Linear Technology LTC1046MJ8, LTC1046IN8, LTC1046, LTC1046CS8, LTC1046CN8 Datasheet

FEATURES

■

50mA Output Current

■

Plug-In Compatible with ICL7660/LTC1044

■

R

= 35Ω Maximum

OUT

■

300µA Maximum No Load Supply Current at 5V

■

Boost Pin (Pin 1) for Higher Switching Frequency

■

97% Minimum Open-Circuit Voltage Conversion
Efficiency

■

95% Minimum Power Conversion Efficiency

■

Wide Operating Supply Voltage Range: 1.5V to 6V

■

Easy to Use

■

Low Cost

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APPLICATIO S

LTC1046

“Inductorless”

5V to –5V Converter

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DESCRIPTIO

The LTC®1046 is a 50mA monolithic CMOS switched
capacitor voltage converter. It plugs in for ICL7660/
LTC1044 in 5V applications where more output current is
needed. The device is optimized to provide high current
capability for input voltages of 6V or less. It trades off
operating voltage to get higher output current. The
LTC1046 provides several voltage conversion functions:
the input voltage can be inverted (V
(V

OUT =VIN/

2) or multiplied (V

OUT

Designed to be pin-for-pin and functionally compatible
with the ICL7660 and LTC1044, the LTC1046 provides 2.5
times the output drive capability.

, LTC and LT are registered trademarks of Linear Technology Corporation.

= –VIN), divided

OUT

= ±nVIN).

■

Conversion of 5V to ±5V Supplies

■

Precise Voltage Division, V

■

Supply Splitter, V

OUT

OUT

= ±VS/2

TYPICAL APPLICATIO

Generating –5V from 5V

LTC1046

10µF

1

BOOST

2

+

+

CAP

3

GND

4

–

CAP

V

OSC

OUT

8

+

V

7

6

LV

5

= VIN/2

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10µF

+

1046 TA01

5V INPUT

–5V INPUT

Output Voltage vs Load Current for V+ = 5V

–5

–4

ICL7660/LTC1044,

–3

–2

OUTPUT VOLTAGE (V)

–1

0

0

= 55Ω

R

OUT

R

10 20 30 40

LOAD CURRENT, IL (mA)

LTC1046,

= 27Ω

OUT

TA = 25°C

50

1046 TA02

1

LTC1046

1

2

3

4

8

7

6

5

TOP VIEW

V

+

OSC
LV
V

OUT

BOOST

CAP

+

GND

CAP

–

J8 PACKAGE

8-LEAD CERDIP

N8 PACKAGE
8-LEAD PDIP

S8 PACKAGE

8-LEAD PLASTIC SO

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NUMBER

A

S

(Note 1)

