the loss-
es at V IN(MAX) are significantly higher than the losses at
V IN(MIN) , consider reducing the size of N H (increasing
R DS(ON) to lower C GATE ). If V IN does not vary over a
wide range, the minimum power dissipation occurs
where the resistive losses equal the switching losses.
Choose a low-side MOSFET that has the lowest possi-
ble on-resistance (R DS(ON) ), comes in a moderate-sized
package (i.e., one or two 8-pin SOs, DPAK, or D 2 PAK),
and is reasonably priced. Make sure that the DL gate
driver can supply sufficient current to support the gate
charge and the current injected into the parasitic gate-
to-drain capacitor caused by the high-side MOSFET
turning on; otherwise, cross-conduction problems can
occur (see the MOSFET Gate Drivers (DH, DL) section).
MOSFET Power Dissipation
Worst-case conduction losses occur at the duty factor
extremes. For the high-side MOSFET (N H ), the worst-
case power dissipation due to resistance occurs at the
minimum input voltage:
? V ? 2
? V IN ?
Generally, a small high-side MOSFET is desired to
reduce switching losses at high input voltages.
However, the R DS(ON) required to stay within package
power dissipation often limits how small the MOSFET
Maxim Integrated
can be. Again, the optimum occurs when the switching
losses equal the conduction (R DS(ON) ) losses. High-
side switching losses do not usually become an issue
until the input is greater than approximately 15V.
Calculating the power dissipation in high-side MOSFET
(N H ) due to switching losses is difficult since it must
allow for difficult quantifying factors that influence the
turn-on and turn-off times. These factors include the
internal gate resistance, gate charge, threshold voltage,
source inductance, and PCB layout characteristics. The
following switching-loss calculation provides only a very
rough estimate and is no substitute for breadboard
evaluation, preferably including verification using a
thermocouple mounted on N H :
× f
? I GATE ?
+ O S S IN SW
2
where C OSS is the N H MOSFET’s output capacitance,
Q G(SW) is the charge needed to turn on the N H MOS-
FET, and I GATE is the peak gate-drive source/sink cur-
rent (2.2A typ).
Switching losses in the high-side MOSFET can become
an insidious heat problem when maximum AC adapter
voltages are applied, due to the squared term in the C
x V IN 2 x f SW switching-loss equation. If the high-side
MOSFET chosen for adequate R DS(ON) at low battery
voltages becomes extraordinarily hot when biased from
V IN(MAX) , consider choosing another MOSFET with
lower parasitic capacitance.
For the low-side MOSFET (N L ), the worst-case power
dissipation always occurs at maximum input voltage:
? 2
?
The worst case for MOSFET power dissipation occurs
under heavy overloads that are greater than
I LOAD(MAX) , but are not quite high enough to exceed
the current limit and cause the fault latch to trip. To pro-
tect against this possibility, the circuit can be “over
designed” to tolerate:
? Δ I INDUCTOR ?
?
? 2 ?
? I LOAD(MAX ) × LIR ?
2
27
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17000EVKIT+ | 功能描述:电源管理IC开发工具 MAX17000 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX17003AETJ+ | 功能描述:电压模式 PWM 控制器 Quad Out Main Power Supply 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 |
| MAX17003AETJ+T | 功能描述:电压模式 PWM 控制器 Quad Out Main Power Supply 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 |
| MAX17003ETJ+ | 功能描述:电压模式 PWM 控制器 Quad Out Main Power Supply 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 |
| MAX17003ETJ+T | 功能描述:电压模式 PWM 控制器 Quad Out Main Power Supply 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 |
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