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参数资料
| 型号： | MAX1875EEG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 15/21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 Controllers with POR
As a general rule, a smaller inductor ripple current results
in less output ripple voltage. Since inductor ripple current
depends on the inductor value and input voltage, the out-
assuming an ideal integrator, and assuming that
C COMP_B is much less than C COMP_A .
put ripple voltage decreases with larger inductance and
increases with higher input voltages. However, the induc-
tor ripple current also impacts transient-response perfor-
A LX / COMP =
V LX
V COMP
=
V IN
V RAMP
A FB / LX = = SET
V OUT S LC OUT ESR OUT + 1
+ SR C
V LX
V 1 + SR ESR C OUT
? SET
V OUT V OUT S LC OUT + 1
mance, especially at low V IN - V OUT differentials. Low
inductor values allow the inductor current to slew faster,
replenishing charge removed from the output filter capac-
itors by a sudden load step. The amount of output-volt-
age sag is also a function of the maximum duty factor,
which can be calculated from the minimum off-time and
switching frequency:
for frequencies lower than Nyquist.
V FB V 1 + sR ESR C OUT
2
2
L ( I LOAD 1 - I LOAD 2 ) 2 ? ?
? ? V OUT ? ?
? ? ? V IN SW ?
? + t OFF ( MIN ) ?
? ?
? ? V IN OUT ?
V SAG =
2 C OUT OUT ? ? ? - t OFF ( MIN ) ?
g M _ COMP 1 + SR COMP C COMP _ A
1 + SR COMP COMP _ B
V SET 1 + SR ESR C OUT
× ×
V OUT
+ 1
S LC
f
- V ?
V
? ?
? ? V IN f SW ? ?
where t OFF(MIN) is the minimum off-time (see the
Electrical Characteristics ), and f SW is set by R OSC (see
Therefore:
A L ? ×
SC COMP _ A C
2
OUT
×
V IN
V RAMP
the Setting the Switching Frequency section).
Compensation
Each voltage-mode controller section employs a
transconductance error amplifier whose output is the
compensation point of the control loop. The control loop
is shown in Figure 7. For frequencies much lower than
Nyquist, the PWM block can be simplified to a voltage
For an ideal integrator this loop gain approaches infinity
at DC. In reality the g M amplifier has a finite output
impedance which imposes a finite, but large, loop gain.
It is this large loop gain that provides DC load accura-
cy. The dominant pole occurs due to the integrator, and
for this analysis, it can be approximated to occur at DC.
R COMP creates a zero at:
amplifier. Connect R COMP_ and C COMP_A from COMP
to GND to compensate the loop (see Figure 7). The
inductor, output capacitor, compensation resistor, and
f Z _ COMP _ A =
1
2 π × R COMP _ C COMP _ A
compensation capacitors determine the loop stability.
Since the inductor and output capacitor are chosen
The inductor and capacitor form a double pole at:
based on performance, size, and cost, select the com-
pensation resistor and capacitors to optimize control-
loop stability.
f LC =
1
2 π × LC OUT
To determine the loop gain (A L ), consider the gain from
FB to COMP (A COMP/FB ), from COMP to LX (A LX/COMP ),
and from LX to FB (A FB/LX ). The total loop gain is:
A L = A COMP / FB × A LX / COMP × A FB / LX
At some higher frequency the output capacitor ’ s
impedance becomes insignificant compared to its ESR,
and the LC system becomes more like an LR system,
turning a double pole into a single pole. This zero
occurs at:
A COMP / FB = ? ×
where:
V COMP g M _ COMP
V FB SC COMP
1 + sR COMP C COMP _ A
1 + sR COMP C COMP _ B
f ESR =
1
2 π × R ESR C OUT
______________________________________________________________________________________
15
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1875EEG+ | 功能描述:电压模式 PWM 控制器 Dual 180 Out PWM Step-Down 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 |
| MAX1875EEG+T | 功能描述:电压模式 PWM 控制器 Dual 180 Out PWM Step-Down 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 |
| MAX1875EEG-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 |
| MAX1875EVKIT | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX1875 MAX1876 MAX1858 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 |
| MAX1876AEEG | 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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