- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄374021 > ADP3310AR-3 (ANALOG DEVICES INC) Circular Connector Cable Assembly; Connector Type A:Circular Plug; Connector Type B:Stripped End Leads; Cable Length:10ft RoHS Compliant: Yes PDF資料下載
參數(shù)資料
| 型號(hào)： | ADP3310AR-3 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 模擬信號(hào)調(diào)理 |
| 英文描述： | Circular Connector Cable Assembly; Connector Type A:Circular Plug; Connector Type B:Stripped End Leads; Cable Length:10ft RoHS Compliant: Yes |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO8 |
| 封裝： | SO-8 |
| 文件頁數(shù)： | 6/8頁 |
| 文件大小： | 120K |
| 代理商： | ADP3310AR-3 |
ADP3310
–6–
REV. A
APPLICATION INFORMATION
The ADP3310 is very easy to use. A P-channel power MOSFET
and a small capacitor on the output is all that is needed to form
an inexpensive ultralow dropout regulator. The advantage of
using the ADP3310 controller is that it can drive a pass PMOS
FET to provide a regulated output at high current.
FET Selection
The type and size of the pass transistor are determined by the
threshold voltage, input-output voltage differential and load
current. The selected PMOS must satisfy the physical and
thermal design requirements. Table I shows a partial list of
manufacturers providing the PMOS devices. To ensure that the
maximum V
GS
provided by the controller will turn on the FET
at worst case conditions (i.e., temperature and manufacturing
tolerances), the maximum available V
GS
must be determined.
Maximum V
GS
is calculated as follows:
(1) V
GS
= V
IN
– V
BE
– I
OMAX
×
R
S
I
OMAX
= Maximum Output Current
R
S
= Current Sense Resistor
V
BE
~ 0.7 V (Room Temp)
~ 0.5 V (Hot)
~ 0.9 V (Cold)
For Example: V
IN
= 5 V, V
O
= 3.3 V and I
OMAX
= 3 A,
V
GS
= 5 V – 0.7 V – 3 A
×
11 m
= 4.27 V
Equation (1) applies to a gate-to-source voltage less than the
gate to source clamp voltage.
(2) V
DS
= V
IN
– V
O
V
DS
= 5 V – 3.3 V = 1.7 V
If V
IN
≤
5 V, logic level FET should be considered.
If V
IN
> 5 V, either logic level or standard MOSFET can be used.
The difference between V
IS
and V
OUT
(V
DS
) must exceed the
voltage drop due to the load current and the ON resistance of
the FET. As a safety margin, it is recommended to use a MOS-
FET with a V
GS
at least 1.5 times lower than the calculated V
GS
value from Equation 1. Also, in the event the circuit is shorted
to ground, the MOSFET must be able to conduct the maximum
short circuit current. The selected MOSFET must satisfy these
criteria; otherwise, a different pass device should be used. If the
FET data is not available in the catalogue, contact the FET
manufacturer.
Thermal Design
The maximum allowable thermal resistance between the FET
junction and the highest ambient temperature must be taken
into account to determine the type of FET package used. One
square inch of PCB copper area as heatsink yields a typical
θ
JA
~ 60
°
C/W for the SOT-223 package and
θ
JA
~ 50
°
C/W for
the SO-8 package. For substantially lower thermal resistances,
D
2
PAK or TO-220 type of packages are recommended.
For normal applications, the FET can be directly mounted to the
PCB. But, for higher power applications, an external heat sink is
required to satisfy the
θ
JA
requirement and provide adequate heatsink.
