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參數(shù)資料
| 型號： | MAX1980ETP |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Quick-PWM Slave Controller with Driver Disable for Multiphase DC-DC Converter |
| 中文描述： | SWITCHING CONTROLLER, 550 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封裝： | 5 X 5 MM, 0.80 MM HEIGHT, THIN, QFN-20 |
| 文件頁數(shù)： | 16/33頁 |
| 文件大?。?/td> | 1153K |
| 代理商： | MAX1980ETP |
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M
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
16
______________________________________________________________________________________
When the slave controller
’
s current-limit voltage (V
ILIM
) is
set through a resistive-divider between the master con-
troller
’
s reference and GND (see the
Current-Limit
Circuitry
section), the MAX1980 automatically enters low-
power standby mode when the master controller shuts
down. As the master
’
s reference powers down, the resis-
tive-divider pulls ILIM below 250mV, automatically acti-
vating the MAX1980
’
s low-power standby mode.
Current-Limit Circuitry
When the master
’
s inductor current exceeds its valley
current limit, the master extends its off time by forcing
DL high until the inductor current falls below the current-
limit threshold. Without a transition on the master
’
s low-
side gate driver, the slave cannot initiate a new on-time
pulse so the slave
’
s inductor current ramps down as
well, maintaining the current balance. Therefore, the
slave
’
s valley current limit only needs to protect the
slave controller if the current balance circuitry or the
master current limit fails. The slave
’
s ILIM input voltage
should be selected to properly adjust the master
’
s cur-
rent-limit threshold.
Dual-Mode ILIM Input
The current-limit input (ILIM) features dual-mode opera-
tion, serving as both the standby mode control input
and the current-limit threshold adjustment. The slave
controller enters a low-power standby mode when the
ILIM voltage (V
ILIM
) is pulled below 250mV. For ILIM
voltages from 400mV to 1.5V, the current-limit threshold
voltage is precisely 0.1
V
ILIM
. The current-limit volt-
age may be accurately set with a resistive voltage-
divider between the master controller
’
s reference and
GND, allowing the MAX1980 to automatically enter the
low-power standby mode.
Slave Current Limit
The slave current-limit circuit employs a unique
“
valley
”
current-sensing algorithm. If the current-sense signal is
above the current-limit threshold, the MAX1980 will not ini-
tiate a new cycle (Figure 3). The actual peak inductor cur-
rent is greater than the current-limit threshold by an
amount equal to the inductor ripple current. Therefore, the
exact current-limit characteristic and maximum load
capability are a function of the current-limit threshold,
inductor value, and input voltage. The reward for this
uncertainty is robust, overcurrent sensing. When com-
bined with master controllers that contain output under-
voltage protection circuits, this current-limit method is
effective in almost every circumstance.
There also is a negative current limit that prevents
excessive reverse inductor currents when V
OUT
is sink-
ing current. The negative current-limit threshold is set to
approximately 150% of the positive current-limit thresh-
old, and tracks the positive current limit when ILIM is
adjusted.
The MAX1980 uses CS+ and CS- to differentially measure
the current across an external sense resistor (R
CS
) con-
nected between the inductor and output capacitors. This
configuration provides precise current balancing, current
limiting, and voltage positioning with a 1% current-sense
resistor. Reducing the sense voltage decreases power
dissipation but increases the relative measurement error.
Carefully observe the PC board layout guidelines to
ensure that noise and DC errors don
’
t corrupt the cur-
rent-sense signals measured at CS+ and CS-. The IC
should be mounted relatively close to the current-sense
resistor with short, direct traces making a Kelvin sense
connection.
Master Current-Limit Adjustment (LIMIT)
The Quick-PWM controllers that may be used as the
master controller typically use the low-side MOSFET
’
s
on-resistance as its current-sense element. This depen-
dence on a loosely specified resistance with a large tem-
perature coefficient causes inaccurate current limiting.
As a result, high current-limit thresholds are needed to
Table 4. Operating Mode Truth Table
DD
ILIM
DL
MODE
COMMENTS
V
CC
High
(> 0.25V)
Switching
Normal
Operation
Low-noise, fixed-frequency, PWM operation. The inductor current
reverses with light loads.
GND
High
(> 0.25V)
Low
Driver
Disable
Li g ht l oad si ng e- p hase op er ati on. The M AX 1980 d sab es the d ver s
b y for ci ng D L and D H l ow effecti vel y d sab ng the sl ave contr ol er
X
GND
(< 0.25V)
Low
Standby
Low-power, standby mode (I
CC
+ I
DD
= 20μA typ). DL and DH
forced low, and the PWM controller disabled. However, the bias and
fault-protection circuitry remain active so the MAX1980 can
continuously monitor the ILIM input.
X = Don
’
t Care
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1980ETP+ | 功能描述:DC/DC 開關(guān)控制器 PWM Slave Controller w/Driver Disable RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX1980ETP+T | 功能描述:DC/DC 開關(guān)控制器 PWM Slave Controller w/Driver Disable RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX1980ETP+TG075 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1980ETP-T | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| 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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