Datasheet TC962MJA, TC962IJA, TC962EPA, TC962CPA, TC962COE Datasheet (TelCom Semiconductor)

HIGH CURRENT CHARGE PUMP DC-TO-DC CONVERTER

EVALUATION

KIT

AVAILABLE

1

TC962

FEATURES

■ Pin Compatible With TC7662/ICL7662/SI7661

■ High Output Current ....................................... 80mA

■ No External Diodes Required

■ Wide Operating Range ............................. 3V to 18V

■ Low Output Impedance .............................28Ω Typ.

■ No Low Voltage Terminal Required

■ Application Zener On Chip

■ OSC Frequency Doubling Pin Option for Smaller

Output Capacitors

PIN CONFIGURATIONS (DIP and SOIC)

8-Pin DIP

ZENER

CATHODE

GND

ZENER

CATHODE

NC

+

C

NC

GND

NC

–

C

NC

FUNCTIONAL BLOCK DIAGRAM

TELCOM SEMICONDUCTOR, INC.

+

C

–

C

16-Pin SOIC Wide

1
2
3
4
5
6
7
8

8-Pin CerDIP

1
2
3
4

•

TC962CPA
TC962EPA

TC962IJA

TC962MJA

TC962COE

FREQ X 2

OSC/C

TIMING

ZENER

CATHODE

8

V

DD

C

7

OSC

6

FREQ x 2

V

5

OUT

16

V

DD

15

NC

14

C

OSC

13

NC

12

FREQ x 2

11

NC

10

V

OUT

9

NC

6

–

7

1

I

I

+
–

COMPARATOR
WITH HYSTERESIS

6.4V

Q

F/F

C

Q

V

REF

GENERAL DESCRIPTION

The TC962 is an advanced version of the industry­standard 7662 high-voltage DC-to-DC converter. Using
improved design techniques and CMOS construction, the
TC962 can source as much as 8mA versus the 7662’s
20mA capability.

As an inverter, the TC962 can put out voltages as high
as 18V and as low as 3V without the need for external
diodes. The output impedance of the device is a low 28Ω
(with the proper capacitors), voltage conversion efficiency
is 99.9%, and power conversion efficiency is 97%.

The low voltage terminal (pin 6) required in some 7662
applications has been eliminated. Grounding this terminal
will double the oscillator frequency from 12kHz to 24kHz.
This will allow the use of smaller capacitors for the same
output current and ripple, in most applications. Only two
external capacitors are required for inverter applications. In
the event an external clock is needed to drive the TC962
(such as paralleling), driving this pin directly will cause the
internal oscillator to sync to the external clock.

ORDERING INFORMATION

Part No. Package Temp. Range

TC962COE 16-Pin SOIC Wide 0°C to +70°C
TC962CPA 8-Pin Plastic DIP 0°C to +70°C
TC962EPA 8-Pin Plastic DIP – 40°C to +85°C
TC962IJA 8-Pin CerDIP – 25°C to +85°C
TC962MJA 8-Pin CerDIP – 55°C to +125°C

TC7660EV Evaluation Kit for Charge Pump Family

8

V

DD

TC962

LEVEL

SHIFT

LEVEL

SHIFT

LEVEL

SHIFT

LEVEL

SHIFT

P SW1

N SW4

N SW2

N SW3

2

+

4

+

CAP

C

P

EXTERNAL

OUT

–

CAP

GND

3

+

C

R

EXT

R

L

5
V

OUT

TC962-8 9/16/96

2

3

4

5

6

7

8

4-37

TC962

HIGH CURRENT CHARGE PUMP

DC-TO-DC CONVERTER

Pin 1, which is used as a test pin on the 7662, is a voltage
reference zener on the TC962. This zener (6.4V at 5 mA) has
a dynamic impedance of 12Ω and is intended for use where
the TC962 is supplying current to external regulator circuitry
and a reference is needed for the regulator circuit. (See
applications section.)

The TC962 is compatible with the LTC1044, SI7661,
and ICL7662. It should be used in designs that require
greater power and/or less input to output voltage drop. It
offers superior performance over the ICL7660S.

