參數(shù)資料
型號(hào): DS232AS
廠商: DALLAS SEMICONDUCTOR
元件分類: Line Driver or Receiver
英文描述: LINE TRANSCEIVER, PDSO16
封裝: 0.300 INCH, SOIC-16
文件頁數(shù): 15/28頁
文件大小: 581K
代理商: DS232AS
MAX15023
Wide 4.5V to 28V Input, Dual-Output
Synchronous Buck Controller
22
Maxim Integrated
4) Place the second zero (fZ2) at 0.2 x fO or at fPO,
whichever is lower and calculate R1 using the fol-
lowing equation:
5) Place the third pole (fP3) at half the switching fre-
quency and calculate CCF:
6) Calculate R2 as:
MOSFET Selection
The MAX15023’s step-down controller drives two exter-
nal logic-level n-channel MOSFETs as the circuit switch
elements. The key selection parameters to choose
these MOSFETs include:
On-resistance (RDS(ON) )
Maximum drain-to-source voltage (VDS(MAX) )
Minimum threshold voltage (VTH(MIN) )
Total gate charge (Qg)
Reverse transfer capacitance (CRSS)
Power dissipation
All four n-channel MOSFETs must be a logic-level type
with guaranteed on-resistance specifications at VGS =
4.5V. For maximum efficiency, choose a high-side
MOSFET (NH_) that has conduction losses equal to the
switching losses at the typical input voltage. Ensure
that the conduction losses at minimum input voltage do
not exceed MOSFET package thermal limits, or violate
the overall thermal budget. Also, ensure that the con-
duction losses plus switching losses at the maximum
input voltage do not exceed package ratings or violate
the overall thermal budget. Ensure that the MAX15023
DL_ gate drivers can drive a low-side MOSFET (NL_).
In particular, check that the dV/dt caused by NH_ turn-
ing on does not pull up the NL_ gate through NL_’s
drain-to-gate capacitance. This is the most frequent
cause of cross-conduction problems.
Gate-charge losses are dissipated by the driver and do
not heat the MOSFET. Therefore, if the drive current is
taken from the internal LDO regulator, the power dissi-
pation due to drive losses must be checked. All
MOSFETs must be selected so that their total gate
charge is low enough; therefore, VCC can power all four
drivers without overheating the IC:
where QG_TOTAL is the sum of the gate charges of all
four MOSFETs.
Power Dissipation
Device’s maximum power dissipation depends on the
thermal resistance from the die to the ambient environ-
ment and the ambient temperature. The thermal resis-
tance depends on the device package, PCB copper
area, other thermal mass, and airflow.
The power dissipated into the package (PT) depends on
the supply configuration (see the
Typical Application
Circuits). It can be calculated using the following equation:
PT = VIN x IIN
For the circuits of Figures 7 and 8:
PT = VCC x (IIN + IVCC)
where VIN and VCC are the voltages at the respective
pins, IIN is the current at the input of the internal LDO
(IIN is practically zero for the circuits of Figures 7 and
8), IVCC is the current consumed by the internal core
and drivers when the internal regulator is unused for 5V
supply operation (IN = VCC). See the corresponding
Typical Operating Characteristics for the typical curves
of IIN and IVCC current consumption vs. operating fre-
quency at various load capacitance values.
PV
Q
f
DRIVE
IN
G TOTAL
SW
×
_
R
V
VV
R
FB
OUT
FB
21
C
fR
C
CF
F
SW
F
=
××
×
()
20 5
1
π
.
R
fC
R
ZI
I
1
2
1
2
=
××
π
VREF
gm
R1
R2
VOUT
RI
COMP
CI
CCF
RF
CF
Figure 5. Type III Compensation Network
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS232AS/T&R 制造商:Maxim Integrated Products 功能描述:IC TXRX DUAL RS-232 5V 16-SOIC
DS232AS/T&R 功能描述:RS-232接口集成電路 RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝:
DS232AS+ 功能描述:RS-232接口集成電路 Dual RS-232 Transmitter/Receiver RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝:
DS232AS+T&R 制造商:Maxim Integrated Products 功能描述:IC TXRX DUAL RS-232 5V 16-SOIC
DS232AS+T&R 功能描述:RS-232接口集成電路 RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝: