19-0253; Rev 1; 8/94
NUAL
KIT MA
UATION TA SHEET
EVAL
WS DA
FOLLO
+12V, 30mA Flash Memory
Programming Supply
____________________________Features
o
Regulated +12V ±5% Output Voltage
o
4.5V to 5.5V Supply Voltage Range
o
Fits in 0.1in
2
o
Guaranteed 30mA Output
o
No Inductor—Uses Only 4 Capacitors
o
185µA Quiescent Current
o
Logic-Controlled 0.5µA Shutdown
o
8-Pin Narrow SO and DIP Packages
_______________General Description
The MAX662A is a regulated +12V, 30mA-output, charge-
pump DC-DC converter. It provides the necessary +12V
±5% output to program byte-wide flash memories, and
requires no inductors to deliver a guaranteed 30mA out-
put from inputs as low as 4.75V. It fits into less than 0.1in
2
of board space. The MAX662A is a pin-compatible
upgrade to the MAX662, and is recommended for new
designs. The MAX662A offers lower quiescent and shut-
down currents, and guarantees the output current over all
temperature ranges.
The MAX662A is the first charge-pump boost converter to
provide a regulated +12V output. It requires only a few
inexpensive capacitors, and the entire circuit is complete-
ly surface-mountable.
A logic-controlled shutdown pin that interfaces directly
with microprocessors reduces the supply current to only
0.5µA. The MAX662A comes in 8-pin narrow SO and DIP
packages.
For higher-current flash memory programming solutions,
refer to the data sheets for the MAX734 (120mA output
current, guaranteed) and MAX732 (200mA output cur-
rent, guaranteed) PWM, switch-mode DC-DC converters.
Or, refer to the MAX761 data sheet for a 150mA, PFM
switch-mode DC-DC converter that operates from inputs
as low as 2V.
MAX662A
______________Ordering Information
PART
MAX662ACPA
MAX662ACSA
MAX662AC/D
MAX662AEPA
MAX662AESA
MAX662AMJA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
________________________Applications
+12V Flash Memory Programming Supplies
Compact +12V Op-Amp Supplies
Switching MOSFETs in Low-Voltage Systems
Dual-Output +12V and +20V Supplies
* Dice are tested at T
A
= +25°C.
** Contact factory for availability and processing to MIL-STD-883.
__________Typical Operating Circuit
INPUT
4.75V TO 5.5V
__________________Pin Configuration
TOP VIEW
4.7µF
V
CC
SHDN
V
OUT
OUTPUT
12V ±5%
30mA
V
pp
C1- 1
C1+ 2
C2- 3
C2+ 4
8
7
SHDN
GND
V
OUT
V
CC
MAX662A
0.22µF
C1+
C2-
0.22µF
4.7µF
FLASH
MEMORY
MAX662A
6
5
C1-
GND
C2+
DIP/SO
________________________________________________________________
Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
+12V, 30mA Flash Memory
Programming Supply
MAX662A
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ................................................................-0.3V to 6V
SHDN..........................................................-0.3V to (V
CC
+ 0.3V)
I
OUT
Continuous..................................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW
SO (derate 5.88mW/°C above +70°C) .........................471mW
CERDIP (derate 8.00mW/°C above +70°C) .................640mW
Operating Temperature Ranges
MAX662AC_A .....................................................0°C to +70°C
MAX662AE_A ..................................................-40°C to +85°C
MAX662AMJA................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 3a, V
CC
= 4.5V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
0mA
≤
I
OUT
≤
30mA,
V
CC
= 4.75V to 5.5V
0mA
≤
I
OUT
≤
20mA
Output Voltage
V
OUT
MAX662AM
Supply Current
Shutdown Current
Oscillator Frequency
Power Efficiency
V
CC
-to-V
OUT
Switch Impedance
Shutdown Input Threshold
SHDN Pin Current
I
CC
f
OSC
R
SW
V
IH
V
IL
V
CC
= 5V, V
SHDN
= 0V
V
CC
= V
SHDN
= 5V
0mA
≤
I
OUT
≤
24mA,
V
CC
= 4.75V to 5.5V
0mA
≤
I
OUT
≤
16mA
No load, V
SHDN
= 0V
No load, V
SHDN
= V
CC
V
CC
= 5V, I
OUT
= 30mA
V
CC
= 5V, I
OUT
= 30mA
MAX662AC/E
V
CC
= V
SHDN
= 5V,
I
OUT
= 30mA
MAX662AM
2.4
-50
-15
0
0.4
-5
MIN
11.4
11.4
11.4
11.4
TYP
12
12
12
12
185
0.5
500
76
1
1
MAX
12.6
12.6
V
12.6
12.6
500
10
µA
µA
kHz
%
kΩ
V
µA
UNITS
MAX662AC/E
2
2.5
__________________________________________Typical Operating Characteristics
(Circuit of Figure 3a, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX662A-01
OUTPUT VOLTAGE vs. OUTPUT CURRENT
MAX662A-02
EFFICIENCY vs. LOAD CURRENT
90
V
CC
= 5.5V
80
EFFICIENCY (%)
70
60
50
40
30
V
CC
= 4.5V
V
CC
= 4.75V
V
CC
= 5.0V
CONTINUOUS OUTPUT CURRENT
MUST NOT EXCEED 50mA ABS MAX
LIMIT. INTERMITTENT PEAK
CURRENTS MAY BE HIGHER.
0
10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
MAX662A-03
300
280
SUPPLY CURRENT (µA)
260
240
220
200
180
160
140
120
100
4.50
4.75
5.00
5.25
T
A
= +125°C
T
A
= 0°C
T
A
= +25°C
T
A
= -55°C
12.6
12.4
12.2
OUTPUT VOLTAGE (V)
12.0
11.8
11.6
11.4
11.2
11.0
10.8
10.6
CONTINUOUS OUTPUT CURRENT MUST
NOT EXCEED 50mA ABS MAX LIMIT.
INTERMITTENT PEAK CURRENTS MAY
BE HIGHER.
V
CC
= 4.5V
V
CC
= 4.75V
V
CC
= 5.0V
V
CC
= 5.5V
100
5.50
0
10 20 30 40 50 60 70 80 90 100
OUTPUT CURRENT (mA)
SUPPLY VOLTAGE (V)
2
_______________________________________________________________________________________
+12V, 30mA Flash Memory
Programming Supply
_____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 3a, T
A
= +25°C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
LINE-TRANSIENT RESPONSE
MAX662A
A
A
0mA
0V
B
0V
B
1ms/div
A: OUTPUT CURRENT, 20mA/div, I
OUT
= 0mA to 30mA
B: OUTPUT VOLTAGE RIPPLE, 100mV/div, V
CC
= 5.0V
1ms/div
A: SUPPLY VOLTAGE, 2V/div, V
CC
= 4.5V to 5.5V, I
OUT
= 30mA
B: OUTPUT VOLTAGE RIPPLE, 200mV/div
_____________________Pin Description
PIN
1
2
3
4
5
6
7
NAME
C1-
C1+
C2-
C2+
V
CC
V
OUT
GND
FUNCTION
Negative terminal for the first charge-
pump capacitor
Positive terminal for the first charge-
pump capacitor
Negative terminal for the second
charge-pump capacitor
Positive terminal for the second
charge-pump capacitor
Supply Voltage
+12V Output Voltage. V
OUT
= V
CC
when in shutdown mode.
Ground
Active-high CMOS-logic level
Shutdown Input. SHDN is internally
pulled up to V
CC
. Connect to GND for
normal operation. In shutdown mode,
the charge pumps are turned off and
V
OUT
= V
CC
.
V
CC
C4
4.7µF
V
CC
S1
S2
V
OUT
C2-
S1
ERROR
AMP
R1
C1+
0.22µF
C1-
S1
OSCILLATOR
S1
S2
S2
VREF
SHDN
R2
C2+
0.22µF
C3*
0.1µF
+12V
C5
4.7µF
MAX662A
8
SHDN
GND
SWITCH CLOSURES SHOWN FOR CHARGE PUMP IN THE TRANSFER MODE
* C3 NOT REQUIRED. FOR MAX662 ONLY.