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage (VDD to GND) .................................. +18V

Input Voltage Any Pin............... (VDD + 0.3) to (VSS – 0.3)

Current Into Any Pin.................................................10mA

ESD Protection..................................................... ±2000V

Output Short Circuit................. Continuous (at 5.5V Input)

Storage Temperature Range ................– 65°C to +150°C

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

Operating Temperature Range

CPA, COE .............................................0°C to +70°C

IJA ....................................................– 25°C to +85°C

EPA ..................................................– 40°C to +85°C

MJA ................................................– 55°C to +125°C

Package Power Dissipation (TA ≤ 70°C)

SOIC...............................................................760mW

PDIP ...............................................................730mW

CerDIP............................................................800mW

Package Thermal Resistance

CerDIP, R
PDIP, R

*Static-sensitive device. Unused devices must be stored in conductive
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 operational sections of the specifications is not implied.
Exposure to Absolute Maximum Rating Conditions for extended periods
may affect device reliability.

................................................ 90°C/W

θJ-A

................................................. 140°C/W

θJ-A

ELECTRICAL CHARACTERISTICS: V

= 15V, TA = +25°C (See Test Circuit), unless otherwise indicated.

DD

Symbol Parameter Test Conditions Min Typ Max Unit

V
I

R

C

P

V

V
Z

DD

S

O

OSC

EFF

DEF

Z

ZT

Supply Voltage 3 18 V
Supply Current RL = ∞

V

= 15V TA = +25°C 510 700 µA

DD

= 5V TA = +25°C 190 µA

V

DD

Output Source IL = 20mA, VDD = 15V — 32 37 Ω
Resistance I

Oscillator Frequency Pin 6 Open — 12 — kHz

Power Efficiency VDD = 15V 93 97 — %

Voltage Efficiency VDD = 15V 99 99.9 — %

Zener Voltage IZ = 5mA 6.0 6.2 6.4 V
Zener Impedance IL = 2.5mA to 7.5mA — 12 Ω

≤ +70°C 560 µA

0 ≤ T

A

–55 ≤ T
0 ≤ T

–55 ≤ TA ≤ +125°C 210 µA

L

IL = 3mA, VDD = 5V — 50 Ω

Pin 6 GND 24 kHz

RL = 2 kΩ

R
Over Temperature Range 96 — %

≤ +125°C 650 µA

A

< +70°C 210 µA

A

= 80mA, VDD = 15V 35 40 Ω

= ∞

L

——— —

4-38

TELCOM SEMICONDUCTOR, INC.

HIGH CURRENT CHARGE PUMP
DC-TO-DC CONVERTER

1

TC962

APPLICATIONS INFORMATION
Theory of Operation

The TC962 is a capacitive pump (sometimes called a
switched capacitor circuit), where four MOSFET switches
control the charge and discharge of a capacitor.

The functional diagram (page 1) shows how the switch­ing action works. SW1 and SW2 are turned on simulta­neously, charging CP to the supply voltage, VIN. This as­sumes that the on resistance of the MOSFETs in series
with the capacitor results in a charging time (3 time con­stants) that is less than the on time provided by the oscilla­tor frequency as shown:

3 (R

DS(ON) CP

In the next cycle, SW1 and SW2 are turned off and
after a very short interval of all switches being off (this
prevents large currents from occurring due to cross con­duction), SW3 and SW4 are turned on. The charge in CP is
then transferred to CR, BUT WITH THE POLARITY IN­VERTED. In this way, a negative voltage is now derived.

Page 1 shows a functional diagram of the TC962. An
oscillator supplies pulses to a flip-flop that is then fed to a
set of level shifters. These level shifters then drive each set
of switches at one-half the oscillator frequency.

The oscillator has two pins that control the frequency of
oscillation. Pin 7 can have a capacitor added that is re­turned to ground. This will lower the frequency of the
oscillator by adding capacitance to the timing capacitor
internal to the TC962. Grounding pin 6 will turn on a
current source and double the frequency. This will double
the charge current going into the internal capacitor, as well
as any capacitor added to pin 7.

A zener diode has been added to the TC962 for use as
a reference in building external regulators. This zener runs
from pin 1 to ground.

) <CP/(0.5 f

OSC

)

This applies to all types of capacitors, including film

types (polyester, polycarbonate, etc.).

Some applications information suggest that the capaci­tor is not critical and attribute the limiting factor of the
capacitor to its reactive value. Let's examine this:

XC = and ZC = ,

where DS (duty cycle) = 50%.

Thus, ZC ≈ 2.6Ω at f = 12kHz, where C = 10µF.

For the TC962, f = 12,000 Hz, and a typical value of C
would be 10µF. This is a reactive impedance of ' 2.6Ω. If
the ESR is as great as 5Ω, the reactive value is not as critical
as it would first appear, as the ESR would predominate.
The 5Ω value is typical of a general-purpose electrolytic
capacitor.

