SC483 Datasheet PDF - Semtech Corporation
| Part Number | SC483 | |
| Description | Dual Synchronous Buck Pseudo Fixed Frequency Power Supply Controller | |
| Manufacturers | Semtech Corporation | |
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POWER MANAGEMENT
Description
SC483
Dual Synchronous Buck Pseudo Fixed
Frequency Power Supply Controller
Features
The SC483 is a dual output constant-on synchronous
buck PWM controller intended for use in notebook
computers and other battery operated portable devices.
Features include high efficiency and a fast dynamic
response with no minimum on time. The excellent
transient response means that SC483 based solutions
will require less output capacitance than competing fixed
frequency converters.
www.DataTShheeets4wU.ictocmhing frequency is constant until a step in load
or line voltage occurs at which time the pulse density
and frequency will increase or decrease to counter the
change in output or input voltage. After the transient
event, the controller frequency will return to steady state
operation. At light loads, Power-Save Mode enables the
SC483 to skip PWM pulses for better efficiency.
Each output voltage can be independently adjusted from
0.5V to VCCA. Two frequency setting resistors set the
on-time for each buck controller. The frequency can thus
be tailored to minimize crosstalk. The integrated gate
drivers feature adaptive shoot-through protection and
soft switching. Additional features include cycle-by-cycle
current limit, digital soft-start, over-voltage and under-
voltage protection, and a PGOOD output for each
controller.
Constant on-time for fast dynamic response
Programmable VOUT range = 0.5 – VCCA
VBAT Range = 1.8V – 25V
DC current sense using low-side RDS(ON)
sensing or sense resistor
Resistor programmable frequency
Cycle-by-cycle current limit
Digital soft-start
Separate PSAVE option for each switcher
Over-voltage/Under-voltage fault protection
10µA Typical shutdown current
Low quiescent power dissipation
Two Power Good indicators
1% Reference (2% system DC accuracy)
Integrated gate drivers with soft switching
Separate enables
28 Lead TSSOP
Industrial temperature range
Output soft discharge upon shutdown
Applications
Notebook computers
CPT I/O supplies
Handheld terminals and PDAs
LCD monitors
Network power supplies
VBAT
5VSU S
5VSU S
PGOOD
R1
R TON 1
R5
C5
1nF
R2
10R
VOU T1
R3
R7
C6
1uF
U1
22 EN/PSV1
23 TON1
24 VOUT1
25 VCCA1
26 FB1
27 PGD1
28 VSSA1
SC 483
BST1 7
DH1 6
LX1 5
ILIM1 4
VDDP1 3
DL1 2
PGND1 1
D1
C1 0.1uF
R4
C4
1uF
PGOOD
VBAT
VSSA1
5VSU S
R8
R TON 2
R9
10R
8 EN/PSV2
9 TON2
VOU T2
R 10
R 12
10 VOUT2
11 VCCA2
12 FB2
13 PGD2
C 11
1nF
R 14
C 12
1uF
14 VSSA2
5VSU S
BST2 21
DH2 20
LX2 19
ILIM2 18
VDDP2 17
DL2 16
PGND2 15
D2
C7 0.1uF
R 11
C 10
1uF
VSSA2
Revision: March 14, 2005
1
VBAT
Q1 C2
10uF
L1
VOU T1
C3
+
Q2 R6 0R
VSSA1
VBAT
Q3 C8
10uF
L2
VOU T2
C9
+
Q4 R13 0R
VSSA2
www.semtech.com
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POWER MANAGEMENT
Pin Configuration
www.DataSheet4U.com
SC483
Ordering Information
Device
SC483ITSTRT(2)
Package(1)
TSSOP-28
Notes:
(1) Only available in tape and reel packaging. A reel
contains 2500 devices.
(2) Lead free product. This product is fully WEEE, RoHS
and J-STD-020B compliant.
TSSOP-28
Pin Descriptions
Pin # Pin Name Pin Function
1 PGND1 Power ground.
2 DL1 Gate drive output for the low side MOSFET switch.
3 VDDP1 +5V supply voltage input for the gate drivers. Decouple this pin with a 1uF ceramic capacitor to
PGND1.
4 ILIM1 Current limit input. Connect to drain of low-side MOSFET for RDS(on) sensing or the source for
resistor sensing through a threshold sensing resistor.
5 LX1 Phase node (junction of top and bottom MOSFETs and the output inductor) connection.
6 DH1 Gate drive output for the high side MOSFET switch.
7 BST1 Boost capacitor connection for the high side gate drive.
8 EN/PSV2 Enable/Power Save input. Pull down to VSSA2 to shut down OUT2 and discharge it through
22Ω (nom). Pull up to enable OUT2 and activate PSAVE mode. Float to enable OUT2 and activate
continuous conduction mode (CCM), which should be used for dynamic voltage transitioning. If
floated, bypass to VSSA2 with a 10nF ceramic capacitor.
9 TON2 This pin is used to sense VBAT through a pullup resistor, RTON2, and to set the top MOSFET on-
time. Bypass this pin with a 1nF ceramic capacitor to VSSA2.
10 VOUT2 Output voltage sense input for output 2. Connect to the output at the load.
11 VCCA2 Supply voltage input for the analog supply. Use a 10 Ohm / 1uF RC filter from 5VSUS to VSSA2.
12 FB2 Feedback input. Connect to a resistor divider located at the IC from VOUT2 to VSSA2 to set the
output voltage from 0.5V to VCCA2.
13 PGD2 Power Good open drain NMOS output. Goes high after a fixed clock cycle delay (440 cycles)
following power up.
14 VSSA2 Ground reference for analog circuitry. Connect to PGND2 at the bottom of the output capacitor.
2005 Semtech Corp.
5
www.semtech.com
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for SC483 electronic component. |
| Information | Total 27 Pages | |
| Link URL | [ Copy URL to Clipboard ] | |
| Download | [ SC483.PDF Datasheet ] | |
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