參數(shù)資料
型號(hào): SC486IMLTRT
廠商: Semtech Corporation
英文描述: Complete DDR1/2/3 Memory Power Supply
中文描述: 完全DDR1/2/3內(nèi)存供電
文件頁(yè)數(shù): 1/26頁(yè)
文件大?。?/td> 382K
代理商: SC486IMLTRT
1
www.semtech.com
SC486
Complete DDR1/2/3
Memory Power Supply
POWER MANAGEMENT
Description
Revision: September 13, 2006
The SC486 is a combination switching regulator and linear
source/sink regulator intended for DDR1/2/3 memory
systems. The switching regulator is used to generate the
supply voltage, VDDQ, for the memory system. It is a
pseudo-fixed frequency constant on-time controller
designed for high efficiency, superior DC accuracy, and
fast transient response. The linear source/sink regulator
is used to generate the memory termination voltage, VTT,
with the ability to source and sink a 3A peak current.
For the VDDQ regulator, the switching frequency is
constant until a step in load or line voltage occurs at
which time the pulse density, i.e. frequency, will increase
or decrease to counter the transient change in output or
input voltage. After the transient, the frequency will return
to steady-state operation. At lighter loads, the selectable
Power-Save Mode enables the PWM converter to reduce
its switching frequency and improve efficiency. The
integrated gate drivers feature adaptive shoot-through
protection and soft-switching.
For the VTT regulator, the output voltage tracks VREF,
which is VDDQ to provide an accurate termination
voltage. The VTT output is generated from a 1.2V to VDDQ
input by a linear source/sink regulator which is designed
for high DC accuracy, fast transient response, and low
external component count. Additional features include
cycle-by-cycle current limiting, digital soft-start, power
good (all VDDQ only) and over-voltage and under-voltage
protection (VDDQ and VTT). All 3 outputs (VDDQ, VTT and
REF) are actively discharged when VDDQ is
disabled,
reducing external component count and cost. The SC486
is available in a 24 pin MLPQ 4mmx4mm Lead-free
package.
Typical Application Circuit
Notebook computers
CPU I/O supplies
Handheld terminals and PDAs
LCD monitors
Network power supplies
DDR1, DDR2 and DDR3 compatible
Constant on-time controller for fast dynamic
response on VDDQ
Programmable VDDQ range - 1.5V to 3V
1% Internal Reference (2% System Accuracy)
Resistor programmable on time for VDDQ
VCCA/VDDP range = 4.5V to 5.5V
VBAT range = 2.5V to 25V
VDDQ DC current sense using low-side R
sensing or external R
SENSE
in series with low-side
FET
Cycle-by-cycle current limit for VDDQ
Digital soft-start for VDDQ
Combined EN and PSAVE pin for VDDQ
Over-voltage/under-voltage fault protection for
both outputs and PGD output (VDDQ only)
Separate VCCA and VDDP supplies
VTT/REF range = 0.75V – 1.5V
VTT source/sink 3A peak
Internal resistor divider for VTT/REF
VTT is high impedance in S3
VDDQ, VTT and REF are actively discharged in
S4/S5
24-pin MLPQ (4 x 4mm) Lead-free package, fully
WEEE and RoHS compliant
Applications
+
C10
VDDQ
C12
1uF
C11
20uF
VTT
C9
1uF
R2
10R
5VRUN
5VSUS
C3
no-pop
R7 10R
REF
R6
10R
C6
1uF
R4 10R
C2
1uF
R5
R9
VDDQ
PGOOD
VBAT
C8
1nF
C1
no-pop
C7
no-pop
R8 0R
VDDQ
4
1
2
3
5
6
7
8
Q1
R10
C13
1uF
C4
0.1uF
D1
R3 470k
5VSUS
C5
10uF
R1
VBAT
L1
PGND1
18
REF
8
EN/PSV
1
TON
2
VDDQS
3
VCCA
5
FB
6
PGD
7
VSSA
4
PGND2
17
DL
19
VDDP
20
ILIM
21
LX
22
DH
23
BST
24
VTTEN
11
VTT
15
PGND2
16
VTTIN
VTTIN
12
13
VTT
14
VTTS
10
COMP
9
P
U1
SC486
Features
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