Calculating thermal resistance for V
IN
= 5 V, V
O
= 3.3 V, and
I
O
= 3 A:
θ
J
A
=
T
J
–
T
AMBMAX
(
V
DSMAX
×
I
OMAX
)
T
J
T
AMBMAX
= Maximum Ambient Temperature
= Junction Temperature
V
DSMAX
I
OMAX
= Maximum Drain to Source Voltage
= Maximum Output Current
125
50
1.7
×
3
For such a low
θ
JA
, a P-channel FET from Fairchild, such as
NDP6020P in a heatsink mountable TO-220 package, is
required. The required external heatsink is determined as
follows:
θ
CA
=
θ
JA
–
θ
JC
θ
CA
= Case-to-Ambient Thermal Resistance
θ
JA
= Junction-to-Ambient Thermal Resistance
θ
JC
= Junction-to-Case Thermal Resistance
θ
JC
= 2
°
C/W for NDP6020P
θ
CA
= 14.7
°
C/W – 2
°
C/W = 12.7
°
C/W
For a safety margin, select a heatsink with a
θ
CA
less than half of
the value calculated above to allow extended duration of short
circuit. In a natural convection environment, a large heatsink
such as 3" length of Type 63020 extrusion from Aavid Engineering
is required.
External Capacitors
The ADP3310 is stable with virtually any good quality capaci-
tors (anyCAP), independent of the capacitor’s minimum ESR
(Effective Series Resistance) value. The actual value of the ca-
pacitor and its associated ESR depends on the g
m
and ca-
pacitance of the external PMOS device. A 10
μ
F capacitor at the
output is sufficient to ensure stability for up to 10A output
current. Larger capacitors can be used if high output current
surges are anticipated. Extremely low ESR capacitors (ESR
≈
0)
such as multilayer ceramic or OSCON are preferred because
they offer lower ripple on the output. For less demanding
requirements, a standard tantalum or even an aluminum
electrolytic is adequate. However, if an aluminum electrolytic is
used, be sure it meets the temperature requirements because
aluminum electrolytic has poor performance over temperature.
Shutdown Mode
Applying a TTL high signal to the EN pin or tying it to the
input pin will enable the output. Pulling this pin low or tying it
to ground will disable the output. In shutdown mode, the
controller’s quiescent current is reduced to less than 1
μ
A.
Gate-to-Source Clamp
An 8 V gate-to-source voltage clamp is provided to protect the
MOSFET in the event the output is suddenly shorted to
ground. This allows the use of the new, low on-state resistance
(R
DSON
) FETs.
Short Circuit Protection
The power FET is protected during short circuit conditions
with a foldback type of current limiting which significantly re-
duces the current.
Current Sense Resistor
Current limit is achieved by setting an appropriate current sense
resistor (R
S
) across the current limit threshold voltage. Current
limit sense resistor R
S
is calculated as follows:
θ
JA
=
=
14.7
°
C
/
W
R
S
=
0.05
(1.5
×
I
O
)
anyCAP is a trademark of Analog Devices, Inc.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ADP3310AR-33 | Circular Connector Cable Assembly; Connector Type A:Circular Receptacle; Connector Type B:Stripped End Leads; Cable Length:10ft RoHS Compliant: Yes |
| ADP3310AR-5 | Precision Voltage Regulator Controller |
| ADP3310AR-2.8 | THREE-TERMINAL POSITIVE FIXED VOLTAGE REGULATORS |
| ADP3310AR-3.3 | THREE-TERMINAL POSITIVE FIXED VOLTAGE REGULATORS |
| ADP3310 | Precision Regulator Controllers(精密穩(wěn)壓控制器) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADP3310AR-3.3 | 制造商:Rochester Electronics LLC 功能描述:LOW DROPOUT-REGULATOR CONTROLLER - Bulk |
| ADP3310AR-3.3-REEL | 制造商:Rochester Electronics LLC 功能描述:LOW DROPOUT-REGULATOR CONTROLLER - Tape and Reel |
| ADP3310AR-33 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision Voltage Regulator Controller |
| ADP3310AR-3-REEL | 制造商:Analog Devices 功能描述:DC DC Cntrlr Single-OUT 2.5V to 15V Input 8-Pin SOIC T/R |
| ADP3310AR-5 | 制造商:Rochester Electronics LLC 功能描述:LOW DROPOUT-REGULATOR CONTROLLER - Bulk 制造商:Analog Devices 功能描述: |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。