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| 型号： | MAX1937EEI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 20/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM HYBRID 28-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| PWM 型： | 混合物 |
| 输出数： | 1 |
| 频率 - 最大： | 500kHz |
| 占空比： | 50% |
| 电源电压： | 6 V ~ 24 V |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 85°C |
| 封装/外壳： | 28-QSOP |
| 包装： | 带卷 (TR) |
Two-Phase Desktop CPU Core Supply
Controllers with Controlled VID Change
V ILIM is set from 0.5V to 2V by connecting ILIM to a
resistor-divider from REF to GND. Select resistors R3
and R4 such that the current through the divider is at
least 5μA:
P D ( HS ) COND =
V OUT × I 2 LOADMAX × R DS( ON)
4 × V IN
R 3 + R 4 ≤ 400 k Ω
A typical value for R3 is 200k Ω ; then solve for R4 using:
where R DS(ON) is the on-resistance of the high-side
MOSFET and V IN is the input voltage. To minimize con-
duction losses, select a MOSFET with a low R DS(ON) .
Switching losses are also a major contributor to power
R 4 = R 3 ×
V ILIM
2 ? V ILIM
dissipation in the high-side MOSFET. Switching losses
are difficult to precisely calculate and should be mea-
sured in the circuit. To estimate the switching losses,
use the following equation:
P D ( HS ) SW ? ( I PEAK × t fall + I VALLEY × t rise ) IN SW
V OUT = V VID ? g m ( VPOS ) × R VPOS × ? OUT CS ?
P D ( LS ) COND = ? 1 ? OUT ? × × R DS ( ON )
P D ( LS ) SW ? LOADMAX × t DT DF SW
× V
× f
Setting the Voltage Positioning
Voltage positioning dynamically changes the output-
voltage set point in response to the load current. When
the output is loaded, the signals fed back from the cur-
rent-sense inputs adjust the output voltage set point,
thereby decreasing power dissipation. The load-tran-
sient response of this control loop is extremely fast yet
well controlled, so the amount of voltage change can
be accurately confined within the limits stipulated in the
microprocessor power-supply guidelines. To under-
stand the benefits of dynamically adjusting the output
voltage, see the Voltage Positioning (VPOS) section.
The amount of output voltage change is adjusted by an
external gain resistor (R VPOS ). Connect R VPOS between
REF and VPOS. The output voltage changes in response
to the load current as follows:
? I × R ?
? 2 ?
where V VID is the programmed output voltage set by
the VID code (Table 1), and the voltage-positioning
transconductance (g m(VPOS) ) is typically 20μS. R CS is
the value of the current-sense resistor connected from
CS_ to PGND. If the on-resistance of the low-side
MOSFETs is used instead of current-sense resistors for
current sensing, then use the maximum on-resistance
of the low-side MOSFETs for R CS in the equation
above.
MOSFET Power Dissipation
Power dissipation in the high-side MOSFET is worst at
high duty cycles (maximum output voltage, minimum
input voltage). Two major factors contribute to the high-
side power dissipation, conduction losses, and switch-
ing losses. Conduction losses are because of current
flowing through a resistance, and can be calculated
from:
V × f
2
where I PEAK and I VALLEY are the maximum peak and
valley inductor currents, t FALL and t RISE are the fall and
rise times of the high-side MOSFET, and f SW is the
switching frequency (about 250kHz).
The total power dissipated in the high-side MOSFET is
then found from:
P D(HS) = P D(HS)COND + P D(HS)SW
The power dissipation in the low-side MOSFET is high-
est at low duty cycles (high input voltage, low output
voltage), and is mainly because of conduction losses:
? V ? I 2 LOADMAX
? V IN ? 4
Switching losses in the low-side MOSFET are small
because of its voltage being clamped by the body
diode. Switching losses can be estimated from:
I
2
where I LOADMAX/2 is the maximum average inductor
current, t DT is the time/cycle that the low-side MOSFET
conducts through its body diode, and V DF is the for-
ward voltage drop across the body diode.
The total power dissipation in the low-side MOSFET is:
P D(LS) = P D(LS)COND + P D(LS)SW
IC Power Dissipation
During normal operation, power dissipation in the con-
troller is mostly from the gate drivers. This can be cal-
culated from the following equation:
P GATE = 2 ? V VLG ? f SW ? ( Q GH + Q GL )
20
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1937EEI-TG069 | 制造商:Maxim Integrated Products 功能描述: |
| MAX1938EEI | 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 |
| MAX1938EEI-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 |
| MAX1938EEI-TG069 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1938EVKIT | 功能描述:电源管理IC开发工具 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 |
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