ESL

Figure 1. Typical Electrolytic Capacitor

1

2πf C

ESR

X

DS

C

C

Latch Up

All CMOS structures contain a parasitic SCR. Care must
be taken to prevent any input from going above or below the
supply rail, or latch up will occur. The result of latch up is an
effective short between VDD and VSS. Unless the power
supply input has a current limit, this latch-up phenomena will
result in damage to the device. (See Application Note 31 for
additional information.)

TEST CIRCUIT

2

3

4

5

6

Capacitors

In early charge pump converters, the capacitors were
not considered critical due to the high R
FET switches. In order to understand this, let’s look at a
model of a typical electrolytic capacitor (Figure 1).

Note that one of its characteristics is ESR (equivalent
series resistance). This parasitic resistance winds up in
series with the load. Thus, both voltage conversion effi­ciency and power conversion efficiency are compromised if
a low ESR capacitor is not used.

In the test circuit, for example, just changing two capaci­tors, CP and CR, from capacitors with unspecified ESR to low
ESR-type output, impedance changes from 36Ω to 28Ω, an
improvement of 23%!

TELCOM SEMICONDUCTOR, INC.

DS(ON)

of the MOS-

NC

C

690Ω

I

+

S

I

L

R

L

10µF

V
(+5V)

V

OUT

(–5V)

7

1
2

+

10µF

3

P

TC962

4

8
7

C

OSC

5

C

R

+

8

4-39

TC962

TYPICAL APPLICATIONS

HIGH CURRENT CHARGE PUMP

DC-TO-DC CONVERTER

Combined Negative Converter and Positive Multiplier

+

V

1
2

+

10µF

C

P2

3
4

C 1

P

TC962

+

8
7

6

V = –V

OUT

5

+

10µF

V

D1

V

D2

+

C

R1

+

V =

OUT

+

2V –2V

10µF

C

D

P

Lowering Output Resistance by Paralleling Devices

+

V

8
7

6
5

V

C

R

OUT

10µF

+

+

10µF

1
2

3
4

1
2

10µF+

C

P1

3

TC962 TC962

4

8
7

C

6

P2

5

1
2

3
4

Split V In Half

10µF

+

Positive Voltage Multiplier

TC962

+

+

V
1
2

3

TC962

4

8
7

6
5

8
7

6
5

+

OUT

10µF

V
2

V =

OUT

+

2V –2 V

D

10µF

V

D2

C

P

V =

++

+

C

R

+

V

V

D1

10µF

C

P

4-40

TELCOM SEMICONDUCTOR, INC.

(V)

HIGH CURRENT CHARGE PUMP
DC-TO-DC CONVERTER

TYPICAL CHARACTERISTICS

1

TC962

Supply Current vs. Temperature

700

600

500

+

400

300

200

SUPPLY CURRENT (µA)

100

0

–40 –20 0 20 40 60 80 100

–60

TEMPERATURE (°C)

V = 15V

+

V = 15V

Output Resistance vs. Temperature

80

70

Ω

60

+

V = 5V I = 3mA

50

40

30

OUTPUT RESISTANCE ( )

20

10

–60 –40 –20 0 20 40 60 80 100 120 140

L

+

V = 15V I = 20mA

TEMPERATURE (°C)

L

120 140

Oscillator Frequency vs. C

10k

1k

100

FREQUENCY (Hz)

10

10 100 1000 10,000

1

CAPACITANCE (pF)

Current vs. Zener Voltage

TA = +25°C

50

40

30

20

CURRENT (mA)

10

0

4.0

4.5

5.5 6.0 6.5 7.0

ZENER VOLTAGE (V)

EXT

TA = +25°C

Frequency vs. Temperature

20

18

16

14

12

10

FREQUENCY (kHz)

8

6

–60 –40 –20 0 20 40 60 80 100 120 140

TEMPERATURE (°C)

Power Conversion Efficiency vs. I

100

90

EFFICIENCY

80
70
60

50
40
30
20

10

POWER CONVERSION EFFICIENCY (%)

0

824405672

16

TA = +25°C

SUPPLY
CURRENT

32 48 64 80

LOAD CURRENT (mA)

LOAD

150
135

120
105
90
75

60

45

SUPPLY CURRENT (mA)

30
15
0

2

3

4

5

Output Resistance vs. Input Voltage

110
100

90

Ω

80
70

3mA

60
50
40
30

OUTPUT RESISTANCE ( )

20
10

20mA

2 6 10 14 180

4 8 12 16 20

INPUT VOLTAGE

TA = +25°C

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6

7

8

4-41