- 您现在的位置：买卖IC网 > PDF目录357567 > ADM1051AJRZ (ANALOG DEVICES INC) DUAL SWITCHING CONTROLLER, PDSO8 PDF资料下载
参数资料
| 型号： | ADM1051AJRZ |
| 厂商： | ANALOG DEVICES INC |
| 元件分类： | 稳压器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, PDSO8 |
| 封装： | SOIC-8 |
| 文件页数： | 9/10页 |
| 文件大小： | 176K |
| 代理商： | ADM1051AJRZ |
REV. 0
ADM1051/ADM1051A
–9–
SUPPLY DECOUPLING
The supply to the drain of an external MOSFET should be
decoupled as close as possible to the drain pin of the device, with
at least 100
μ
F to ground. The output from the source of the
MOSFET should be decoupled as close as possible to the source
pin of the device. Decoupling capacitors should be chosen to have
a low Equivalent Series Resistance (ESR), typically 50 m
or
lower. With the MOSFETs specified, and two 100
μ
F capacitors
in parallel, the circuit will be stable for load currents up to 2 A.
The V
CC
pin of the ADM1051/ADM1051A should be decoupled
with at least 1
μ
F to ground, connected as close as possible to
the V
CC
and GND pins.
In practice, the amount of decoupling required will depend on
the application. PC motherboards are notoriously noisy envi-
ronments, and it may be necessary to employ distributed decoupling
to achieve acceptable noise levels on the supply rails.
SHDN1
V
CC
ADM1051
SHDN2
1 F
LEAVE OPEN OR
CONNECT TO
LOGIC SIGNALS
IF SHUTDOWN
REQUIRED
PHD55N03LT
FORCE 2
SENSE 2
100 F
2 100 F
V
OUT1
FORCE 1
SENSE 1
V
IN
3.3V
12V
MTD3055VL
100 F
2 100 F
V
OUT2
V
IN
3.3V
Figure 6. Typical ADM1051 Application Circuit
CHOICE OF MOSFET
As previously discussed, the load current at which an output goes
into Hiccup Mode depends on the on resistance of the external
MOSFET. If the on resistance is too low, this current may be
very high; if the on resistance is high, the trip current may be
lower than the maximum required load current. For the primary
application of AGP and ICH power supplies and bus termina-
tion on personal computer motherboards, devices with very
low on resistance, such as the PHD55N03LT from Philips,
or the SUB60N06-18 from Siliconix, are suitable. For Channel 2,
suitable devices are the MTD3055VL from Motorola and the
PHB11N06LT from Philips.
POWERING SUPPLY SEQUENCING
Some I/O control hub chipsets have power-supply sequencing
requirements, which dictate that the 1.818 V supply must never
be more than 2 V below the 3.3 V supply. This requirement can
be met using the ADM1051A, as shown in Figure 7. In this
circuit, V
CC
is supplied from the 5 V standby rail (5 VSB) and
from the 12 V rail via Schottky diodes. 5 VSB is always present
when ac power is supplied to the system, so the ADM1051A is
powered up, but V
CC
is below the POR threshold. When the main
power supplies are turned on, the Channel 2 output will rise at
the same rate as the 3.3 V rail until it regulates at 1.818 V. The
12 V supply will take over from 5 VSB when it exceeds the 5 VSB
rail, and Channel 1 will then be subject to the POR delay. This
ensures that Channel 2 can never be more than 2 V below
Channel 1.
SHDN1
V
CC
ADM1051A
SHDN2
0.1
F
PHD55N03LT
FORCE 2
SENSE 2
100 F
2 100 F
V
OUT1
FORCE 1
SENSE 1
V
IN
3.3V
12V
MTD3055VL
100 F
2 100 F
V
OUT2
V
IN
3.3V
3.3V
10k
BAT45C
BAT45C
5VSB
Figure 7. Typical ADM1051A Application Circuit
THERMAL CONSIDERATIONS
Heat generated in the external MOSFET must be dissipated
and the junction temperature of the device kept within accept-
able limits. The power dissipated in the device is, of course, the
drain-source voltage multiplied by the load current. The required
thermal resistance to ambient is given by
J
A
=
T
J
(
MAX
)
–
T
AMB
(
MAX
)
/(
V
DS
(
MAX
)
×
I
OUT
(
MAX
)
)
Surface-mount MOSFETs, such as those specified, must rely on
heat conduction through the device leads and the PCB. One
square inch of copper (645 sq. mm) gives a thermal resistance
of around 60
°
C/W for an SOT-223 surface-mount package and
80
°
C/W for an SO-8 surface-mount package.
For high power dissipation that can be accommodated by a
surface-mount package, D
2
PAK or TO-220 devices are rec-
ommended. These should be mounted on a heat sink with a
thermal resistance low enough to maintain the required maxi-
mum junction temperature.
相关PDF资料 |
PDF描述 |
|---|---|
| ADP06 | PIANO DIP SWITCH-6SWITCHES, SPST, MOMENTARY,THROUGH HOLE-STRAIGHT |
| ADP08SA | PIANO DIP SWITCH-8SWITCHES, SPST, MOMENTARY,SURFACE MOUNT-STRAIGHT |
| ADP1109AR-12-REEL | 1.2 A SWITCHING REGULATOR, 120 kHz SWITCHING FREQ-MAX, PDSO8 |
| ADPA05 | PIANO DIP SWITCH-5SWITCHES, SPST, MOMENTARY,THROUGH HOLE-STRAIGHT |
| ADS-929MC | |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ADM1051AJRZ-REEL | 制造商:Analog Devices 功能描述:DC DC CNTRLR DUAL-OUT STEP DOWN 12V 8SOIC N - Tape and Reel |
| ADM1051AJRZ-REEL7 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| ADM1051JR | 制造商:Analog Devices 功能描述:DC DC Cntrlr Dual-OUT Step Down 12V Input 8-Pin SOIC N 制造商:Analog Devices 功能描述:DC DC CNTRLR DUAL-OUT STEP DOWN 12V 8SOIC - Bulk 制造商:Rochester Electronics LLC 功能描述:DUAL BUS TERMINATOR - Bulk |
| ADM1051JR-REEL | 制造商:Analog Devices 功能描述:DC DC CNTRLR DUAL-OUT STEP DOWN 12V 8SOIC N - Tape and Reel 制造商:Rochester Electronics LLC 功能描述:DUAL BUS TERMINATOR - Tape and Reel |
| ADM1051JR-REEL7 | 制造商:Analog Devices 功能描述:DC DC Cntrlr Dual-OUT Step Down 12V Input 8-Pin SOIC N T/R 制造商:Analog Devices 功能描述:DC DC CNTRLR DUAL-OUT STEP DOWN 12V 8SOIC N - Tape and Reel |
发布紧急采购，3分钟左右您将得到回复。