Microchip Technology TC7660HEPA, TC7660HEOA, TC7660HCPA, TC7660HCOA Datasheet

EVALUATION

KIT

AVAILABLE

HIGH FREQUENCY 7660 DC-TO-DC VOLTAGE CONVERTER

G

TC7660H

FEATURES

■ Pin Compatible with 7660, High Frequency

Performance DC-to-DC Converter

■ Low Cost, Two Low Value External Capacitors

Required ........................................................ (1.0µF)

■ Converts +5V Logic Supply to ±5V System

■ Wide Input Voltage Range .................... 1.5V to 10V

■ Voltage Conversion........................................99.7%

■ Power Efficiency................................................85%

■ Available in 8-Pin SOIC and 8-Pin PDIP Packages

PIN CONFIGURATION (DIP and SOIC)

NC

CAP

ND

CAP

CAP

GND

CAP

NC

1

+

2

TC7660HCPA

3
4

1
2
3
4

TC7660HEPA

TC7660HCOA
TC7660HEOA

–

+

–

+

8

V

OSC

7

LOW

6

VOLTAGE (LV)

V

5

OUT

+

V

8

OSC

7

LOW

6

VOLTAGE (LV)

5

V

OUT

GENERAL DESCRIPTION

The TC7660H is a pin-compatible, high frequency up­grade to the Industry standard TC7660 charge pump volt­age converter. It converts a +1.5V to +10V input to a
corresponding – 1.5V to – 10V output using only two low­cost capacitors, eliminating inductors and their associated
cost, size and EMI.

The TC7660H operates at a frequency of 120kHz
(versus 10kHz for the TC7660), allowing the use of 1.0µF
external capacitors. Oscillator frequency can be reduced
(for lower supply current applications) by connecting an
external capacitor from OSC to ground.

The TC7660H is available in 8-pin DIP and small
outline (SOIC) packages in commercial and extended
temperature ranges.

ORDERING INFORMATION

Temperature

Part No. Package Range

TC7660HCOA 8-Pin SOIC 0°C to +70°C
TC7660HCPA 8-Pin Plastic DIP 0°C to +70°C
TC7660HEOA 8-Pin SOIC – 40°C to +85°C
TC7660HEPA 8-Pin Plastic DIP – 40°C to +85°C

TC7660EV Evaluation Kit for

Charge Pump Family

NC = NO INTERNAL CONNECTION

FUNCTIONAL BLOCK DIAGRAM

OSC

LV

© 2001 Microchip Technology Inc. DS21466A

7

OSCILLATOR

6

TC7660H

RC

INTERNAL

VOLTAGE

REGULATOR

÷ 2

VOLTAGE–

LEVEL

TRANSLATOR

V+CAP

82

3

GND

+

LOGIC

NETWORK

4

5

CAP

V

OUT

–

TC7660H-2 10/1/96

TC7660H

HIGH FREQUENCY 7660 DC-TO-DC

VOLTAGE CONVERTER

ABSOLUTE MAXIMUM RATINGS*

Operating Temperature Range

C Suffix ..................................................0°C to +70°C

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

LV and OSC Inputs

Voltage (Note 1) ........................ – 0.3V to (V+ + 0.3V)

E Suffix ............................................ – 40°C to +85°C

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

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

for V+ < 5.5V

(V+ – 5.5V) to (V+ + 0.3V)

for V+ > 5.5V

Current Into LV (Note 1)..................... 20µA for V+ > 3.5V

Output Short Duration (V

≤ 5.5V) .........Continuous

SUPPLY

Power Dissipation (TA ≤ 70°C) (Note 2)

SOIC...............................................................470mW

Plastic DIP ......................................................730mW

ELECTRICAL CHARACTERISTICS: Over Operating Temperature Range with V

*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 operation sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.

+

= 5V, CI = C2 = 1µF, C

OSC

= 0,

Test Circuit (Figure 1), unless otherwise indicated.

