sc480imltrt Semtech Corporation, sc480imltrt Datasheet - Page 8

• Manufacturer Part Number: sc480imltrt
• Description: Sc480 Complete Ddr1/2/3 Memory Power Supply
• Manufacturer: Semtech Corporation

Notes:
1) EN/PSV = 1 = EN/PSV high or fl oating.
2) Typical discharge resistances: VTT = 0.25Ω. REF = 8Ω.
3) VDDQ is discharged via external series resistance which must be added to SC480 internal discharge resistance to calculate discharge times.
This is separate from any external load on VDDQ.
The FB pin can be confi gured for fi xed or adjustable output voltage as shown.
© 2006 Semtech Corp.
POWER MANAGEMENT
POWER MANAGEMENT
Enable Control Logic
FB Confi guration Table
Pin Description (Cont.)
17,18
FB Resistors
16
19
20
21
22
23
24
EN/PSV
T
VCCA
GND
FB
Enable Pin Status
0
0
1
1
THERMAL
(1)
PGND1
VTTIN
PAD
ILIM
BST
VTT
DH
DL
LX
Adjustable
VDDQ(V)
VTTEN
Current limit input pin. Connect to drain of low-side MOSFET for RDS(on) sensing or the source
for resistor sensing through a threshold sensing resistor.
Power ground for VDDQ switching circuits. Connect to thermal pad and ground plane.
Gate drive output for the low side MOSFET switch.
Phase node - the junction between the top and bottom FETs and the output inductor.
Gate drive output for the high side MOSFET switch.
Boost capacitor connection for the high side gate drive.
Input supply for the high side switch for VTT regulator. Decouple with a 1μF capacitor to
PGND2.
Output of the linear regulator. Decouple with two (minimum) 10μF ceramic capacitors to
PGND2, locating them directly across pins 24 and 1.
2.5
1.8
Pad for heatsinking purposes. Connect to ground plane using multiple vias. Not connected
internally.
0
1
0
1
OFF, Discharged
OFF, Discharged
VREF & VTT (V)
VDDQS/2
VDDQS/2
VDDQS/2
VDDQ
ON
ON
(3)
(2)(3)
(2)(3)
8
OFF, High Impedance
1.5V < VDDQ < 3.0V
OFF, Discharged
OFF, Discharged
Output Status
VTT
ON
DDR1
DDR2
Note
(2)
(2)
(2)
OFF, Discharged
OFF, Discharged
REF
www.semtech.com
ON
ON
SC480
(2)
(2)
(2)