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| 型号： | MAX1634AEAI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 18/29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) |
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Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
rate output of more than 120mA is needed, an external
pass transistor can be added. Figure 6’s circuit delivers
more than 200mA. Total output current is constrained
by the V+ input voltage and the transformer primary
load (see Maximum 15V V DD Output Current vs.
Supply Voltage graphs in the Typical Operating
Characteristics ).
__________________Design Procedure
The three predesigned 3V/5V standard application cir-
cuits (Figure 1 and Table 1) contain ready-to-use solu-
tions for common application needs. Also, two standard
flyback transformer circuits support the 12OUT linear
regulator in the Applications Information section. Use
the following design procedure to optimize these basic
schematics for different voltage or current require-
ments. Before beginning a design, firmly establish the
following:
? Maximum input (battery) voltage, V IN(MAX) . This
value should include the worst-case conditions,
such as no-load operation when a battery charger
or AC adapter is connected but no battery is
installed. V IN(MAX) must not exceed 30V.
intended mainly for high-efficiency, battery-powered
applications. Refer to Appendix A in Maxim’s Battery
Management and DC-DC Converter Circuit Collection
for crossover-point and discontinuous-mode equations.
Discontinuous conduction doesn’t affect normal Idle
Mode operation.
Three key inductor parameters must be specified:
inductance value (L), peak current (I PEAK ), and DC
resistance (R DC ). The following equation includes a
constant, LIR, which is the ratio of inductor peak-to-
peak AC current to DC load current. A higher LIR value
allows smaller inductance, but results in higher losses
and higher ripple. A good compromise between size
and losses is found at a 30% ripple-current to load-
current ratio (LIR = 0.3), which corresponds to a peak
inductor current 1.15 times higher than the DC load
current:
V OUT ( V IN(MAX) - V OUT )
L =
V IN(MAX) x f x I OUT x LIR
where:
f = switching frequency, normally 200kHz or
?
Minimum input (battery) voltage, V IN(MIN) . This
should be taken at full load under the lowest battery
conditions. If V IN(MIN) is less than 4.2V, use an
external circuit to externally hold VL above the VL
undervoltage lockout threshold. If the minimum
input-output difference is less than 1.5V, the filter
capacitance required to maintain good AC load
regulation increases (see Low-Voltage Operation
300kHz
I OUT = maximum DC load current
LIR = ratio of AC to DC inductor current, typi-
cally 0.3; should be selected for >0.15
The nominal peak inductor current at full load is 1.15 x
I OUT if the above equation is used; otherwise, the peak
current can be calculated by:
section).
Inductor Value
I PEAK = I LOAD +
V OUT (V IN(MAX) - V OUT )
2 x f x L x V IN(MAX)
The exact inductor value is not critical and can be
freely adjusted to make trade-offs between size, cost,
and efficiency. Lower inductor values minimize size
and cost, but reduce efficiency due to higher peak-cur-
rent levels. The smallest inductor is achieved by lower-
ing the inductance until the circuit operates at the
border between continuous and discontinuous mode.
Further reducing the inductor value below this
crossover point results in discontinuous-conduction
operation even at full load. This helps lower output filter
capacitance requirements, but efficiency suffers due to
high I 2 R losses. On the other hand, higher inductor val-
ues mean greater efficiency, but resistive losses due to
extra wire turns will eventually exceed the benefit
gained from lower peak-current levels. Also, high
inductor values can affect load-transient response (see
the V SAG equation in the Low-Voltage Operation sec-
tion). The equations that follow are for continuous-con-
duction operation, since the MAX1630A family is
The inductor’s DC resistance should be low enough that
R DC x I PEAK < 100mV, as it is a key parameter for effi-
ciency performance. If a standard off-the-shelf inductor
is not available, choose a core with an LI 2 rating greater
than L x I PEAK 2 and wind it with the largest diameter
wire that fits the winding area. For 300kHz applications,
ferrite core material is strongly preferred; for 200kHz
applications, Kool-Mμ ? (aluminum alloy) or even pow-
dered iron is acceptable. If light-load efficiency is unim-
portant (in desktop PC applications, for example), then
low-permeability iron-powder cores, such as the
Micrometals type found in Pulse Engineering’s 2.1μH
PE-53680, may be acceptable even at 300kHz. For
high-current applications, shielded-core geometries,
such as toroidal or pot core, help keep noise, EMI, and
switching-waveform jitter low.
Kool-Mμ is a registered trademark of Magnetics Div., Spang & Co.
18
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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 |
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