calogic CLM7660 User Manual

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CORPORATION

DC-to-DC

Voltage Converter

CLM7660

FEATURES

•• Converts +5V Logi c Sup pl y to ±5 System

•• Wide Inpu t Voltage Ran ge . . . . . . . . . . . . . . 1.5V to 10V

•• Low Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . 500µA

•• Efficient Voltage Conversi o n . . . . . . . . . . . . . . . . . 99.9%

•• RS232 Negative Power Supply

•• Low Cost, Simple to Use

APPLICATIONS

•• A-to-D Converters

•• D-to-A Conve rter s

•• Multiplexers

•• Operat io nal Am pl ifie rs

PIN CONFIGUR ATION AND BLOCK DIAG RAM

NC 1

+

CAP

2

GND

CAP

–

CLM7660

3
45

DESCRIPTION

Calogic CL M7660 DC-to-DC convert er will ge nerate a negative
voltage from a positive source. The CLM7660 generates -5V
in +5V digital systems and with tw o exter nal cap acitor s, the dev ice
will convert a 1.5V to 10V input signal to a -1.5V to -10V level.

Applications include analog-to-digital converters, digital-to-analog
converte rs, operat ional ampli fiers and mul tiplex ers. Many of these
systems require negative supply voltages. The CLM7660 allows
+5V digital logic systems to incorporate these analog com ponent s
without an additional main power source. Lower part count, less real
estate, ease of use ar e just a few of the benefi ts of the CLM7 660.

ORDERING INFORMATION
Part Package Temperature

o

CLM7660CP 8 Pin DIP -40
CLM7660DY 8 Pin SOIC -40

+

8

V

7

OSC
LOW

6

VOLTAGE (LV)
V

OUT

C to +85oC

o

C to +85oC

NC = NO INTERNAL CONNECTION

1K-17

+

+

CAP

V

2

8

OSC

7

6

LV

RC

OSCILLATOR

INTERNAL

VOLTAGE

REGULATOR

÷2

VOLTAGE-

LEVEL

TRANSLATOR

3

GND

LOGIC

NETWORK

4

5

CAP

V

OUT

1B-35

–

CALOG IC CORPOR ATION, 237 Whitney Place, Fremont, California 94539, Telephone: [phone], FAX: [phone]

CLM7660

ABSOLUTE MAXIMUM RATINGS

Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +10.5V

L V and OSC I nput s

Volt age ( Not e 1). . . . . . . . . . . . . . . . . . . -0.3V to (V

+

-5.5V) to (V++0.3V)

(V

Current into LV (Note 1). . . . . . . . . . . . . . . 20µA for V

Output Shor t Duration (V

≤ 5.5V). . . . . . . . Continuous

SUPPLY

Power Dissipation (Note 2)

Plastic DIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375mW

for V

for V

+

+0.3V)

+

<5.5V

+

<5.5V

+

>3.5V

CORPORATION

Operating Temper at ur e Ra nge

D Suffix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40

Storage Temper at ure Ra nge. . . . . . . . . . . . . -65

o

C to +85oC

o

C to +150oC

Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300

Static - se n si t iv e de v ic e . Unu s ed dev ic e s mus t be sto r ed in co nd uctive material.
Protect devices from static discharge and static fields. Stresses above 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 above those indicated in the operation sections of
the specifications is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

o

C

ELECTRICAL CHARACTERISTIC S V+ = 5V, TA = +25oC, C

= 0, Te st Circuit (Figur e 1), unle ss otherwise indicat ed.

OSC

SYMBOL PARAMETER MIN TYP MAX UNIT TEST CONDITIONS

+

I

+

V

H1

Supply Current - 80 180 µARL = ∞
Supply Voltage Range, High 3 - 6.5 V 0oC ≤ TA ≤ +70oC, RL = 10kΩ, LV Open

3 - 5 V -55oC ≤ TA ≤ +125oC, 10kΩ, LV Open

+

V

V

V

R

f

OSC

L1

+

H2

+

L2

OUT

Supply Voltage Range, Low
(D

Out of Circu it)

X

Supply Voltage Range, High
(D

In Circuit)

X

Supply Voltage Range, Low
(D

In Circuit)

X

1.5 - 3. 5 V M in ≤ T

3 - 10 V Min ≤ T

1.5 - 3.5 V Min ≤ T

Output Source Resistance - 55 100 Ω I

--120Ω I

--300Ω V

Oscillator Frequency - 10 - kHz

≤ Max, RL = 10kΩ, LV to GND

A

≤ Max, RL = 10kΩ, LV Open

A

≤ Max, RL = 10kΩ, LV to GND

A

= 20mA, TA = 25oC

OUT

= 20mA, 0oC ≤ TA ≤ +70oC (C Device)

