Datasheet TC7662BCOA, TC7662BEPA, TC7662BEOA, TC7662BCPA Datasheet (TelCom Semiconductor)

CHARGE PUMP DC-TO-DC VOLTAGE CONVERTER

EVALUATION

KIT

AVAILABLE

1

TC7662B

FEATURES

■ Wide Operating Voltage Range: 1.5V to 15V

■ Boost Pin (Pin 1) for Higher Switching Frequency

■ High Power Efficiency is 96%

■ Easy to Use – Requires Only 2 External Non-Critical

Passive Components

■ Improved Direct Replacement for Industry Stan-

dard ICL7660 and Other Second Source Devices

APPLICATIONS

■ Simple Conversion of +5V to ±5V Supplies

■ Voltage Multiplication V

■ Negative Supplies for Data Acquisition Systems

and Instrumentation

■ RS232 Power Supplies

■ Supply Splitter, V

OUT

= ±VS/2

PIN CONFIGURATION (DIP and SOIC)

BOOST

CAP

GND

CAP

1

+

2
3

–

4

TC7662BCPA
TC7662BEPA

+

8

V

7

OSC
LOW

6

VOLTAGE (LV)

5

V

OUT

OUT

BOOST

CAP

GND

CAP

= ±nV

1

+

2

TC7662BCOA

3

TC7662BEOA

–

4

IN

+

8

V

7

OSC
LOW

6

VOLTAGE (LV)

5

V

OUT

GENERAL DESCRIPTION

The TC7662B is a pin-compatible upgrade to the Indus­try standard TC7660 charge pump voltage converter. It
converts a +1.5V to +15V input to a corresponding – 1.5 to
– 15V output using only two low-cost capacitors, eliminating
inductors and their associated cost, size and EMI.

The on-board oscillator operates at a nominal fre­quency of 10kHz. Frequency is increased to 35kHz when
pin 1 is connected to V+, allowing the use of smaller external
capacitors. Operation below 10kHz (for lower supply current
applications) is also possible by connecting an external
capacitor from OSC to ground (with pin 1 open).

The TC7662B is available in both 8-pin DIP and 8-pin
small outline (SO) packages in commercial and extended
temperature ranges.

ORDERING INFORMATION

Temperature

Part No. Package Range

TC7662BCOA 8-Pin SOIC 0°C to +70°C
TC7662BCPA 8-Pin Plastic DIP 0°C to +70°C
TC7662BEOA 8-Pin SOIC – 40°C to +85°C
TC7662BEPA 8-Pin Plastic DIP – 40°C to +85°C

TC7660EV Evaluation Kit for

Charge Pump Family

2

3

4

5

FUNCTIONAL BLOCK DIAGRAM

LV

1

7

6

TC7662B

BOOST

OSC

TELCOM SEMICONDUCTOR, INC.

RC

OSCILLATOR

÷ 2

INTERNAL

VOLTAGE

REGULATOR

VOLTAGE–

LEVEL

TRANSLATOR

V+CAP

82

3

GND

+

6

LOGIC

NETWORK

4

5

CAP

V

OUT

–

7

8

TC7662B-8 9/11/96

4-83

TC7662B

CHARGE PUMP DC-TO-DC

VOLTAGE CONVERTER

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage ...................................................... +16.5V

LV, Boost and OSC Inputs Voltage (Note 1)

V+<5.5V.....................................– 0.3V to (V+ + 0.3V)

>5.5V .................................. (V+ – 5.5V) to (V+ + 0.3V)

Current Into LV (Note 1)

V+ >3.5V .............................................................20µA

Output Short Duration

(V

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

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

SO ..................................................................470mW

ELECTRICAL CHARACTERISTICS: V

≤ 5.5V).......................................Continuous

SUPPLY

+

= 5V, TA = +25°C, OSC = Free running, Test Circuit Figure 2, Unless

Operating Temperature Range

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

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

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

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

*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.

Otherwise Specified.