Figure 1. Block Diagram
_______________________________________________________________________________________
3
+12V, 30mA Flash Memory
Programming Supply
MAX662A
_______________Detailed Description
Operating Principle
The MAX662A provides a regulated 12V output voltage
at 30mA from a 5V ±5% power supply, making it ideal
for flash EEPROM programming applications. It uses
internal charge pumps and external capacitors to gen-
erate +12V, eliminating inductors. Regulation is provid-
ed by a pulse-skipping scheme that monitors the
output voltage level and turns on the charge pumps
when the output voltage begins to droop.
Figure 1 shows a simplified block diagram of the
MAX662A. When the S1 switches are closed and the
S2 switches are open, capacitors C1 and C2 are
charged up to V
CC
. The S1 switches are then opened
and the S2 switches are closed so that capacitors C1
and C2 are connected in series between V
CC
and
V
OUT
. This performs a voltage tripling function. A pulse-
skipping feedback scheme adjusts the output voltage
to 12V ±5%. The efficiency of the MAX662A with V
CC
=
5V and I
OUT
= 30mA is typically 76%. See the
Efficiency vs. Load Current graph in the
Typical
Operating Characteristics.
During one oscillator cycle, energy is transferred from
the charge-pump capacitors to the output filter capaci-
tor and the load. The number of cycles within a given
time frame increases as the load current increases or
as the input supply voltage decreases. In the limiting
case, the charge pumps operate continuously, and the
oscillator frequency is nominally 500kHz.
Shutdown Mode
The MAX662A enters shutdown mode when SHDN is a
logic high. SHDN is a TTL/CMOS-compatible input sig-
nal that is internally pulled up to V
CC
. In shutdown
mode, the charge-pump switching action is halted and
V
IN
is connected to V
OUT
through a 1kΩ switch. When
entering shutdown, V
OUT
declines to V
CC
in typically
13ms. Connect SHDN to ground for normal operation.
When V
CC
= 5V, it takes typically 400µs for the output
to reach 12V after SHDN goes low (Figure 2).
__________Applications Information
Compatibility with MAX662
The MAX662A is a 100%-compatible upgrade of the
MAX662. The MAX662A does not require capacitor C3,
although its presence does not affect performance.
Capacitor Selection
Charge-Pump Capacitors, C1 and C2
The capacitance values of the charge-pump capacitors
C1 and C2 are critical. Use ceramic or tantalum capaci-
tors in the 0.22µF to 1.0µF range. For applications requir-
ing operation over extended and/or military temperature
ranges, use 1.0µF tantalum capacitors for C1 and C2
(Figure 3b).
Input and Output Capacitors, C4 and C5
The type of input bypass capacitor (C4) and output filter
capacitor (C5) affects performance. Tantalums, ceramics
or aluminum electrolytics are suggested. For smallest size,
use Sprague 595D475X9016A7 surface-mount capacitors,
which are 3.51mm x 1.81mm. For lowest ripple, use low-
ESR through-hole ceramic or tantalum capacitors. For low-
est cost, use aluminum electrolytic or tantalum capacitors.
Figure 3a shows the component values for proper opera-
tion over the commercial temperature range using mini-
mum board space. The input bypass capacitor (C4) and
output filter capacitor (C5) should both be at least 4.7µF
when using Sprague’s miniature 595D series of tantalum
chip capacitors. Figure 3b shows the suggested compo-
nent values for applications over extended and/or mili-
tary temperature ranges.
The values of C4 and C5 can be reduced to 2µF and
1µF, respectively, when using ceramic capacitors. If
using aluminum electrolytics, choose capacitance values
of 10µF or larger for C4 and C5. Note that as V
CC
increases above 5V and the output current decreases,
the amount of ripple at V
OUT
increases due to the slower
oscillator frequency combined with the higher input volt-
age. Increase the input and output bypass capacitance
to reduce output ripple.
Table 1 lists various capacitor suppliers.
5V
0V
SHDN
12V
V
OUT
5V
200µs/div
CIRCUIT OF FIGURE 3, V
CC
= 5V, I
OUT
= 200µA
Figure 2. MAX662A Exiting Shutdown
4
_______________________________________________________________________________________
+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.
_______________________________________________________________________________________
5
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