OUT

+

= 2V, I

o

0

C ≤ TA ≤ +70oC

= 3mA, LV to GND

OUT

PEF Power Efficiency 95 98 - % RL = 5kΩ
V

OUT EF

Z

OSC

Voltage Conversion Efficiency 97 99.9 - % RL = ∞
Oscillator Impedance - 1 - MΩ V+ = 2V

-100- kΩ V+ = 5V

NOTES:

1. Connecting any input terminal to voltages greater than C+ or less than GND may cause destructive latch-up. It is recommended that no inputs
from sources operating from external supplies be applied prior to "power up" of the CLM7660.

2. Derate linearly above 50

o

C by 5.5mW/oC.

CALOG IC CORPOR ATION, 237 Whitney Place, Fremont, California 94539, T elephone: 510-656-2900, FAX: [phone]

CORPORATION

CIRCUIT DESCRIPTION

CLM7660

The CLM7660 is an excellent voltage doubler, the device has
all the characteristic with the exception of two i nexpensive
10µF polarized electrolytic external capacitors. Figure 3
demonstrates t he most ef fect ive m eans of using the device as
a voltage doubler. Capacitor C
for the half cycle when switches S
Switches S

and S4 are open during this half cycle.) During

2

the second half of the operation, switches S
closed, with S

and S3 open, thereby shifting capacitor C

1

is charged to a voltage, V+,

1

and S3 are closed. (Note

1

and S4 are

2

negatively by V+ volts. Charge is then transferred from C1 to

, such that voltage on C2 is exactly V+, asumming ideal

C

2

switches and no load on C
The four switches in Figure 3 are MOS power switches, S

a P-Channel device, S

.

2

, S3 and S4 are N-Channel devices.

2

is

1

The major challenge with this approach while integrating the
switches, the substrates of S

and S4 must always remain

3

reversed-biased with respect to their sources, but not so
much as to degrade their ON-resistances. In addition, at
circuit start-up, and under short circuit conditions (V

OUT

=V+),
the output voltage must be sensed and the substrate bias
adjusted accordingly. Fail ure to accomplish this will result in
high power losses an d probab le device latch- u p .

The above problem is eliminated in the CLM7660 by a logic
network which senses the output voltage (V
the level translators, and switches t h e substrates of S

) together with

OUT

and S

3

to the correct le vel to ma inta in neces sar y rever se bias.
The voltage regulator portion of the CLM7660 is an integral

part of the anti-latch-up circuitr y. Its inherent voltage d ro p ca n
degrade operation at low voltages. To improve low-voltage
operation, the LV pin should be connected to GND, disabling
the regulator. For supply voltages greater than 3.5V, the LV
terminal must be left open to ensure latch-up proof operation
and prevent device damage.

When larger values of C

and C2 are used, the CLM7660

1

approaches the above conditions for negative voltage
multiplication.

Energy is lost only if the transfer of the charge
between capacitors if a change in voltage oc cur s. The energ y
lost is defin ed by:

E=1/2C
During the pump and transfer cycles V

voltages on C

1

(V12-V22)

1

1

and V2 are the

1

. If the impedances of C1 and C2 are high at
the pump frequency (see Fi gure 3), compared to the value of
R

, there will be a substantial difference i n voltages V1 and

L

. The most optimum selection would be to make C2 as

V

2

large as possible to eliminate output voltage ripple, and to
utilize a large value for C

to achieve maximum efficiency of

1

operation.

OPERATIONAL RULES:

Never exceed maxim um supp ly voltages.
Never connect LV terminal to GND for supply voltages over

3.5V.
Never short circuit the output to V

+

supply voltages above

5.5V for extended periods; however, transient conditions
including start-up are accept ab le.

For polarized capacitors, the + terminal of C

4

connected to pin 2 of the CLM7660 and the + ter minal t o o f C
must be connected to GND.

For high-voltage, elevated temperature applications add a
diode D

(reference Figure 1). The 1N914 diode is an

X

appropriate choice.

must be

1

2

THEORETICAL PO WER E FF ICI ENCY CONSIDERATIONS

In theory, a voltage multiplier can approach 100% efficiency if
certain conditions are met :

1. The drive circuitr y consum es minim al power.

2. The output switches have extremely low ON-resistance and
virtually no of f set .

3. The impedances of the pump and reservoir capacitor s are
negligible at the pump frequency.

CALOG IC CORPOR ATION, 237 Whitney Place, Fremont, California 94539, T elephone: 510-656-2900, FAX: [phone]