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| 型号： | MAX1858EEG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/21页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 24-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 660kHz |
| 占空比： | 90% |
| 电源电压： | 4.75 V ~ 23 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： | 24-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
Dual 180° Out-of-Phase PWM Step-Down
Controller with Power Sequencing and POR
Connect ILIM_ to V L for the default 100mV (typ) current-
limit threshold. For an adjustable threshold, connect a
resistor (R ILIM _) from ILIM_ to GND. The relationship
between the current-limit threshold (V ITH _) and R ILIM _ is:
OUT_
R_A
REF
R_C
R ILIM _ =
V ITH _
0 . 5 μ A
FB_
FB_
where R ILIM _ is in ? and V ITH _ is in V. An R ILIM resis-
tance range of 100k ? to 600k ? corresponds to a current-
limit threshold of 50mV to 300mV. When adjusting the
current limit, 1% tolerance resistors minimizes error in the
current-limit threshold. For foldback current limit, a resis-
tor (R FBI ) is added from ILIM pin to output. The value of
MAX1858
V OUT_ > 1V
R_B
MAX1858
V OUT_ < 1V
R_A
OUT_
R FBI =
R ILIM =
10 × V ITH ( 1 - P FB ) × R FBI
[ V OUT - 10 × V ITH ( 1 - P FB )]
I RMS = I LOAD
V RIPPLE ( C ) =
I P - P = ? IN OUT ? ? OUT ?
R ILIM and R FBI can then be calculated as follows:
First select the percentage of foldback (P FB ) from 15%
to 30%, then:
P FB × V OUT
5 × 10 - 6 ( 1 - P FB )
and
Input Capacitor
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit ’ s switching.
The input capacitor must meet the ripple current
requirement (I RMS ) imposed by the switching currents
as defined by the following equation:
V OUT ( V IN - V OUT )
V IN
I RMS has a maximum value when the input voltage
equals twice the output voltage (V IN = 2V OUT ), so
I RMS(MAX) = I LOAD / 2. For most applications, nontanta-
lum capacitors (ceramic, aluminum, polymer, or
OSCON) are preferred at the input due to their robust-
ness with high inrush currents typical of systems that can
be powered from very low impedance sources.
Additionally, two (or more) smaller-value low-ESR capaci-
tors can be connected in parallel for lower cost. Choose
an input capacitor that exhibits less than +10 ° C tem-
perature rise at the RMS input current for optimal long-
term reliability.
Figure 6. Adjustable Output Voltage
Output Capacitor
The key selection parameters for the output capacitor
are capacitance value, ESR, and voltage rating. These
parameters affect the overall stability, output ripple volt-
age, and transient response. The output ripple has two
components: variations in the charge stored in the out-
put capacitor, and the voltage drop across the capaci-
tor ’ s ESR caused by the current flowing in to and out of
the capacitor.
V RIPPLE ? V RIPPLE ( ESR ) + V RIPPLE ( C )
The output voltage ripple as a consequence of the ESR
and output capacitance is:
V RIPPLE ( ESR ) = I P - P R ESR
I P - P
8 C OUT f SW
? V - V ? ? V ?
? f SW L ? ? V IN ?
where I P-P is the peak-to-peak inductor current (see the
Inductor Selection section). These equations are suitable
for initial capacitor selection, but final values should be
verified by testing in a prototype or evaluation circuit.
As a general rule, a smaller inductor ripple current
results in less output ripple voltage. Since inductor rip-
ple current depends on the inductor value and input
voltage, the output ripple voltage decreases with larger
inductance and increases with higher input voltages.
However, the inductor ripple current also impacts tran-
sient-response performance, especially at low
V IN - V OUT differentials. Low inductor values allow the
inductor current to slew faster, replenishing charge
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1858EEG+ | 功能描述:电压模式 PWM 控制器 Dual 180 Out Buck Controllers 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 |
| MAX1858EEG+T | 功能描述:电压模式 PWM 控制器 Dual 180 Out Buck Controllers 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 |
| MAX1858EEG-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 |
| MAX1858EVKIT | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX1858 MAX1875 MAX1876 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 |
| MAX185ACNG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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