Symbol Parameter Test Conditions Min Typ Max Unit

+

I

+

I

+

V

H

+

V

L

Supply Current (Note 3) RL = ∞, +25°C — 80 160 µA
(Boost pin OPEN OR GND) 0°C ≤ TA ≤ +70°C — — 180 µA

– 40°C ≤ TA ≤ +85°C — — 180 µA
– 55°C ≤TA ≤ +125°C — — 200 µA

Supply Current 0°C ≤ TA ≤ +70°C — — 300 µA
(Boost pin = V+) – 40°C ≤ T

≤ +85°C 350

A

– 55°C ≤ TA ≤ +125°C 400

Supply Voltage Range, High RL = 10 kΩ, LV Open, T

≤ TA ≤ T

MIN

MAX

3.0 — 15 V

(Note 4)
Supply Voltage Range, Low RL = 10 kΩ, LV to GND, T

≤ TA ≤ T

MIN

MAX

1.5 — 3.5 V

R

OUT

f

OSC

P

Eff

V

Eff Voltage Conversion Efficiency RL = ∞ 99 99.9 — %

OUT

Z

OSC

Output Source Resistance I

Oscillator Frequency C

= 20 mA, 0°C ≤ TA ≤ +70°C — 65 100 Ω

OUT

I

= 20 mA, – 40°C ≤ TA ≤ +85°C — — 120 Ω

OUT

I

= 20 mA, - 55°C ≤ TA ≤ +125°C — — 150 Ω

OUT

I

= 3 mA, V+ = 2V, LV to GND , — — 250 Ω

OUT

0°C ≤ T
I

OUT

– 40°C ≤ T
I

OUT

– 55°C ≤ T

≤ +70°C

A

= 3 mA, V+ = 2V, LV to GND , — — 300 Ω

≤ +85°C

A

= 3 mA, V+ = 2V, LV to GND , — — 400 Ω

≤ +125°C

A

= 0, Pin 1 Open or GND 5 10 — kHz

OSC

Pin 1 = V

+

35

Power Efficiency RL = 5 kΩ 96 96 — %

T

≤ TA ≤ T

MIN

MAX

95 97

Oscillator Impedance V+ = 2V — 1 — MΩ

V+ = 5V — 100 — kΩ

NOTES:

1. Connecting any terminal to voltages greater than V+ 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 TC7662B.

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

3. In the test circuit, there is no external capacitor applied to pin 7. However, when the device is plugged into a test socket, there is usually a very
small but finite stray capacitance present, of the order of 5pF.

4. The TC7662B can operate without an external diode over the full temperature and voltage range. This device will function in existing designs which
incorporate an external diode with no degradation in overall circuit performance.

4-84

TELCOM SEMICONDUCTOR, INC.

V

IN

S

3

S

1

S

2

S

4

C

2

V

OUT

= – V

IN

C

1

CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER

1

TC7662B

DETAILED DESCRIPTION

The TC7662B contains all the necessary circuitry to
complete a negative voltage converter, with the exception of
two external capacitors which may be inexpensive 1µF
polarized electrolytic types. The mode of operation of the
device may be best understood by considering Figure 2,
which shows an idealized negative voltage converter. Ca­pacitor C1 is charged to a voltage V+ for the half cycle when
switches S1 and S3 are closed. (Note: Switches S2 and S
are open during this half cycle.) During the second half cycle
of operation, switches S2 and S4 are closed, with S1 and S
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. The TC7662B approaches this ideal situation
more closely than existing non-mechanical circuits.

In the TC7662B, the four switches of Figure 2 are MOS
power switches; S1 is a P-channel device and S2, S3 and S
are N-channel devices. The main difficulty with this ap­proach is that in integrating the switches, the substrates of
S3 and S4 must always remain reverse biased with respect
to their sources, but not so much as to degrade their “ON”
resistances. In addition, at circuit start up, and under output
short circuit conditions (V
be sensed and the substrate bias adjusted accordingly.
Failure to accomplish this would result in high power losses
and probable device latchup.