Symbol Parameter Test Conditions Min Typ Max Unit

+

I

+

V

H

+

V

L

R

OUT

F

OSC

P

EFF

V

EFF

NOTES: 1. Connecting any input terminal to voltages greater than V+ or less than GND may cause destructive latch-up. It is recommended that no

Supply Current RL = ∞ — 0.46 1.0 mA
Supply Voltage Range, High Min ≤ TA ≤ Max, 3 — 10 V

RL = 5kΩ, LV Open

Supply Voltage Range, Low Min ≤ TA ≤ Max, 1.5 — 3.5 V

RL = 5kΩ, LV to GND

Output Source Resistance I

= 20mA, TA = 25°C — 55 80 Ω

OUT

I

= 20mA, 0°C ≤ TA ≤ +70°C——95Ω

OUT

(C Device)
I

= 20mA, – 40°C ≤ TA ≤ +85°C — — 110 Ω

OUT

(E Device)

+

V

= 2V, I

= 3mA, LV to GND — 150 250 Ω

OUT

0°C ≤ TA ≤ +70°C
Oscillator Frequency — 120 — kHz
Power Efficiency I

= 10mA, Min ≤ TA ≤ Max 81 85 — %

OUT

Voltage Efficiency RL = ∞ 99 99.7 — %

inputs from sources operating from external supplies be applied prior to "power up" of the TC7660H.

2. Derate linearly above 50°C by 5.5mW/°C.

TC7660H-2 10/1/96

2

© 2001 Microchip Technology Inc. DS21466A

HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER

I

S

+

V

(+5V)

2

R

L

C

1.0 µF

1
2

+

1

TC7660H

3
4

Figure 1. TC7660H Test Circuit

8
7
6
5

C

1.0 µF

+

Detailed Description

The TC7660H contains all the necessary circuitry to
implement a voltage inverter, with the exception of two
external capacitors, which may be inexpensive 1.0µF
non-polarized capacitors. Operation is best understood by
considering Figure 2, which shows an idealized voltage
inverter. Capacitor C1 is charged to a voltage, V+, for the half
cycle when switches S1 and S3 are closed. (Note: Switches
S2 and S4 are open during this half cycle.) During the second
half cycle of operation, switches S2 and S4 are closed, with
S1 and S3 open, thereby shifting capacitor C1 negatively by
V+ volts. Charge is then transferred from C1 to C2, such that
the voltage on C2 is exactly V+, assuming ideal switches and
no load on C2.

TC7660H

To improve low-voltage operation, the LV pin should be
connected to GND. For supply voltages greater than 3.5V,
the LV terminal must be left open to ensure latch-up-

proof operation and prevent device damage.

Theoretical Power Efficiency Considerations

In theory, a capacitative charge pump can approach
100% efficiency if certain conditions are met:

(1) The drive circuitry consumes minimal power.

(2) The output switches have extremely low ON

resistance and virtually no offset.

(3) The impedances of the pump and reservoir

capacitors are negligible at the pump frequency.

The TC7660H approaches these conditions for nega­tive voltage multiplication if large values of C1 and C2 are
used. Energy is lost only in the transfer of charge
between capacitors if a change in voltage occurs. The
energy lost is defined by:

2

E = 1/2 C1 (V

1

V1 and V2 are the voltages on C1 during the pump and
transfer cycles. If the impedances of C1 and C2 are relatively
high at the pump frequency (refer to Figure 1), compared to
the value of RL, there will be a substantial difference in
voltages V1 and V2. Therefore, it is not only desirable to
make C2 as large as possible to eliminate output voltage
ripple, but also to employ a correspondingly large value for
C1 in order to achieve maximum efficiency of operation.

Do's and Don'ts

• Do not exceed maximum supply voltages.

– V

2

)

2

S

+

V

GND

Figure 2. Idealized Charge Pump Inverter

© 2001 Microchip Technology Inc. DS21466A

1

S

3

• Do not connect LV terminal to GND for supply voltages

S

2

greater than 3.5V.

• Do not short circuit the output to V+ supply for voltages

above 5.5V for extended periods; however, transient
conditions including start-up are okay.

C

S

2

4

V

OUT

= – V

IN

• When using polarized capacitors in the inverting mode,

the + terminal of C1 must be connected to pin 2 of the
TC7660H and the + terminal of C2 must be connected
to GND Pin 3.

3

TC7660H-2 10/1/96

TC7660H

HIGH FREQUENCY 7660 DC-TO-DC

VOLTAGE CONVERTER

Simple Negative Voltage Converter

Figure 3 shows typical connections to provide a nega­tive supply where a positive supply is available. A similar
scheme may be employed for supply voltages anywhere in
the operating range of +1.5V to +10V, keeping in mind that
pin 6 (LV) is tied to the supply negative (GND) only for supply
voltages below 3.5V.

