参数资料
型号: MAX1876EEG+
厂商: Maxim Integrated Products
文件页数: 16/21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:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
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
GAIN = +V IN /V RAMP FOR
FREQUENCIES LOWER
P
DH
N
THAN NYQUIST
W
L
V OUT
L
COMP_
V C
g M_GROUP
M
DL
FB
N
LX
R ESR
C OUT
=
COMP_
g M_GROUP
FB
LX
R ESR
C OUT
R COMP_
C COMP_A
C COMP_B
V SET
R COMP_
C COMP_A
C COMP_B
V SET
Figure 7. Fixed-Frequency Voltage-Mode Control Loop
× SET
A final pole is added using C COMP_B to reduce the
gain and attenuate noise after crossover. This pole
(f COMP_B ) occurs at:
f CO = GBW =
V IN
V RAMP
V
V OUT
f COMP _ B =
1
2 π × R COMP C COMP _ B
×
g M _ COMP × R COMP × R ESR
2 π × L
2 × LC OUT
Figure 8 shows a Bode plot of the poles and zeros in
their relative locations.
Near crossover the following approximations can be
made to simplify the loop-gain equation:
? R COMP has much higher impedance than C COMP .
This is true if, and only if, crossover occurs above
f Z_COMP_A . If this is true, C COMP_A can be ignored
(as a short to ground).
? R ESR is much higher impedance than C OUT . This is
true if, and only if, crossover occurs well after the out-
put capacitor ’ s ESR zero. If this is true, C OUT
becomes an insignificant part of the loop gain and can
be ignored (as a short to ground).
? C COMP_B is much higher impedance than R COMP
To ensure stability, select R COMP to meet the following
criteria:
? Unity-gain crossover must occur below 1/5th of the
switching frequency.
? For reasonable phase margin using type 1 compen-
sation, f CO must be larger than 5 ? f ESR .
Choose C COMP_A so that f Z_COMP_A equals half f LC
using the following equation:
C COMP _ A =
R COMP
Choose C COMP_B so that f COMP_B occur at 3 times f CO
using the following equation:
( )
and can be ignored (as an open circuit). This is true
if, and only if, crossover occurs far below f COMP_B .
The following loop gain equation can be found by using
these previous approximations with Figure 7:
C COMP _ B =
1
2 π × 3 × f CO × R COMP
MOSFET Selection
× ×
A L ?
V IN
V RAMP
V SET
V OUT
g M _ COMP × R COMP × R ESR
sL
The MAX1875/MAX1876s ’ step-down controller drives
two external logic-level N-channel MOSFETs as the cir-
cuit switch elements. The key selection parameters are:
Setting the loop gain to 1 and solving for the crossover
frequency yields:
? On-resistance (R DS(ON) )
? Maximum drain-to-source voltage (V DS(MAX) )
16
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MAX1876EEG+ 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
MAX1876EEG+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
MAX1876EEG-G05 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
MAX1876EEG-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
MAX1876EEG-TG05 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