The problem is eliminated in the TC7662B by a logic
network which senses the output voltage (V
with the level translators, and switches the substrates of S
and S4 to the correct level to maintain necessary reverse
bias.

The voltage regulator portion of the TC7662B is an
integral part of the anti-latchup circuitry; however, its inher­ent voltage drop can degrade operation at low voltages.
Therefore, to improve low voltage operation, the “LV” pin
should be connected to GND, disabling the regulator. For
supply voltages greater than 3.5 volts, the LV terminal must
be left open to insure latchup proof operation and prevent
device damage.

= V+), the output voltage must

OUT

) together

OUT

THEORETICAL POWER EFFICIENCY
CONSIDERATIONS

In theory, a voltage converter can approach 100%

efficiency if certain conditions are met:
A. The drive circuitry consumes minimal power.
B. The output switches have extremely low ON resistance

and virtually no offset.

C. The impedances of the pump and reservoir capacitors

4

are negligible at the pump frequency.

3

The TC7662B approaches these conditions for nega-

tive voltage conversion 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

4

where V1 and V2 are the voltages on C1 during the pump and

1

– V

2

)

2

transfer cycles. If the impedances of C1 and C2 are relatively
high at the pump frequency (refer to Figure 2) compared to
the value of RL, there will be a substantial difference in
voltages V1 and V2. Therefore, it is desirable not only 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.

Dos and Don’ts

1. Do not exceed maximum supply voltages.

3

2. Do not connect the LV terminal to GND for supply
voltages greater than 3.5 volts.

3. Do not short circuit the output to V+ supply for voltages
above 5.5 volts for extended periods; however,
transient conditions including start-up are okay.

2

3

4

5

6

+

NOTE: For large values of C

V

1
2

+

C

1

10 µF

and C2 should be increased to 100 µF.

of C

1

TC7662B

3
4

(>1000 pF), the values

OSC

Figure 1. TC7662B Test Circuit

8
7
6
5

TELCOM SEMICONDUCTOR, INC.

I

S

+

V

(+5V)

I

L

R

L

V

O

C

2

10 µF

+

Figure 2. Idealized Negative Voltage Capacitor

7

8

4-85

TC7662B

CHARGE PUMP DC-TO-DC

VOLTAGE CONVERTER

4. When using polarized capacitors in the inverting mode,
the + terminal of C1 must be connected to pin 2 of the
TC7662B and the – terminal of C2 must be connected
to GND.

5. If the voltage supply driving the TC7662B has a large
source impedance (25-30 ohms), then a 2.2µF capaci­tor from pin 8 to ground may be required to limit the
rate of rise of the input voltage to less than 2V/µsec.

TYPICAL APPLICATIONS
Simple Negative Voltage Converter

The majority of applications will undoubtedly utilize the
TC7662B for generation of negative supply voltages. Figure
3 shows typical connections to provide a negative supply
where a positive supply of +1.5V to +15V is available. Keep
in mind that pin 6 (LV) is tied to the supply negative (GND)
for supply voltages below 3.5 volts.

V+

1

10 µF

2

+
–

Figure 3. Simple Negative Converter and its Output Equivalent

3
4

TC7662B

a.

The output characteristics of the circuit in Figure 3 can
be approximated by an ideal voltage source in series with a
resistance as shown in Figure 3b. The voltage source has a
value of–(V+). The output impedance (RO) is a function of
the ON resistance of the internal MOS switches (shown in
Figure 2), the switching frequency, the value of C1 and C2,
and the ESR (equivalent series resistance) of C1 and C2. A
good first order approximation for RO is:

8
7
6
5

10 µF

R

O

V

V

= –V+

–
+

OUT

–

V+

+

OUT

b.

