SINK AND SOURCE DC/DC CONTROLLER FOR
TERMINATION POWER SUPPLY APPLICATIONS
PRELIMINARY - October 9, 2000
SC1110
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
The SC1110 is a low-cost, full featured, synchronous
voltage-mode controller designed to generate termina-
tion voltage in double data rate (DDR) memory sys-
tems and other applications where wide data bus need
to be actively terminated. Synchronous control of the
MOSFET half bridge allows power flowing bi-
directionally. The termination voltage can be tightly
regulated to track the chipset voltage, i.e. to be exactly
50% of that at all times.
The SC1110 is ideal for low cost implementation of ter-
mination voltage supplies. SC1110 features include
temperature compensated voltage reference, triangle
wave oscillator and current sense comparator circuitry,
and allows the use of inexpensive N-channel power
switches.
The SC1110 operates at a fixed 250kHz, providing an
optimum compromise between efficiency, transient
performance, external component size, and cost.
FEATURES
鈥?
Generates termination voltages for active termina-
鈥?
鈥?
鈥?
鈥?
鈥?
鈥?
鈥?
鈥?
tion schemes
1% set point accuracy
For 鹵7A output current, transient regulation is bet-
ter than 鹵80mV
V
REFIN
pin available
Buffered V
REFOUT
for system usage
R
DSON
sensing for over current protection in hiccup
mode
Soft start and logic input enabling
250kHz switching for best transient and efficiency
performance
Gate drive capable for 0.5A sourcing and sinking
APPLICATIONS
鈥?
For DDR memory systems
鈥?
For active termination schemes in high speed logic
systems
ORDERING INFORMATION
DEVICE
(1)
PACKAGE
SO-14
TEMP. RANGE (T
J
)
0 - 125擄C
SC1110CSTR
Note:
TYPICAL APPLICATION CIRCUIT
REFOUT
(1) Only available in tape and reel packaging. A reel
contains 2500 devices.
+5Vcc
+
R1
5k
C1
0.01
R2
1.24k
C2
0.1
R3
10
U1
SC1110
VCC
REFOUT
14
R4
1k
C4
0.022
C7
1.0
C8,9
2 x 10uF
C10,11
2 x 560uF
Vin 2.5V
_
1
SS/ENBL
2
C3
0.1
PWRGD
4
C25
0.1
5
SS/ENBL
REFIN
13
R5
1k
3
OCSET
SENSE
12
R6
4.7k
C5
0.047
PWRGD
COMP
11
GND
BSTL
10
D1
MBRM120
6
PHASE
BSTH
9
R7
2.2
R8
2.2
Q1
Si9426DY
Q2
Si9426DY
C12-14
3 x 560uF
C15-24
10 x 10uF
C6
1.0
L1
800 nH
7
DL
DH
8
+
Vout = 1.25V @ 7A
_
C10-14: Sanyo, 4SP560M
C8,9,15-24: TDK, CC3216AX5R0J106K
L1: Panasonic, ETQP6F0R8L or Falco, QPIP1205-809-3
Q1,Q2 options: Si9426DY, FDS6890A, IRF7401
D1: ON Semi (Motorola)
1
漏 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
SEMTECH
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