W

O

LUTEXI TIS

A

WUW

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ARB

G

Supply Voltage ....................................................... 6.5V

Input Voltage on Pins 1, 6 and 7

(Note 2) ............................ –0.3 < V

< (V+) +0.3V

IN

Current into Pin 6 .................................................. 20µA

Output Short Circuit Duration

(V+ ≤ 6V) ...............................................Continuous

Operating Temperature Range

LTC1046C .................................... 0°C ≤ TA ≤ 70°C

PACKAGE

/

O

RDER I FOR ATIO

ORDER PART

LTC1046CN8
LTC1046CS8
LTC1046IN8
LTC1046IS8
LTC1046MJ8

LTC1046I .................................–40°C ≤ TA ≤ 85°C

LTC1046M .................................... –55°C to 125°C

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

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

LECTRICAL C CHARA TERIST

E

temperature range, otherwise specifications are at TA = 25°C. V+ = 5V, C

SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

I

S

+

V

+

V
R

OUT

f

OSC

P

EFF

V

OUTEFF

I

OSC

Supply Current RL = ∞, Pins 1 and 7 No Connection 165 300 165 300 µA

= ∞, Pins 1 and 7 No Connection, 35 35 µA

R

L

V+ = 3V

Minimum Supply Voltage RL = 5kΩ ● 1.5 1.5 V

L

Maximum Supply Voltage RL = 5kΩ ● 66V

H

Output Resistance V+ = 5V, IL = 50mA (Note 3) 27 35 27 35 Ω

V+ = 2V, IL = 10mA ● 60 85 60 90 Ω

Oscillator Frequency V+ = 5V (Note 4) 20 30 20 30 kHz

V+ = 2V 4 5.5 4 5.5 kHz
Power Efficiency RL = 2.4kΩ 95 97 95 97 %
Voltage Conversion RL = ∞ 97 99.9 97 99.9 %

Efficiency
Oscillator Sink or Source V

Current Pin 1 = 0V ● 4.2 35 4.2 40 µA

= 0V or V

OSC

Pin 1 = V

ICS

+

+

The ● denotes the specifications which apply over the full operating

T

= 160°C, θJA = 100°C (J8)

JMAX

= 110°C, θJA = 130°C (N8)

T

JMAX

T

= 150°C, θJA = 150°C (S8)

JMAX

= 0pF, unless otherwise noted.

OSC

LTC1046C LTC1046I/M

● 27 45 27 50 Ω

● 15 45 15 50 µA

S8 PART MARKING

1046
1046I

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Note 1: Absolute Maximum Ratings are those values beyond which
the life of the device may be impaired.

Note 2: Connecting any input terminal to voltages greater than V
less than ground 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 LTC1046.

2

Note 3: R

+

or

Note 4: f
fixture capacitance loading. The 0pF frequency is correlated to this 100pF
test point, and is intended to simulate the capacitance at pin 7 when the
device is plugged into a test socket and no external capacitor is used.

is measured at TJ = 25°C immediately after power-on.

OUT

is tested with C

OSC

= 100pF to minimize the effects of test

OSC

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LPER

R

F

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ATYPICA

Output Resistance vs Output Resistance vs Output Resistance vs
Oscillator Frequency Supply Voltage Temperature

500

400

(Ω)

O

300

200

C1 = C2
= 100µF

100

OUTPUT RESISTANCE, R

C1 = C2
= 10µF

TA = 25°C

+

V

= 10mA

I

L

C1 = C2
= 1µF

= 5V

CCHARA TERIST

E

C

1000

TA = 25°C

= 3mA

I

L

(Ω)

O

100

C

OUTPUT RESISTANCE, R

OSC

= 0pF

ICS

(Using Test Circuit in Figure 1)

80

C1 = C2 = 10µF

70

60

V+ = 2V, C

C

= 100pF

OSC

50

40

30

OUTPUT RESISTANCE (Ω)

20

= 0pF

OSC

V+ = 5V, C

LTC1046

= 0pF

OSC

0

100

1k 10k 100k

OSCILLATOR FREQUENCY, f

OSC

(Hz)

1046 G01

10

134

0

2567

SUPPLY VOLTAGE, V+ (V)

1046 G02

10

–25 0 75

–55

AMBIENT TEMPERATURE (°C)

25 50 100 125

Power Conversion Efficiency vs Power Conversion Efficiency vs Power Conversion Efficiency vs
Load Current for V+ = 2V Load Current for V+ = 5V Oscillator Frequency

100

(%)

90

EFF

80
70
60
50
40
30
20
10

POWER CONVERSION EFFICIENCY, P

0

12 5

0

34 67

LOAD CURRENT, IL (mA)

P

EFF

I

S

TA = 25°C

+

= 2V

V
C1 = C2 = 10µF

= 8kHz

f

OSC

8910

1046 G04

100

10

(%)

9
8
7
6
5
4
3
2
1
0

90

EFF

80

SUPPLY CURRENT (mA)

70
60
50
40
30
20
10

POWER CONVERSION EFFICIENCY, P

0

10 20 50

0

P

EFF

I

S

TA = 25°C

+

= 5V

V
C1 = C2 = 10µF
f

OSC

30 40 60 70

LOAD CURRENT, IL (mA)

