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參數(shù)資料
| 型號： | MAX1636 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Low-Voltage, Precision Step-Down Controller for Portable CPU Power |
| 中文描述： | 低電壓、高精度降壓型控制器，用于便攜式CPU電源 |
| 文件頁數(shù)： | 13/24頁 |
| 文件大?。?/td> | 219K |
| 代理商： | MAX1636 |
M
Low-Voltage, Prec ision S tep-Down
Controller for Portable CPU Power
______________________________________________________________________________________
13
by reducing the effective frequency, subsequently
reducing switching losses. It forces the peak inductor
current to ramp to 30% of the full current limit, deliver-
ing extra energy to the output and allowing subsequent
cycles to be skipped. Idle Mode transitions seamlessly
to fixed-frequency PWM operation as load current
increases.
With
SKIP
= high, the controller always operates in
fixed-frequency PWM mode for lowest noise. Each
pulse from the oscillator sets the main PWM latch that
turns on the high-side switch for a period determined
by the duty factor (approximately V
OUT
/ V
IN
). As the
high-side switch turns off, the synchronous rectifier
latch sets; 60ns later, the low-side switch turns on. The
low-side switch stays on until the beginning of the next
clock cycle.
In PWM mode, the controller operates as a fixed-fre-
quency, current-mode controller in which the duty fac-
tor is set by the input/output voltage ratio. The
current-mode feedback system regulates the peak
inductor current value as a function of the output volt-
age error signal. In continuous-conduction mode, the
average inductor current is nearly the same as the
peak current, so the circuit acts as a switch-mode
transconductance amplifier. This pushes the second
output LC filter pole, normally found in a duty-factor-
controlled (voltage-mode) PWM, to a higher frequency.
To preserve inner-loop stability and eliminate regenera-
tive inductor current “staircasing,” a slope-compensa-
tion ramp is summed into the main PWM comparator to
make the apparent duty factor less than 50%.
The relative gains of the voltage-sense and current-
sense inputs are weighted by the values of current
sources that bias four differential input stages in the
main PWM comparator (Figure 4). The voltage sense
into the PWM has been conditioned by an integrated
component of the feedback voltage, yielding excellent
DC output voltage accuracy. See the Output Voltage
Accuracy section for more information.
S ync hronous Rec tifier Driver (DL)
Synchronous rectification reduces conduction losses in
the rectifier by shunting the normal Schottky catch
diode with a low-resistance MOSFET switch. Also, the
synchronous rectifier ensures proper start-up of the
boost gate-driver circuit. If the synchronous power
MOSFET is omitted for cost or other reasons, replace it
with a small-signal MOSFET, such as a 2N7002.
If the circuit is operating in continuous-conduction
mode, the DL drive waveform is simply the comple-
ment of the DH high-side-drive waveform (with con-
trolled dead time to prevent cross-conduction or
“shoot-through”). In discontinuous (light-load) mode,
the synchronous switch is turned off as the inductor
current falls through zero.
FB
REF
CSH
CSL
CC
SLOPE COMPENSATION
V
CC
I2
R1
R2
TO PWM
LOGIC
OUTPUT DRIVER
UNCOMPENSATED
HIGH-SPEED
LEVEL TRANSLATOR
AND BUFFER
I1
I3
I4
V
BIAS
Figure 4. Main PWM Comparator Functional Diagram
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PDF描述 |
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| MAX1636EAP | Low-Voltage, Precision Step-Down Controller for Portable CPU Power |
| MAX1637 | Miniature, Low-Voltage, Precision Step-Down Controller |
| MAX1637EEE | Miniature, Low-Voltage, Precision Step-Down Controller |
| MAX1638 | High-Speed Step-Down Controller with Synchronous Rectification for CPU Power |
| MAX1638EAG | High-Speed Step-Down Controller with Synchronous Rectification for CPU Power |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1636CPUEVKIT | 制造商:Maxim Integrated Products 功能描述:LOW VOLTAGE, PRECISION STEP DOWN CONTROLLER F - Bulk |
| MAX1636EAP | 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 |
| MAX1636EAP+ | 功能描述:DC/DC 開關(guān)控制器 Precision Step-Down for Portable CPU Pwr 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 |
| MAX1636EAP+T | 功能描述:DC/DC 開關(guān)控制器 Precision Step-Down for Portable CPU Pwr 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 |
| MAX1636EAP-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 |
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