參數(shù)資料
型號(hào)： MAX1791
廠商： Maxim Integrated Products, Inc.
英文描述： High-Efficiency, 10-Pin レMAX, Step-Down Controllers for Notebooks
中文描述： 高效率、10引腳µMAX、降壓型控制器，用于筆記本電腦
文件頁(yè)數(shù)： 13/20頁(yè)
文件大?。?/td> 391K
代理商： MAX1791
M
High-Efficiency, 10-Pin μMAX, Step-Down
Controllers for Notebooks
______________________________________________________________________________________
13
rated for +0.5A, -0.9A source/sink capability and
swings from VL to GND.
The internal pulldown transistor that drives DL low is
robust, with a 1
typical on-resistance. This helps pre-
vent DL from being pulled up during the fast rise time of
the inductor node, due to capacitive coupling from the
drain to the gate of the low-side synchronous-rectifier
MOSFET. However, for high-current applications, some
combinations of high-and low-side FETS may cause
excessive gate-drain coupling, which can lead to poor
efficiency, EMI, and shoot-through currents.
An adaptive dead-time circuit monitors the DL output
and prevents the high-side FET from turning on until DL
is fully turned off. The dead time at the other edge (DH
turning off) is determined by a fixed 35ns (typ) internal
delay.
Low-Side Current-Limit Sensing (ILIM)
The current-limit circuit employs a unique
“
valley
”
cur-
rent-sensing algorithm that uses the on-state resistance
of the low-side MOSFET as a current-sensing element.
If the current-sense signal is below the current-limit
threshold (-100mV from CS to GND), the PWM is not
allowed to initiate a new cycle (Figure 7). The actual
peak current 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 MOSFET
on-resistance, inductor value, and battery voltage.
If greater current-limit accuracy is desired, CS must be
connected to the junction of the low-side switch source
and a current-sense resistor to GND. The current limit
will be 0.1V/R
SENSE
, and the accuracy will be ±10%.
A resistive voltage-divider from the inductor
’
s switching
mode to ground can be used to adjust the current-limit
sense voltage that appears at CS (Figure 8). Keep the
impedance at this mode low to avoid errors at CS.
POR and Soft-Start
Power-on reset (POR) occurs when V
BATT
rises above
approximately 2V, resetting the fault latch and soft-start
counter and preparing the PWM for operation. UVLO
circuitry inhibits switching until V
VP
rises above 4.1V,
whereupon an internal digital soft-start timer begins to
ramp up the maximum allowed current limit. The ramp
occurs in five steps: 20%, 40%, 60%, 80%, and 100%;
100% current is available after approximately 1.7ms.
Output Undervoltage Protection
The output UVLO function is similar to foldback current
limiting but employs a timer rather than a variable cur-
rent limit. The output undervoltage protection is
enabled 20ms after POR or when coming out of shut-
down. If the output is under 70% of the nominal value,
Figure 6. Pulse-Skipping/Discontinuous Crossover Point
I
I
LOAD
= I
PEAK
/2
ON-TIME
0
TIME
I
PEAK
L
V
BATT
- V
OUT
i
t
=
Figure 7. “Valley” Current-Limit Threshold Point
I
I
LIMIT
I
LOAD
0
TIME
I
PEAK
Figure 8. Using a Resistive Voltage-Divider to Adjust Current-
Limit Sense Voltage to 200mV
CS
DH
DL
V
P
MAX1762
MAX1791
1.0k
V
OUT
1.0k
相關(guān)PDF資料
PDF描述
MAX1762 Replaced by TMS320VC5506 : Digital Signal Processor 100-LQFP
MAX1762-MAX1791 High-Efficiency, 10-Pin レMAX, Step-Down Controllers for Notebooks
MAX1762EUB Replaced by TMS320C2802 : 16-bit, 5V fixed point DSP 132-BQFP -40 to 125
MAX1791EUB High-Efficiency, 10-Pin レMAX, Step-Down Controllers for Notebooks
MAX1792 500mA Low-Dropout Linear Regulator in レMAX
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX17911EVKIT+ 制造商:Maxim Integrated Products 功能描述:EVKIT - Boxed Product (Development Kits)
MAX17911GTL+ 制造商:Maxim Integrated Products 功能描述:AMD SVI1 CPU CONTROLLER 3PHASE - Rail/Tube
MAX1791EUB 功能描述:DC/DC 開(kāi)關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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
MAX1791EUB+ 功能描述:DC/DC 開(kāi)關(guān)控制器 Step-Down for Notebook RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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
MAX1791EUB+ 制造商:Maxim Integrated Products 功能描述:CONTROLLER ((NW))
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