= 30kHz

100
90
80
70
60
50
40
30
20
10
0

1046 G05

100

(%)

98

EFF

SUPPLY CURRENT (mA)

POWER CONVERSION EFFICIENCY, P

A

96
94
92
90
88
86
84
82
80

C

100

1k 10k 100k 1M

OSCILLATOR FREQUENCY, f

B

E

D

A = 100µF, 1mA
B = 100µF, 15mA
C = 10µF, 1mA
D = 10µF, 15mA
E = 1µF, 1mA
F = 1µF, 15mA

Output Voltage vs Load Current Output Voltage vs Load Current Oscillator Frequency as a
for V+ = 2V for V+ = 5V Function of C

2.5
TA = 25°C

+

2.0

= 2V

V

= 8kHz

f

OSC

1.5

C1 = C2 = 10µF

1.0

0.5

0.0

–0.5
–1.0

OUTPUT VOLTAGE (V)

–1.5
–2.0
–2.5

2

0

4

LOAD CURRENT, IL (mA)

SLOPE = 52Ω

10 12 14 16 18 20

6

8

1046 G07

5

TA = 25°C

+

4

= 5V

V

= 30kHz

f

OSC

3

C1 = C2 = 10µF

2
1
0

–1
–2

OUTPUT VOLTAGE (V)

–3
–4
–5

0

10 20 30 40

LOAD CURRENT, IL (mA)

SLOPE = 27Ω

50 60 70 80 90 100

1046 G08

100

(kHz)

OSC

10

1

OSCILLATOR FREQUENCY, f

0.1
1

EXTERNAL CAPACITOR (PIN 7 TO GND), C

OSC

PIN 1 = V

PIN 1 = OPEN

10 100 10000

F

OSC

1000

1046 G03

V+ = 5V

= 25°C

T

A

C1 = C2

(Hz)

1046 G06

V+ = 5V

= 25°C

T

A

+

OSC

1046 G09

(pF)

3

LTC1046

LPER

100

(kHz)

OSC

UW

R

F

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ATYPICA

Oscillator Frequency as a Oscillator Frequency vs
Function of Supply Voltage Temperature

TA = 25°C

= 0pF

C

OSC

CCHARA TERIST

E

C

ICS

(Using Test Circuit in Figure 1)

40

38

(kHz)

OSC

36

V+ = 5V
C

OSC

= 0pF

10

OSCILLATOR FREQUENCY, f

1

0

1457

AMBIENT TEMPERATURE (°C)

TEST CIRCUIT

23 6

1046 G10

1

2

+

10µF

C1

3

4

LTC1046

BOOST
CAP
GND
CAP

34

32

30

28

OSCILLATOR FREQUENCY, f

26

–25 0 75

–55

V+ (5V)

8

+

V

V

OSC

OUT

7

6

LV

5

+

–

EXTERNAL
OSCILLATOR

C

OSC

R

L

25 50 100 125

AMBIENT TEMPERATURE (°C)

I

S

I

L

V

OUT

C2
10µF

+

1046 F01

1046 G11

Figure 1

PPLICATI

A

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O

S

I FOR ATIO

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Theory of Operation

To understand the theory of operation of the LTC1046, a
review of a basic switched capacitor building block is
helpful.

In Figure 2, when the switch is in the left position, capacitor
C1 will charge to voltage V1. The total charge on C1 will be
q1 = C1V1. The switch then moves to the right, discharg­ing C1 to voltage V2. After this discharge time, the charge
on C1 is q2 = C1V2. Note that charge has been transferred
from the source, V1, to the output, V2. The amount of
charge transferred is:

∆ q = q1 – q2 = C1(V1 – V2).

4

If the switch is cycled “f” times per second, the charge
transfer per unit time (i.e., current) is:

I = f • ∆q = f • C1(V1 – V2).

V2V1

f

R

C1

Figure 2. Switched Capacitor Building Block

L

C2

1046 F02