- 您现在的位置：买卖IC网 > PDF目录15138 > MAX1634AEAI+T (Maxim Integrated Products)IC REG CTRLR BUCK PWM CM 28-SSOP PDF资料下载
参数资料
| 型号： | MAX1634AEAI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 20/29页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,000 |
| PWM 型： | 电流模式，混合 |
| 输出数： | 2 |
| 频率 - 最大： | 330kHz |
| 占空比： | 99% |
| 电源电压： | 4.2 V ~ 30 V |
| 降压： | 是 |
| 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： | -40°C ~ 85°C |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
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页当前第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
Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
full equation for ripple in continuous-conduction mode
is V NOISE (P-P) = I RIPPLE x [R ESR + 1/(2 x π x f x
C OUT )]. In Idle Mode, the inductor current becomes
discontinuous, with high peaks and widely spaced
pulses, so the noise can actually be higher at light load
(compared to full load). In Idle Mode, calculate the out-
put ripple as follows:
VOUT(MIN) = the minimum value of the main output
voltage (from the Electrical Characteristics)
V RECT = the on-state voltage drop across the synchro-
nous rectifier MOSFET
V SENSE = the voltage drop across the sense resistor
In positive-output applications, the transformer sec-
ondary return is often referred to the main output volt-
+
V NOISE(P-P) =
0.02 x R ESR
R SENSE
0.0003 x Lx [ 1 / V OUT + 1 / (V IN - V OUT ) ]
(R SENSE ) 2 x C OUT
age, rather than to ground, to reduce the needed turns
ratio. In this case, the main output voltage must first be
subtracted from the secondary voltage to obtain V SEC .
Selecting Other Components
MOSFET Switches
Transformer Design
(for Auxiliary Outputs Only)
Buck-plus-flyback applications, sometimes called “cou-
pled-inductor” topologies, need a transformer to gener-
ate multiple output voltages. Performing the basic
electrical design is a simple task of calculating turns
ratios and adding the power delivered to the secondary
to calculate the current-sense resistor and primary
inductance. However, extremes of low input-output dif-
ferentials, widely different output loading levels, and
high turns ratios can complicate the design due to par-
asitic transformer parameters such as interwinding
capacitance, secondary resistance, and leakage
inductance. For examples of what is possible with real-
world transformers, see the Maximum Secondary
Current vs. Input Voltage graph in the Typical
Operating Characteristics section.
Power from the main and secondary outputs is combined
to get an equivalent current referred to the main output
voltage (see the Inductor Value section for parameter def-
initions). Set the current-sense resistor resistor value at
80mV / I TOTAL .
P TOTAL = The sum of the output power from all outputs
I TOTAL = P TOTAL / V OUT = The equivalent output cur-
rent referred to V OUT :
The high-current n-channel MOSFETs must be logic-level
types with guaranteed on-resistance specifications at
V GS = 4.5V. Lower gate threshold specifications are bet-
ter (i.e., 2V max rather than 3V max). Drain-source break-
down voltage ratings must at least equal the maximum
input voltage, preferably with a 20% derating factor. The
best MOSFETs have the lowest on-resistance per
nanocoulomb of gate charge. Multiplying R DS(ON) x Q G
provides a good figure for comparing various MOSFETs.
Newer MOSFET process technologies with dense cell
structures generally perform best. The internal gate dri-
vers tolerate >100nC total gate charge, but 70nC is a
more practical upper limit to maintain best switching
times.
In high-current applications, MOSFET package power
dissipation often becomes a dominant design factor. I 2 R
power losses are the greatest heat contributor for both
high-side and low-side MOSFETs. I 2 R losses are distrib-
uted between Q1 and Q2 according to duty factor (see
the following equations). Generally, switching losses
affect only the upper MOSFET, since the Schottky rectifier
clamps the switching node in most cases before the syn-
chronous rectifier turns on. Gate-charge losses are dissi-
pated by the driver and do not heat the MOSFET.
Calculate the temperature rise according to package
thermal-resistance specifications to ensure that both
MOSFETs are within their maximum junction temperature
PD(upper FET) = (I LOAD ) x R DS(ON) x DUTY
L(primary) =
Turns Ratio N =
V OUT (V IN(MAX) - V OUT )
V IN(MAX) xfxI TOTAL x LIR
V SEC + V FWD
V OUT(MIN) + V RECT + V SENSE
at high ambient temperature. The worst-case dissipation
for the high-side MOSFET occurs at both extremes of
input voltage, and the worst-case dissipation for the low-
side MOSFET occurs at maximum input voltage:
2
+ V IN LOAD x f x ? IN RSS + 20ns ?
PD(lower FET) = (I LOAD ) x R DS(ON) x (1 - DUTY)
where:
V SEC = the minimum required rectified secondary out-
put voltage
V FWD = the forward drop across the secondary
rectifier
? V xC ?
xI
? I GATE ?
2
DUTY = (V OUT + V Q2 ) / (V IN - V Q1 )
20
______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| SLP681M160C5P3 | CAP ALUM 680UF 160V 20% SNAP |
| EMC15DRAS | CONN EDGECARD 30POS R/A .100 SLD |
| MAX1717BEEG+T | IC REG CTRLR BUCK PWM CM 24-QSOP |
| UCD2A151MNQ1MS | CAP ALUM 150UF 100V 20% SMD |
| GBB15DHAS | CONN EDGECARD 30POS R/A .050 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1634CAI | 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 |
| MAX1634CAI+ | 功能描述:DC/DC 开关控制器 Multi-Out Low-Noise Power-Supply Ctlr 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 |
| MAX1634CAI+T | 功能描述:DC/DC 开关控制器 Multi-Out Low-Noise Power-Supply Ctlr 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 |
| MAX1634CAI-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 |
| MAX1634EAI | 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 |
发布紧急采购，3分钟左右您将得到回复。