The output characteristics of the circuit in Figure 3 are
those of a nearly idea l voltage source in series with 70Ω.
Thus, for a load current of – 10 mA and a supply voltage of
+5V, the output voltage would be – 4.3V.

The dynamic output impedance of the TC7660H is due,
primarily, to capacitive reactance of the charge transfer
capacitor (C1). Since this capacitor is connected to the
output for only 1/2 of the cycle, the equation is:

XC = = 2.12Ω,

where f = 150kHz and C1 = 1.0µF.

2

2πf C

1

+

V

+

V

C

1.0 µF

*

1
2

+

1

TC7660H

3
4

1. V

Figure 3. Simple Negative Converter

OUT

= –n V+for 1.5V V+ 10VNOTES:

8
7
6
5

V

*

OUT

C

2

1.0 µF

+

Paralleling Devices

Any number of TC7660H voltage converters may be
paralleled to reduce output resistance (Figure 4). The reser­voir capacitor, C2, serves all devices, while each device
requires its own pump capacitor, C1. The resultant output
resistance would be approximately:

R

(of TC7660H)

R

OUT

=

OUT

n (number of devices)

1.0 µF

NOTES:

*

1. V

OUT

1
2

+

= –n V+for 1.5V V 10V

TC7660H

3
4

"1"

8
7
6
5

+

Figure 4. Increased Output Voltage by Cascading Devices

1.0 µF

Cascading Devices

The TC7660H may be cascaded as shown in (Figure 4)
to produce larger negative multiplication of the initial supply
voltage. However, due to the finite efficiency of each device,
the practical limit is probably 10 devices for light loads. The
output voltage is defined by:

V

= – n (VIN)

OUT

where n is an integer representing the number of devices
cascaded. The resulting output resistance would be ap­proximately the weighted sum of the individual TC7660H
R

values.

OUT

TC7660H-2 10/1/96

1
2

+

3
4

TC7660H

"n"

8
7
6
5

1.0 µF

+

V

OUT

*

Changing the TC7660H Oscillator Frequency

It may be desirable in some applications (due to noise or
other considerations) to increase or decease the oscillator
frequency. This can be achieved by overdriving the oscilla­tor from an external clock, as shown in Figure 6. In order to
prevent possible device latch-up, a 1kΩ resistor must be
used in series with the clock output. In a situation where the
designer has generated the external clock frequency using
TTL logic, the addition of a 10kΩ pull-up resistor to V+ supply
is required. Note that the pump frequency with external
clocking, as with internal clocking, will be 1/2 of the clock
frequency. Output transitions occur on the positive-going
edge of the clock.

4

© 2001 Microchip Technology Inc. DS21466A

HIGH FREQUENCY 7660 DC-TO-DC

C

S

1
2
3
4

8
7
6
5

+

V

+

V

OUT

=

(2 V+) – (2 VF)

C

1

D

1

+

+

C

3

C

4

V

OUT

=

–(V+–VF)

C

2

TC7660H

D

2

+

VOLTAGE CONVERTER

+

V

1

8

TC7660H

1.0 µF

2

C

1

1
2

+

3
4

TC7660H

3

"1"

4

TC7660H

Figure 6. External Clocking

7
6
5

Figure 5. Paralleling Devices Lowers Output Impedance

+

V

8

1 kΩ

7
6
5

V

1.0 µF

+

+

CMO
GATE

V

OUT

C

1

1
2

TC7660H

3
4

Combined Negative Voltage Conversion
and Positive Supply Multiplication

Figure 8 combines the functions shown in Figures 3 and
8 to provide negative voltage conversion and positive volt­age multiplication simultaneously. This approach would be,
for example, suitable for generating +9V and –5V from an
existing +5V supply. In this instance, capacitors C1 and C
perform the pump and reservoir functions, respectively, for
the generation of the negative voltage, while capacitors C
and C4 are pump and reservoir, respectively, for the multi-

"n"

8

R

7
6
5

L

+

3

2

plied positive voltage. There is a penalty in this configuration

Positive Voltage Multiplication

The TC7660H may be employed to achieve positive
voltage multiplication using the circuit shown in Figure 7. In
this application, the pump inverter switches of the TC7660H
are used to charge C1 to a voltage level of V+ – VF (where V

which combines both functions, however, in that the source
impedances of the generated supplies will be somewhat
higher due to the finite impedance of the common charge
pump driver at pin 2 of the device.

