+12V, 30mA Flash Memory
Programming Supply
Table 1. Capacitor Suppliers
Supplier
Murata Erie
Phone Number
(814) 237-1431
Fax Number
(814) 238-0490
RPE123Z5U105M50V
Sprague Electric
(603) 224-1961
(207) 324-4140
(603) 224-1430
(207) 324-7223
595D475X9016A7
595D105X9016A7
1.0µF Ceramic (TH)
4.7µF Tantalum (SM)
1.0µF Tantalum (SM)
Capacitor
GRM42-6Z5U224M50
Capacitor Type*
0.22µF Ceramic (SM)
MAX662A
*Note: (SM) denotes surface-mount component, (TH) denotes through-hole component.
Layout Considerations
2
C1
0.22µF
3
C2
0.22µF
V
IN
4.75V TO 5.5V
V
OUT
+12V ±5%
AT 30mA
C4
4.7µF
C5
4.7µF
C2-
C1+
4
5
MAX662A
C2+
V
CC
C1-
SHDN
1
8
Layout is critical, due to the MAX662A’s high oscillator
frequency. Good layout ensures stability and helps
maintain the output voltage under heavy loads. For best
performance, use very short connections to the capaci-
tors. The order of importance is: C4, C5, C1, C2.
Flash EEPROM Applications
PROGRAMMING
CONTROL
DIRECT FROM
µP
6
V
OUT
GND
7
The circuit of Figure 3a is a +12V ±5% 30mA flash
EEPROM programming power supply. A microproces-
sor controls the programming voltage via the SHDN
pin. When SHDN is low, the output voltage (which is
connected to the flash memory V
PP
supply-voltage pin)
rises to +12V to facilitate programming the flash memo-
ry. When SHDN is high, the output voltage is connected
to V
IN
through an internal 1kΩ resistor.
Figure 3a. Flash EEPROM Programming Power Supply for
Commercial Temperature Range Applications
Paralleling Devices
Two MAX662As can be placed in parallel to increase
output drive capability. The V
CC
, V
OUT
, and GND pins
can be paralleled, reducing pin count. Use a single
bypass capacitor and a single output filter capacitor
with twice the capacitance value if the two devices can
be placed close to each other. If the MAX662As cannot
be placed close together, use separate bypass and
output capacitors. The amount of output ripple
observed will determine whether single input bypass
and output filter capacitors can be used. Under certain
conditions, one device may supply the total output cur-
rent. Therefore, regardless of the number of devices in
parallel, the maximum continuous current must not
exceed 50mA.
3
*C2
1.0µF
V
IN
4.75V TO 5.5V
*C4
22µF
V
OUT
+12V ±5%
AT 30mA
*C5
22µF
C2-
C1+
2
*C1
1.0µF
4 C2+
5
V
CC
MAX662A
C1-
SHDN
1
8
6
V
OUT
GND
7
PROGRAMMING
CONTROL
DIRECT FROM
µP
12V and 20V Dual-Output Power Supply
*SPRAGUE 595D SERIES OR EQUIVALENT
Figure 3b. Flash EEPROM Programming Power Supply for
Extended and/or Military Temperature Range Applications
Using the charge-pump voltage-doubler circuit of
Figure 4, the MAX662A can produce a +20V supply
from a single +5V supply. Figure 5 shows the current
capability of the +20V supply.
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5
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
