SC488ML View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
SC488ML Datasheet PDF : 24 Pages
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SC488
POWER MANAGEMENT
Pin Description (Cont.)
14,15
VDDP +5V supply voltage input for the VDDQ gate drivers.
16
ILIM
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.
17,18 PGND1 Power ground for VDDQ switching circuits. Connect to thermal pad and ground plane.
19
DL
Gate drive output for the low side MOSFET switch.
20
LX
Phase node - the junction between the top and bottom FETs and the output inductor.
21
DH
Gate drive output for the high side MOSFET switch.
22
BST
Boost capacitor connection for the high side gate drive.
23
VTTIN
Input supply for the high side switch for VTT regulator. Decouple with a 1μF capacitor to
PGND2.
24
VTT
Output of the linear regulator. Decouple with two (minimum) 10μF ceramic capacitors to
PGND2, locating them directly across pins 24 and 1.
T THERMAL Pad for heatsinking purposes. Connect to ground plane using multiple vias. Not connected
PAD
internally.
Enable Control Logic
Enable Pin Status
Output Status
EN/PSV (1)
VTTEN
VDDQ(3)
VTT(2)
REF(2)
0
0
OFF, Discharged
(2)(3)
OFF, Discharged
(2)
OFF, Discharged
(2)
0
1
OFF, Discharged
(2)(3)
OFF, Discharged
(2)
OFF, Discharged
(2)
1
0
ON
OFF, High Impedance
ON
1
1
ON
ON
ON
Notes:
1) EN/PSV = 1 = EN/PSV high or floating.
2) Typical discharge resistances: VTT = 0.32Ω. REF = 8Ω.
3) VDDQ is discharged via external series resistance which must be added to SC488 internal discharge resistance to calculate discharge times.
This is separate from any external load on VDDQ.
FB Configuration Table
The FB pin can be configured for fixed or adjustable output voltage as shown.
FB
VDDQ(V)
VREF & VTT (V)
GND
2.5
VDDQS/2
VCCA
1.8
VDDQS/2
FB Resistors
Adjustable
VDDQS/2
Note
DDR1
DDR2
1.5V < VDDQ < 3.0V
© 2006 Semtech Corp.
7
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