参数资料
型号: MAX1980ETP+
厂商: Maxim Integrated Products
文件页数: 20/33页
文件大小: 0K
描述: IC REG CTRLR BUCK PWM 20-TQFN
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 60
系列: Quick-PWM™
PWM 型: 控制器
输出数: 1
频率 - 最大: 550kHz
占空比: 50%
电源电压: 4.5 V ~ 5.5 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: 0°C ~ 85°C
封装/外壳: 20-WQFN 裸露焊盘
包装: 管件
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
SLAVE
CONTROLLER
MASTER
CONTROLLER
ILIM
R C
C REF
REF
V ITHM ( HIGH ) =
1 ? R B ?
? ?
10 ? R A + R B ? V REF
R D
MAX1980
MAX1718
V ITHM ( LOW ) =
1 ? R B // R LIMIT ?
? ?
10 ? R A + ( R B // R LIMIT ) ?
V REF
R A
LIMIT
R LIMIT
C LIMIT
R B
ILIM
V ITHS =
1 ? R D ?
? ?
10 ? R C + R D ?
V REF
Figure 5. Setting the Adjustable Current Limits
≤ R D ≤
R C = ? ?
? ? 1 ? R D
≤ R B ≤
R A = ? ?
? ? 1 ? R B
1 + ? A B ? ≥
where V ITHM , the master ’ s current-limit threshold, is typ-
ically 1/10th the voltage seen at the master ’ s ILIM input
(V ITHM = 0.1 ? V LIM(MASTER) , see the master con-
troller ’ s data sheet). Connect a resistive voltage-divider
from the master controller ’ s internal reference to GND,
with the master ’ s ILIM input connected to the center tap
(Figure 5). Use 1% tolerance resistors in the divider with
10μA to 20μA DC bias current to prevent significant
errors due to the ILIM pin ’ s input current:
V ILIM ( MASTER ) V ILIM ( MASTER )
20 μ A 10 μ A
? ? V REF ( MASTER ) ? ?
? ?
? ? V ILIM ( MASTER ) ? ?
Configure the slave controller so its LIMIT output begins
to roll off after the master current-limit threshold occurs:
voltage lowers the sense resistor ’ s power dissipation,
but this also increases the relative measurement error:
V ILIM ( SLAVE ) V ILIM ( SLAVE )
20 μ A 10 μ A
? ? V REF ( MASTER ) ? ?
? ?
? ? V ILIM ( SLAVE ) ? ?
Now, set the current-limit adjustment ratio (A ADJ =
V ITHM(HIGH) /V ITHM(LOW) ) greater than the maximum to
minimum on-resistance ratio (A RDS = R DS(ON)(MAX) /
R DS(ON)(MIN) ):
A ADJ ≥ A ROS
? R // R ? R DS ( ON )( MAX )
? R LIMIT ? R DS ( ON )( MIN )
V ITHS ≥ R CM ?
+ ? I INDUCTOR ?
? V ITHM ( HIGH )
? R DS ( ON )( MAX )
?
?
Increasing A ADJ improves the master ’ s current-limit
accuracy but also increases the current limit ’ s noise
sensitivity. Therefore, R LIMIT may be selected using the
following equation:
where V ITHS , the slave ’ s current-limit threshold, is pre-
cisely one-tenth the voltage seen at the slave ’ s ILIM
input (V ITHS = 0.1 ? V ILIM(SLAVE) ). Connect a second
resistive voltage-divider from the master controller ’ s
R LIMIT ≤
( R A // R B ) R DS ( ON )( MIN )
R DS ( ON )( MAX ) ? R DS ( ON )( MIN )
internal reference to GND, with the slave ’ s ILIM input
connected to the center tap (Figure 5). The external
Finally, verify that the total load on the master ’ s refer-
ence does not exceed 50μA:
? ? ? V REF ?
I BIAS ( TOTAL ) = ?
? + ?
adjustment range of 400mV to 1.5V corresponds to a
current-limit threshold of 40mV to 150mV. Use 1% toler-
ance resistors in the divider with 10μA to 20μA DC bias
current to prevent significant errors due to the ILIM
pin ’ s input current. Reducing the current-limit threshold
V REF
?
? R A + ( R B // R LIMIT ) ? ? R C + R D ?
≤ 50 μ A
20
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MAX1980ETP+TG075 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
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