MAX864 Maxim, MAX864 Datasheet - Page 9

• Manufacturer Part Number: MAX864
• Description: Dual-Output Charge Pump with Shutdown
• Manufacturer: Maxim

When under heavy loads, where V+ is sourcing current
into V- (i.e., load current flows from V+ to V-, rather than
from supply to ground), do not allow the V- supply to
pull above ground. In applications where large currents
flow from V+ to V-, use a Schottky diode (1N5817)
between GND and V-, with the anode connected to
GND (Figure 5).
Good layout is important, primarily for good noise per-
formance. To ensure good layout, mount all compo-
nents as close together as possible, keep traces short
to minimize parasitic inductance and capacitance, and
use a ground plane. Connecting all N.C. pins to a
ground plane improves thermal dissipation.
Figure 4. Paralleling Two MAX864s
V
IN
3.3 F
3.3 F
Dual-Output Charge Pump with Shutdown
_______________________________________________________________________________________
1
2
3
4
Heavy Output Current Loads
C1-
C2+
C2-
V-
MAX864
Layout and Grounding
GND
C1+
V+
IN
8
7
6
5
3.3 F
3.3 F
Figure 5. High V- Load Circuit
1
2
3
4
C1-
C2+
C2-
V-
MAX864
GND
C1+
V+
IN
MAX864
8
7
6
5
GND
V-
11
5
3.3 F
3.3 F
GND
V
V+ OUT
V- OUT
IN
9