voltage and temperature (See the Output Source Resis­tance graphs), typically 23Ω at +25°C and 5V. Careful
selection of C1 and C2 will reduce the remaining terms,
minimizing the output impedance. High value capacitors will
reduce the 1/(f

x C1) component, and low ESR capaci-

PUMP

tors will lower the ESR term. Increasing the oscillator fre­quency will reduce the 1/(f

x C1) term, but may have the

PUMP

side effect of a net increase in output impedance when C1 >
10µF and there is not enough time to fully charge the
capacitors every cycle. In a typical application when f

OSC

=

10kHz and C = C1 = C2 = 10µF:
RO ≅ 2 x 23 + + 4 x ESRC1 + ESR

(5 x 103 x 10 x 10-6)

1

C2

RO ≅ (46 + 20 + 5 x ESRC) Ω

Since the ESRs of the capacitors are reflected in the
output impedance multiplied by a factor of 5, a high value
could potentially swamp out a low 1/(f

x C1) term,

PUMP

rendering an increase in switching frequency or filter capaci­tance ineffective. Typical electrolytic capacitors may have
ESRs as high as 10Ω.

Output Ripple

ESR also affects the ripple voltage seen at the output.
The total ripple is determined by 2 voltages, A and B, as
shown in Figure 4. Segment A is the voltage drop across the
ESR of C2 at the instant it goes from being charged by C
(current flowing into C2) to being discharged through the
load (current flowing out of C2). The magnitude of this
current change is 2 x I
ESRC2 volts. Segment B is the voltage change across C
during time t2, the half of the cycle when C2 supplies current
to the load. The drop at B is I
peak ripple voltage is the sum of these voltage drops:

V

≅ ( + ESR

RIPPLE

2 x f

, hence the total drop is 2 x I

OUT

x t2/C2 volts. The peak-to-

OUT

1

PUMP

x C

2

C2

x I

OUT

OUT

)

1

x

2

RO ≅ 2(R

(f

= , R

PUMP

Combining the four R

RO ≅ 2 x RSW + + 4 x ESRC1 + ESRC2Ω

+ R

SW1

ESRC1) + + ESR

f

OSC

2

+ ESRC1) + 2(R

SW3

1

f

x C

PUMP

SWX

terms as RSW, we see that:

SWX

1

f

x C

PUMP

1

= MOSFET switch resistance)

1

SW2

+ R

C2

RSW, the total switch resistance, is a function of supply

4-86

SW4

+

0

V

– (V+)

t

2

B

A

Figure 4. Output Ripple

t

1

TELCOM SEMICONDUCTOR, INC.

1
2
3
4

8
7
6
5

TC7662B

+

V

+

+

CMOS
GATE

10µF

V

OUT

10µF

1 kΩ

V

+

CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER

1

TC7662B

Paralleling Devices

Any number of TC7662B voltage converters may be
paralleled to reduce output resistance (Figure 5). 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 TC7662B)

R

=

OUT

1
2

C

1

3
4

TC7662B

"1"

Figure 5. Paralleling Devices

OUT

n (number of devices)

+

V

8
7
6
5

C

1
2
3

1

4

TC7662B

"n"

8
7
6
5

R

L

C

2

+

Cascading Devices

The TC7662B may be cascaded as shown to produce
larger negative multiplication of the initial supply voltage.
However, due to the finite efficiency of each device, the
practical limit is 10 devices for light loads. The output voltage
is defined by:

V

= –n(VIN)

OUT

Changing the TC7662B Oscillator Frequency

It may be desirable in some applications (due to noise or
other considerations) to increase the oscillator frequency.
This is achieved by one of several methods described
below:

By connecting the BOOST Pin (Pin 1) to V+, the oscilla­tor charge and discharge current is increased and, hence
the oscillator frequency is increased by approximately 3-1/
2 times. The result is a decrease in the output impedance
and ripple. This is of major importance for surface mount
applications where capacitor size and cost are critical.
Smaller capacitors, e.g., 0.1µF, can be used in conjunction
with the Boost Pin in order to achieve similar output currents
compared to the device free running with C1 = C2 = 1µF or
10µF. (Refer to graph of Output Source Resistance as a
Function of Oscillator Frequency).

