SC4810B_16 Datasheet, PDF (1/24 Pages) Semtech Corporation – High Performance Current Mode PWM Controller with Complementary Output, Programmable Delay

SC4810B/E
High Performance Current Mode PWM Controller
with Complementary Output, Programmable Delay
POWER MANAGEMENT
Description
Features
The SC4810B/E is a 16 pin BICMOS primary side PWM
controller for use in Isolated DC-DC and off-line switching
power supplies. It is a highly integrated solution, requiring
few external components. It features a high frequency
of operation, accurately programmable maximum duty
cycle, current mode control, line voltage monitoring, supply
UVLO, low start-up current, and programmable soft start
with user accessible reference. It operates in a fixed
frequency, highly desirable for Telecom applications. The
output for switch is complementary to each other with
programmable delay between each transition. The active
technique allows single ended converters beyond 50%
duty cycle and greater flux swing for the power
transformer while reducing voltage stresses on the
switches. The separate sync pin simplifies synchronization
to an external clock. Feeding the oscillator of one device
to the sync of another forces biphase operation which
reduces input ripple and filter size.
The SC4810B/E has a turn-on voltage threshold of 7V.
In the SC4810B, OUT2 is inverted to drive the N-MOSFET.
In the SC4810E, OUT2 is non-inverted to drive the
P-MOSFET. These devices are available in a TSSOP-16 or
MLPQ-16 lead package.
‹ Operation to 1MHz
‹ Accurate programmable maximum duty cycle
‹ Line voltage monitoring
‹ External frequency synchronization
‹ Bi-phase mode of operation for low ripple
‹ Independent programmable delays
‹ Hiccup mode current limit
‹ Under 250µA start-up current
‹ Programmable maximum volt-second clamp
‹ Accessible reference voltage
‹ VDD undervoltage lockout
‹ -40°C to 105°C operating temperature
‹ 16 lead TSSOP or MLPQ lead free packages. Both
fully WEEE and RoHS compliant
Applications
‹ Telecom equipment and power supplies
‹ Networking power supplies
‹ Power over LAN applications
‹ Industrial power supplies
‹ Isolated power supplies
‹ VoIP phones
Typical Application Circuit
+48V
R1
D1
C1
D2
Q1
C3
R2
C4
C5
T1
D3
D4
R3
R5
C9
R6
C8
U2
U1
S C 130 2A
C7
T2
R7
2
7
C6
R4
Q2
D5
C10
6 _RAMP
OUT2 ¹³ ₄
5
R9
3 _SYNC
OUT1 ¹⁵
R10
4 _{RCT SC4810}
CS ¹⁰
R 11
5 _DMAX
FB ¹¹
C 11
R12
7 _{DELAY 1}
VREF ¹⁶
C13
Q4
R17
R 14
8 _{DELAY 2}
R18 _R19
SS
9 C12
C 15
Q3
U3
R 13
1
6
5
2
R 20
R22
R23
C 16
L1
C2
R8
R15
C14
U4
SC 431L
Vout
R16
R21
Revision: July 27, 2006
1
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