SC4901 PDF даташит
Спецификация SC4901 изготовлена «Semtech Corporation» и имеет функцию, называемую «COMBI-SYNC Secondary Side Synchronous Rectifier and Regulator». |
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Детали детали
Номер произв | SC4901 |
Описание | COMBI-SYNC Secondary Side Synchronous Rectifier and Regulator |
Производители | Semtech Corporation |
логотип |
20 Pages
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POWER MANAGEMENT
SC4901
COMBI-SYNC Secondary Side
Synchronous Rectifier and Regulator
Description
Features
SC4901 is a unique secondary side regulator designed
for implementing Semtech’s proprietary Combi-Sync
topology for isolated convertors with multiple outputs. The
Combi-Sync is a true all-MOSFET topology that allows
synchronous rectification and post regulation of
transformer isolated outputs, resulting in higher efficiency
and low component count. Details of this unique topology
are described in the Application Information section.
www.DataMShueeltt4ipUl.ecomoutputs can be synchronously rectified and
independently regulated by individual SC4901s. Each
output has its own ON/OFF control, soft start, remote sense
and current limits. They can be turned on or off without
affecting the primary or other outputs. The secondary side
control makes it much easier to design tight control loops
and implement load current sharing and hot swap
features. All devices are synchronised to the transformer
winding. The current sense can be either from the output
inductor for high efficiency or a resistor for better accuracy.
An amplified current signal is provided for external use.
Single controller performs synchronous rectification
and post regulation
Independent regulation of multiple outputs from a
common secondary winding
Turn on shoot through inherently eliminated
Primary switch turns ON and OFF with zero current
No synchronising or any other signals needed across
the isolation boundary
Eliminates the need for a secondary bias supply
Independent soft start, ON/OFF, remote sense and
current limit for each output
Resistive or inductive current sensing with 2V current
signal and 2.5V reference for external applications.
4.5 to 18V operation
Max operating frequency to 1 MHz
Low profile 16 pin TSSOP package
Based on Semtech’s patented Combi Sync
concept
Applications
Each device is capable of driving high side MOSFETs with
2A current. The forward drive is configured for direct
connection to a 1:1 pulse transformer. SC4901 has an
undervoltage lockout with typical turn-on threshold of 4.5V
and is available in a low cost TSSOP-16 package
Typical Application Circuit
Telecom isolated DC to DC converters with multiple
low voltage outputs
High density brick and sub brick modules with
independently regulated multiple outputs
Distributed power architectures
Isolated VRMs
SIN GLE
EN DED
FORWARD
C ON VER TOR
••
T1
QS
T2
R4 R5
QF
R8
L1
QR
R9
R1
R6 R7
VO UT
R2 R3
C1 C2
R10
C3
R TN
D1 D2
RZ RT R13 D3
C6
R14
C4 C5
U 1 S C 4901
R11 R12
CAO
D4
CT
Revision: May, 2005
C9 C8 C7
C10 R15
United States Patent 6,788,554
1
www.semtech.com
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SC4901
POWER MANAGEMENT
Absolute Maximum Ratings
Exceeding the specifications below may result in permanent damage to the device, or device malfunction.
Operation outside of the parameters specified in the Electrical Characteristics section is not implied.
Parameter
Symbol
Maximum
Supply Voltage
Ground voltages
Output Voltages
CS+ and CS- common mode voltage
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ZCD pin wrt to AGND
All other pins wrt AGND
Max current into ZCD pin
Max current into RCT pin
OUTA, XFRA Current Source or Sink
OUTB Current Source or Sink
Ambient Temperature Range
Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering) 10 Sec.
ESD Rating (Human Body Model)
Electrical Characteristics
Unless specified: TA = 25°C, VCC = 12V
AVCC, PVCC
AGND to PGND
OUTA, XFRA, OUTB
CS+, CS-
VZCD
IZCD
IRCT
IOUTB
TA
TJ
TSTG
TLEAD
VESD
18
+0.3V
PVCC
VCC - 2
0 to 6V
-0.3 to +6
5 mA
2 mA
+2.0
+1.0
-40 to +125
-40 to +125
-60 to +150
260
2.0
Parameter
Power Supply
Operating Current
Undervoltage Lockout
Start Threshold
UVLO Hysteresis
Soft Start and Enable
Enable Threshold
SS Charge Current
SS Effective Discharge Current
Test Conditions
Min Typ
SSEN = 5V, VCC = 15V IOUTX = 0
7
AVCC rising
AVCC falling
4.3 4.5
0.3
VENA
ISS
-ISS
0.55 0.65
8 10
1.5
Units
V
V
V
V
V
V
mA
mA
A
A
°C
°C
°C
°C
kV
Max Unit
10 mA
4.8 V
V
0.75 V
12 µA
µA
2005 Semtech Corp.
2
www.semtech.com
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POWER MANAGEMENT
Electrical Characteristics (Cont.)
Unless specified: TA = 25°C, VCC = 12V
Parameter
VREF Reference
Output Voltage
Output Current
Line Regulation
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Load Regulation
Error Amplifier
Reference Voltage Level
Input Bias Current
Offset Voltage (1)
Open Loop Gain (1)
Unity Gain Bandwidth (1)
Slew Rate (1)
Output High Voltage
Output Low Voltage
ZCD and RCT
Frequency Range
Peak Voltage (1)
Valley Voltage (1)
Timing Capacitor Discharge Current (1)
Current Limit
Cycle by Cycle Threshold
Hiccup Mode Threshold
Delay to Output (1)
Current Amplifier offset
Test Conditions
TA = TJ = -40 °C to +125°C
IREF
8V < AVCC < 15V
0 mA < IREF < 5 mA
TA = 25 °C
TA = TJ = -40 °C to +125°C
ICOMP = 0.1 mA source
ICOMP = 0.1 mA sink
Frequency range Min
Frequency range Max
Clamped internally
VCAO
VEA- falling
SC4901
Min Typ Max Unit
2.4 2.5 2.6 V
5 mA
10 mV
10 mV
0.74
0.735
2.7
0.750
0.1
2
80
3
2.0
2.9
0.76
0.765
2
0.8
V
V
µA
mV
dB
MHz
V/µS
V
V
50
1000
3.0
1.0
11
KHz
V
V
mA
2.3 2.5 2.7 V
0.375
V
75 nS
2 5 mV
2005 Semtech Corp.
3
www.semtech.com
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