MAX1661 Datasheet, PDF (14/16 Pages) Maxim Integrated Products – Active-Matrix Liquid Crystal Display AMLCD Supply

Active-Matrix Liquid Crystal Display
(AMLCD) Supply
Supply Connections and Layout
The MAX1664 performs both precision analog and
high-power switching functions. Carefully plan supply
connections, bypassing, and layout. Bypass IN and INP
with a 33Ω isolation resistor (R9, Figure 4) between
them. In addition, sufficient low-ESR bypassing must be
provided on the INP bus to ensure stability of DC-DC 1.
A solid ground plane under the power components,
with a separate ground plane under the analog nodes,
is highly recommended. These ground planes should
be connected at a single, quiet point. Analog reference
and feedback signals should be referred to and routed
over the analog ground plane. Figure 7 shows a typical
layout using separate ground planes.
REF
R5
V_OUT2-
-20V
C_OUT
4.7µF
R6
C_F
D4 ^D5
V1
0.47µF
D2
V_OUT2+
28V
0.22µF
D3
R7
R8
FB2-
MAX1664
LX2P
L2
LX2N
FB2+
PGND2
Figure 6. V_OUT2- Voltage-Doubler Charge Pump
1.0"
Figure 7a. MAX1664 Component Placement Guide
1.0"
Figure 7b. MAX1664 PC Board Layout—Component Side
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