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参数资料
| 型号： | MAX1858AEEG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 17/22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 |
| 电源电压： | 4.5 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 Buck Controllers with
Sequencing/Prebias Startup and POR
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
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
where:
I P - P = ? IN OUT ? ? OUT ?
A COMP / FB = COMP ?
? V - V ? ? V ?
? f SW L ? ? V IN ?
V
V FB
g M _ COMP
SC COMP
×
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
1 + sR COMP C COMP _ A
1 + sR COMP C COMP _ B
assuming an ideal integrator, and assuming that
C COMP_B is much less than C COMP_A :
in less output ripple voltage. Since inductor ripple current
depends on the inductor value and input voltage, the out-
put ripple voltage decreases with larger inductance and
A LX / COMP =
V LX
V COMP
=
V IN
V RAMP
increases with higher input voltages. However, the induc-
A FB / LX = = SET
V LX
V OUT S LC OUT ESR OUT + 1
+ SR C
? SET
V OUT V OUT OUT + 1
S LC
tor ripple current also impacts transient-response perfor-
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:
where V RAMP = 1V P-P :
V FB V 1 + sR ESR C OUT
2
V 1 + SR ESR C OUT
2
Therefore:
? ? V OUT ?
L ( I LOAD 1 - I LOAD 2 ) 2 ? ?
? ? ? V IN SW ?
? + t OFF ( MIN ) ?
? ?
? ? V IN - V OUT ?
2 C OUT OUT ? ? ? - t OFF ( MIN ) ?
? ? ? V IN SW ?
? ?
V SET 1 + SR ESR C OUT
× ×
V OUT
S LC
+ 1
V SAG =
V
f
f
?
?
A L ? ×
g M _ COMP 1 + SR COMP C COMP _ A
SC COMP _ A 1 + SR COMP C COMP _ B
2
OUT
×
V IN
V RAMP
where t OFF(MIN) is the minimum off-time (see the
Electrical Characteristics ), and f SW is set by R OSC (see
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
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 accuracy.
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:
is shown in Figure 9. For frequencies much lower than
Nyquist, the PWM block can be simplified to a voltage
amplifier. Connect R COMP_ and C COMP_A from COMP
to GND to compensate the loop (Figure 9). The inductor,
f Z _ COMP _ A =
1
2 π × R COMP _ C COMP _ A
output capacitor, compensation resistor, and compen-
The inductor and capacitor form a double pole at:
sation capacitors determine the loop stability. Since the
inductor and output capacitor are chosen based on per-
formance, size, and cost, select the compensation resis-
tor and capacitors to optimize control-loop stability.
f LC =
1
2 π × LC OUT
______________________________________________________________________________________
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1858AEEG+ | 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 |
| MAX1858AEEG+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 |
| MAX1858AEEG-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 |
| MAX1858EEG | 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 |
| 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 |
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