Increasing the oscillator frequency can also be achieved
by overdriving the oscillator from an external clock as shown
in Figure 7. In order to prevent device latchup, 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-up­resistor 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.

2

3

4

5

where n is an integer representing the number of devices
cascaded. The resulting output resistance would be ap­proximately the weighted sum of the individual TC7662B
R

values.

OUT

+

V

1
2

+

TC7662B

10µF

3
4

*V

= –nV

OUT

Figure 6. Cascading Devices for Increased Output Voltage

TELCOM SEMICONDUCTOR, INC.

8
7
6
5

"1"

+

10µF

+

10µF

1
2
3
4

TC7662B

"n"

8
7
6
5

+

10µF

V

OUT

Figure 7. External Clocking

It is also possible to increase the conversion efficiency
of the TC7662B at low load levels by lowering the oscillator
frequency. This reduces the switching losses, and is shown
in Figure 8. However, lowering the oscillator frequency will
cause an undesirable increase in the impedance of the
pump (C1) and reservoir (C2) capacitors; this is overcome by
increasing the values of C1 and C2 by the same factor that
the frequency has been reduced. For example, the addition
of a 100pF capacitor between pin 7 (Osc) and V+ will lower
the oscillator frequency to 1kHz from its nominal frequency
of 10kHz (multiple of 10), and thereby necessitate a corre­sponding increase in the value of C1 and C2 (from 10µF to
100µF).

4-87

6

7

8

TC7662B

CHARGE PUMP DC-TO-DC

VOLTAGE CONVERTER

+

V

1
2

+

C

1

TC7662B

3
4

Figure 8. Lowering Oscillator Frequency

8
7
6
5

C

OSC

V

OUT

C

2

+

Positive Voltage Doubling

The TC7662B may be employed to achieve positive
voltage doubling using the circuit shown in Figure 9. In this
application, the pump inverter switches of the TC7662B are
used to charge C1 to a voltage level of V+ – VF (where V+ is
the supply voltage and VF is the forward voltage on C1 plus
the supply voltage (V+) 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
on the output current, but for V+ = 5V and an output current
of 10 mA, it will be approximately 60Ω.

+

V

) will depend

OUT

+

V

1
2

TC7662B

3
4

+

C

1

Figure 10. Combined Negative Converter and Positive Doubler

8
7
6
5

+

C

2

D

D

V
–(V+–VF)

+

1

V

OUT

(2 V+) – (2 VF)

2

+

OUT

C

3

=

C

4

=

Voltage Splitting

The bidirectional characteristics can also be used to
split a higher supply in half, as shown in Figure 11. The
combined load will be evenly shared between the two sides
and a high value resistor to the LV pin ensures start-up.
Because the switches share the load in parallel, the output
impedance is much lower than in the standard circuits, and
higher currents can be drawn from the device. By using this
circuit, and then the circuit of Figure 6, +15V can be
converted (via +7.5V and –7.5V) to a nominal –15V, though
with rather high series resistance (~250Ω).

1
2

TC7662B

3
4

Figure 9. Positive Voltage Multiplier

8

D

7
6
5

1

+

C

1

D

2

V

OUT

(2 V+) – (2 VF)

+

C

2

=

Combined Negative Voltage Conversion
and Positive Supply Multiplication

Figure 10 combines the functions shown in Figures 3
and 9 to provide negative voltage conversion and positive
voltage doubling 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 doubled
positive voltage. There is a penalty in this configuration
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.

+

V

R

L1

V

=

OUT

–

V+–V

R

3

2

50

2

µF

L2

Figure 11. Splitting a Supply in Half

50 µF

+

-

50
µF

+

-

+

-

1
2
3
4

TC7662B

8
7
6
5

–

V

4-88

TELCOM SEMICONDUCTOR, INC.

CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER

Regulated Negative Voltage Supply

In some cases, the output impedance of the TC7662B
can be a problem, particularly if the load current varies
substantially. The circuit of Figure 12 can be used to over­come this by controlling the input voltage, via an ICL7611
low-power CMOS op amp, in such a way as to maintain a
nearly constant output voltage. Direct feedback is advisable,
since the TC7662B’s output does not respond instanta­neously to change in input, but only after the switching delay.
The circuit shown supplies enough delay to accommodate
the TC7662B, while maintaining adequate feedback. An
increase in pump and storage capacitors is desirable, and
the values shown provide an output impedance of less than
5Ω to a load of 10mA.

TTL DATA

INPUT

1µF

1

TC7662B

+5 LOGIC SUPPLY

2

11

12

+5V

-5V

1

RS232

3

DATA
OUTPUT

3

16

4

1
2

+
–

3
4

TC7662B

15

8
7
6
5

1µF

IH5142

13 14

+

56k

+8V

50k

100k

50k

+8V

–

+

100µF

800k

Figure 12. Regulating the Output Voltage

1
2

+

-

3
4

TC7662B

250K

VOLTAGE

ADJUST

–

10µF

+

V+

8
7
6
5

V

OUT

Figure 13. RS232 Levels from a Single 5V Supply

4

5

100µF

6

TELCOM SEMICONDUCTOR, INC.

7

8

4-89

TC7662B

TYPICAL CHARACTERISTICS

Supply Current vs. Temperature

(with Boost Pin = V

1000

IN

CHARGE PUMP DC-TO-DC

VOLTAGE CONVERTER

)

101.0

Voltage Conversion

800

600

(µA)

DD

400

I

200

0

-40 -20 0 20 40 10060 80

TEMPERATURE (°C)

VIN = 12V

VIN = 5V

Output Source Resistance vs. Supply Voltage

100

70
50

30

100.5
Without Load

100.0

99.5

99.0

10K Load

98.5

VOLTAGE CONVERSION EFFICIENCY (%)

98.0
112111098756423

INPUT VOLTAGE VIN (V)

TA = 25°C

Output Source Resistance vs. Temperature

100

80

60

40

VIN = 2.5V

VIN = 5.5V

OUTPUT SOURCE RESISTANCE (Ω)

10

1.5 1211.510.59.58.57.55.5 6.54.52.5 3.5

Output Voltage vs. Output Current

0

-2

(V)

-4

OUT

-6

-8

-10

OUTPUT VOLTAGE V

-12
0 1009080706040 503010 20

4-90

SUPPLY VOLTAGE (V)

OUTPUT CURRENT (mA)

I

OUT

= 20mA

T

= 25°C

A

20

OUTPUT SOURCE RESISTANCE (Ω)

0

-40 -20 0 20 40 10060 80

TEMPERATURE (°C)

Supply Current vs. Temperature

200
175
150

(µA)

DD

125
100

75
50

SUPPLY CURRENT I

25

0

-40 -20 0 20 40 10060 80

TEMPERATURE (°C)

TELCOM SEMICONDUCTOR, INC.

VIN = 12.5V

VIN = 5.5V

CHARGE PUMP DC-TO-DC
VOLTAGE CONVERTER

TYPICAL CHARACTERISTICS (Cont.)

1

TC7662B

Unloaded Osc Freq vs. Temperature

12

10

8

6

4

2

OSCILLATOR FREQUENCY (kHz)

0

-40 -20 0 20 40 10060 80

TEMPERATURE (°C)

VIN = 5V

VIN = 12V

Unloaded Osc Freq vs. Temperature

60

50

40

30

20

10

OSCILLATOR FREQUENCY (kHz)

0

-40 -20 0 20 40 10060 80

with Boost Pin = V

VIN = 12V

TEMPERATURE (°C)

2

IN

VIN = 5V

3

4

5

6

7

TELCOM SEMICONDUCTOR, INC.

8

4-91