+

is the supply voltage and VF is the forward voltage drop of
diode D1). On the transfer cycle, the voltage on C1 plus the
supply voltage (V+) is applied through diode D2 to capacitor
C2. The voltage thus created on C2 becomes (2 V+) – (2 VF),
or twice the supply voltage minus the combined forward
voltage drops of diodes D1 and D2.

The source impedance of the output (V

) will depend

OUT

on the output current, but for V+ = 5V and an output current
of 10mA, it will be approximately 60Ω.

© 2001 Microchip Technology Inc. DS21466A

1
2

TC7660H

3
4

Figure 7. Positive Voltage Multiplier

8
7
6
5

+

V

D

1

+

C

1

D

2

V

OUT

(2 V+) – (2 VF)

+

C

=

2

Figure 8. Combined Negative Converter and Positive Multiplier

5

TC7660H-2 10/1/96

TC7660H

HIGH FREQUENCY 7660 DC-TO-DC

VOLTAGE CONVERTER

Efficient Positive Voltage Multiplication/
Conversion

Since the switches that allow the charge pumping op­eration are bidirectional, the charge transfer can be per­formed backwards as easily as forwards. Figure 9 shows a
TC7660H transforming –5V to +5V (or +5V to +10V, etc.).
The only problem here is that the internal clock and switch­drive section will not operate until some positive voltage has

C

1.0 µF

1

1
2

+

3
4

been generated. An initial inefficient pump, as shown in
Figure 9, could be used to start this circuit up, after which it
will bypass the diode and resistor shown dotted in
Figure 9.

Figure 9. Positive Voltage Conversion

TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 1)

Output Source Resistance vs. Supply Voltage

10k

1k

TA = +25°C

Output Source Resistance vs. Temperature

500

I

= 1 mA

OUT

450

400

200

TC7660H

1 MΩ

= –V

V

–

–

INPUT

+

1.0 µF

V

OUT

8
7
6
5

100Ω

OUTPUT SOURCE RESISTANCE (Ω)

10Ω

OUTPUT VOLTAGE (V)

–10

TC7660H-2 10/1/96

6543210

SUPPLY VOLTAGE (V) TEMPERATURE (°C)

Output Voltage vs. Output Current

µF

=1

C

I C2

0

–1
–2
–3

–4
–5

–6
–7

–8
–9

10 20 30 40 50 60 70 80 90 100

0

OUTPUT CURRENT (mA)

TA = +25°C
LV OPEN

78

150

V+ = +2V

100

V + = +5V

50

OUTPUT SOURCE RESISTANCE (Ω)

0

–55 –25 0 +25 +50 +75 +100 +125

Output Voltage vs. Load Current

5

TA = +25°C

4

V+ = +5V

3
2
1
0

–1
–2

OUTPUT VOLTAGE (V)

–3
–4

–5

10 20 30 40 50 60 70 80

0

6

SLOPE 55Ω

LOAD CURRENT (mA)

© 2001 Microchip Technology Inc. DS21466A

HIGH FREQUENCY 7660 DC-TO-DC
VOLTAGE CONVERTER

PACKAGE DIMENSIONS

TC7660H

8-Pin Plastic DIP

.200 (5.08)
.140 (3.56)

.150 (3.81)
.115 (2.92)

8-Pin SOIC

.045 (1.14)
.030 (0.76)

.400 (10.16)

.348 (8.84)

.110 (2.79)
.090 (2.29)

.070 (1.78)
.040 (1.02)

.022 (0.56)
.015 (0.38)

PIN 1

.260 (6.60)
.240 (6.10)

.040 (1.02)
.020 (0.51)

.015 (0.38)
.008 (0.20)

.310 (7.87)
.290 (7.37)

3° MIN.

.400 (10.16)

.310 (7.87)

.050 (1.27) TYP.

.197 (5.00)
.189 (4.80)

.020 (0.51)
.013 (0.33)

.157 (3.99)
.150 (3.81)

.010 (0.25)
.004 (0.10)

.244 (6.20)
.228 (5.79)

.069 (1.75)
.053 (1.35)

8° MAX.

.010 (0.25)
.007 (0.18)

.050 (1.27)
.016 (0.40)

Dimensions: inches (mm)

© 2001 Microchip Technology Inc. DS21466A

7

TC7660H-2 10/1/96

TC7660H

HIGH FREQUENCY 7660 DC-TO-DC

W

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VOLTAGE CONVERTER

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TC7660H-2 10/1/96

8

© 2001 Microchip Technology Inc. DS21466A