NCP3125 PDF даташит
Спецификация NCP3125 изготовлена «ON Semiconductor» и имеет функцию, называемую «4 A Synchronous PWM Switching Converter». |
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Детали детали
Номер произв | NCP3125 |
Описание | 4 A Synchronous PWM Switching Converter |
Производители | ON Semiconductor |
логотип |
22 Pages
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NCP3125
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4 A Synchronous PWM
Switching Converter
The NCP3125 is a flexible synchronous PWM Switching Buck
Regulator. The NCP3125 is capable of producing output voltages as
low as 0.8 V. The NCP3125 also incorporates voltage mode control.
To reduce the number of external components, a number of features
are internally set including switching frequency. The NCP3125 is
currently available in an SOIC−8 package.
Features
• 4.5 V to 13.2 V Operating Input Voltage Range
• 60 mW High−Side, 36 mW Low−Side Switches
• Output Voltage Adjustable to 0.8 V
• 4 A Continuous Output Current
• Fixed 350 kHz PWM Operation
• 1.0% Initial Output Accuracy
• 75% Max Duty Ratio
• Short−Circuit Protection
• Programmable Current Limit
• This is a Pb−Free Device
Typical Application
• Set Top Boxes
• DVD Drives and HDD
• LCD Monitors and TVs
• Cable Modems
• Telecom / Networking / Datacom Equipment
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8
1
SOIC−8 NB
D SUFFIX
CASE 751
MARKING
DIAGRAM
8
3125
ALYWXG
G
1
3125
A
L
Y
W
G
= Specific Device Code
= Assembly Location
= Wafer Lot
= Year/
= Work Week
= Pb−Free Package
PIN CONNECTIONS
PGND
FB
COMP
AGND
1
(Top View)
VSW
ISET
VIN
BST
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 21 of this data sheet.
4.5 V − 13.2 V
VIN
BST
VSW
PGND
NCP3125
ISET
FB1
COMP
AGND
Figure 1. Typical Application Circuit
3.3 V
100
95 5 V
90
85
80
75
70
65
0 0.5 1 1.5 2 2.5 3 3.5 4
OUTPUT CURRENT (A)
Figure 2. Efficiency (VIN = 12 V) vs. Load Current
© Semiconductor Components Industries, LLC, 2010
April, 2010 − Rev. 1
1
Publication Order Number:
NCP3125/D
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−
+
VREF
+
0.8 V
FB −
COMP
NCP3125
CIRCUIT DESCRIPTION
10 mA
Fault
UVLO
POR
Latch
SCP
+
−
+ VOCTH
−
+
PWM
Comp
−
R
PWM
OUT
Q
S
Fault
Clock
Ramp
OSC
OSC
Count
Latch
&
Logic
Counter
DtoA
+
−
VREG
+ 0.7 V
−
Fault
−
+
+
−
2V
BST
VCC
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VIN
VSW
AGND
Figure 3. NCP3125 Block Diagram
ISET
PGND
Table 1. PIN DESCRIPTION
Pin Pin Name
Description
1
PGND
The PGND pin is the high current ground pin for the low−side MOSFET and the drivers. The pin should be
soldered to a large copper area to reduce thermal resistance.
2 FB Inverting input to the Operational Transconductance Amplifier (OTA). The FB pin in conjunction with the
external compensation, serves to stabilize and achieve the desired output voltage with voltage mode
control.
3
COMP
COMP pin is used to compensate the OTA which stabilizes the operation of the converter stage. Place
compensation components as close to the converter as possible.
4
AGND
The AGND pin serves as small−signal ground. All small−signal ground paths should connect to the AGND
pin at a single point, avoiding any high current ground returns.
5 BST Supply rail for the floating top gate driver. To form a boost circuit, use an external diode to bring the desired
input voltage to this pin (cathode connected to BST pin). Connect a capacitor (CBST) between this pin and
the VSW pin. Typical values for CBST range from 1 nF to 10 nF. Ensure that CBST is placed near the IC.
6 VIN The VIN pin powers the internal control circuitry and is monitored by an undervoltage comparator. The VIN
pin is also connected to the internal power NMOSFET switches. The VIN pin has high dI/dt edges and must
be decoupled to PGND pin close to the pin of the device.
7
ISET
Current set pin and bottom gate MOSFET driver. Place a resistor to ground to set the current limit of the
converter.
8
VSW
The VSW pin is the connection of the drain and source of the internal N−MOSFETs. The VSW pin swings
from VIN when the high side switch is on to small negative voltages when the low side switch is on with high
dV/dt transitions.
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NCP3125
Table 2. MAXIMUM RATINGS
Rating
Symbol
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Min Max Unit
Main Supply Voltage Input
Bootstrap Supply Voltage vs GND
VIN
VBST
−0.3
−0.3
15 V
15 V
Bootstrap Supply Voltage vs Ground (spikes ≤ 50 ns)
Bootstrap Pin Voltage vs VSW
High Side Switch Max DC Current
VSW Pin Voltage
Switching Node Voltage Excursion (200 mA)
Switch Pin voltage (spikes < 50 ns)
FB Pin Voltage
COMP/DISABLE
Low Side Driver Pin Voltage
Low Side Driver Pin Voltage (spikes v 200 ns)
Rating
VBST spike
VBST−VSW
IVSW
VSW
VSWLIM
VSWtr
VFB
VCOMP/DIS
VISET
VISET Spike
Symbol
−5.0
−0.3
0
−0.3
−2.0
−5.0
−0.3
−0.3
−0.3
−2
35
15
4
30
35
40
5.5 < VCC
5.5 < VCC
15 < VCC
15 < VCC
Rating
V
V
A
V
V
V
V
V
V
V
Unit
Thermal Resistance, Junction−to−Ambient
(Note 2)
(Note 3)
RqJA
110 °C/W
183
Thermal Resistance, Junction−to−Case
Storage Temperature Range
RqJC
Tstg
170
−55 to 150
°C/W
°C
Junction Operating Temperature
Lead Temperature Soldering (10 sec):
Reflow (SMD styles only) Pb−Free
TJ
−40 to 125
°C
RF
260 peak
°C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. The maximum package power dissipation limit must not be exceeded.
2. The value of qJA is measured with the device mounted on 1 in2 FR−4 board with 1 oz. copper, in a still air environment with TA = 25°C. The
value in any given application depends on the user’s specific board design.
3. The value of qJA is measured with the device mounted on minimum footprint, in a still air environment with TA = 25°C. The value in any given
application depends on the user’s specific board design.
4. 60−180 seconds minimum above 237°C.
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