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參數(shù)資料
| 型號(hào)： | 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)： | 27/33頁 |
| 文件大小： | 1153K |
| 代理商： | MAX1980ETP |
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M
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
______________________________________________________________________________________
27
One-Stage (Battery Input) vs.
Two-Stage (5V Input) Applications
The MAX1980 can be used with a direct battery con-
nection (one stage) or can obtain power from a regulat-
ed 5V supply (two-stage). Each approach has
advantages, and careful consideration should go into
the selection of the final design.
The one-stage approach offers smaller total inductor
size and fewer capacitors overall due to the reduced
demands on the 5V supply. Due to the high input volt-
age, the one-stage approach requires lower DC input
currents, reducing input connection/bus requirements
and power dissipation due to input resistance. The
transient response of the single stage is better due to
the ability to ramp the inductor current faster. The total
efficiency of a single stage is better than the two-stage
approach.
The two-stage approach allows flexible placement due
to smaller circuit size and reduced local power dissipa-
tion. The power supply can be placed closer to the
CPU for better regulation and lower I
2
R losses from PC
board traces. Although the two-stage design has slow-
er transient response than the single stage, this can be
offset by the use of a voltage-positioned converter.
Ceramic Output Capacitor Applications
Ceramic capacitors have advantages and disadvan-
tages. They have ultra-low ESR and are noncom-
bustible, relatively small, and nonpolarized. However,
they are also expensive and brittle, and their ultra-low
ESR characteristic can result in excessively high ESR
zero frequencies. In addition, their relatively low capac-
itance value can cause output overshoot when step-
ping from full-load to no-load conditions, unless a small
inductor value is used (high switching frequency), or
there are some bulk tantalum or electrolytic capacitors
in parallel to absorb the stored inductor energy. In
some cases, there may be no room for electrolytics,
creating a need for a DC-DC design that uses nothing
but ceramics.
The MAX1980 can take full advantage of the small size
and low ESR of ceramic output capacitors in a voltage-
positioned circuit. The addition of the positioning resis-
tor increases the ripple at FB, lowering the effective
ESR zero frequency of the ceramic output capacitor.
Output overshoot (V
SOAR
) determines the minimum
output capacitance requirement (see the
Output
Capacitor Selection
section). Often the switching fre-
quency is increased to 550kHz, and the inductor value
is reduced to minimize the energy transferred from
inductor to capacitor during load-step recovery. The
efficiency penalty for operating at 550kHz is about 3%
when compared to the 300kHz circuit, primarily due to
the high-side MOSFET switching losses.
PC Board Layout Guidelines
Careful PC board layout is critical to achieve low
switching losses and clean, stable operation. The
switching power stage requires particular attention
(Figure 10). If possible, mount all of the power compo-
nents on the top side of the board with their ground ter-
minals flush against one another. Follow these
guidelines for good PC board layout:
1) Keep the high-current paths short, especially at the
ground terminals. This is essential for stable, jitter-
free operation
2) Connect all analog grounds to a separate solid
copper plane, which connects to the GND pin of
the MAX1980. This includes the V
CC
bypass capac-
itor, COMP components, and the resistive-divider
connected to ILIM.
3) The master controller also should have a separate
analog ground. Return the appropriate noise sensi-
tive components to this plane. Since the reference
in the master is sometimes connected to the slave,
it may be necessary to couple the analog ground in
the master to the analog ground in the slave to pre-
vent ground offsets. A low value (
≤
10
) resistor is
sufficient to link the two grounds.
4) Keep the power traces and load connections short.
This is essential for high efficiency. The use of thick
copper PC boards (2oz vs. 1oz) can enhance full-
load efficiency by 1% or more. Correctly routing PC
board traces is a difficult task that must be
approached in terms of fractions of centimeters,
where a single m
of excess trace resistance caus-
es a measurable efficiency penalty.
5) Keep the high-current gate-driver traces (DL, DH,
LX, and BST) short and wide to minimize trace
resistance and inductance. This is essential for
high-power MOSFETs that require low-impedance
gate drivers to avoid shoot-through currents.
6) CS+, CS-, CM+, and CM- connections for current
limiting and balancing must be made using Kelvin
sense connections to guarantee the current-sense
accuracy.
7) When trade-offs in trace lengths must be made, it
’
s
preferable to allow the inductor charging path to be
made longer than the discharge path. For example,
it
’
s better to allow some extra distance between the
input capacitors and the high-side MOSFET than to
allow distance between the inductor and the low-
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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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