Datasheet

ManualsBrandsLinear Technology ManualsDC / DC Inductorless Adjustable Charge PumpsSwitched-Capacitor Wide Input Range Voltage Converter with Shutdown Step-Down 50mA NSOIC-

LTC114 4

1144fa

For more information www.linear.com/LTC1144

Typical applicaTion

FeaTures DescripTion

Switched-Capacitor

Wide Input Range

Voltage Converter

with Shutdown

The LT C

1144 is a monolithic CMOS switched-capacitor

voltage converter. It performs supply voltage conversion

from positive to negative from an input range of 2V to

18V, resulting in complementary output voltages of –2V to

–18V. Only two noncritical external capacitors are needed

for the charge pump and charge reservoir functions.

The converter has an internal oscillator that can be

overdriven by an external clock or slowed down when

connected to a capacitor. The oscillator runs at a 10kHz

frequency when unloaded. A higher frequency outside the

audio band can also be obtained if the Boost Pin is tied to

. The SHDN pin reduces supply current to 8µA and can

be used to save power when the converter is not in use.

The LTC1144 contains an internal oscillator, divide-by- two,

voltage level shifter, and four power MOSFETs. A special

logic circuit will prevent the power N-channel switch

substrate from turning on.

applicaTions

Wide Operating Supply Voltage Range: 2V to 18V

Boost Pin (Pin 1) for Higher Switching Frequency

Simple Conversion of 15V to –15V Supply

Low Output Resistance: 120Ω Maximum

Power Shutdown to 8µA with SHDN Pin

Open Circuit Voltage Conversion Efficiency:

99.9% Typical

Power Conversion Efficiency: 93% Typical

Easy to Use

Conversion of 15V to ±15V Supplies

Inexpensive Negative Supplies

Data Acquisition Systems

High Voltage Upgrade to LTC1044 or 7660

Voltage Division and Multiplications

Automotive Applications

Battery Systems with Wall Adapter/Charger

L, LT , LT C, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

Output Voltage vs Load Current, V

= 15VGenerating –15V from 15V

BOOST

CAP

GND

CAP

–

OSC

SHDN

OUT

10µF

–

15V OUTPUT

15V INPUT

LTC1144

10µF

1144 TA01

LOAD CURRENT (mA)

0 10

OUTPUT VOLTAGE (V)

–15

–14

–13

–12

–11

–10

1144 TA02

OUT

= 56Ω

= 25°C

Downloaded from Arrow.com.

Summary of content (12 pages)

PAGE 1
LTC1144 Switched-Capacitor Wide Input Range Voltage Converter with Shutdown Features n n n n n n n n Description Wide Operating Supply Voltage Range: 2V to 18V Boost Pin (Pin 1) for Higher Switching Frequency Simple Conversion of 15V to –15V Supply Low Output Resistance: 120Ω Maximum Power Shutdown to 8µA with SHDN Pin Open Circuit Voltage Conversion Efficiency: 99.
PAGE 2
LTC1144 Absolute Maximum Ratings (Note 1) Supply Voltage (V+) (Transient) ................................20V Supply Voltage (V+) (Operating) ............................... 18V Input Voltage on Pins 1, 6, 7 (Note 2) ............................. –0.3V < VIN < (V+) + 0.3V Output Short-Circuit Duration V+ ≤ 10V ..................................................... Indefinite V+ ≤ 15V .......................................................... 30 sec V+ ≤ 20V ..............................................
PAGE 3
LTC1144 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range,V+ = 15V, COSC = 0pF, Test Circuit Figure 1, otherwise specifications are at TA = 25°C.
PAGE 4
LTC1144 Typical Performance Characteristics Output Resistance vs Supply Voltage 300 Output Resistance vs Temperature 200 150 100 V + = 5V IL = 3mA 100 80 60 V + = 15V IL = 20mA 40 50 6 10 12 14 8 SUPPLY VOLTAGE (V) 16 20 –55 –25 18 50 25 75 0 TEMPERATURE (°C) Oscillator Frequency as a Function of COSC OSCILLATOR FREQUENCY (kHz) OSCILLATOR FREQUENCY (kHz) 1000 100 BOOST = V + 10 1 BOOST = OPEN OR GROUND 0.
PAGE 5
LTC1144 Typical Performance Characteristics Power Conversion Efficiency vs Oscillator Frequency 30 60 IS 20 4 20 TA = 25°C V + = 5V C1 = C2 = 10µF BOOST = OPEN (SEE TEST CIRCUIT) 12 16 8 LOAD CURRENT (mA) 20 10 95 100µF 10µF 90 85 IL = 3mA 1µF 80 75 0.1 –1 1µF 0.1µF 0.1µF 10µF 500 1µF 1µF 100µF IL = 20mA 1 10 OSCILLATOR FREQUENCY (kHz) 0 0.1 100 1 10 OSCILLATOR FREQUENCY (kHz) Output Voltage vs Load Current 0 V + = 5V TA = 25°C C1 = C2 BOOST = 5V BOOST = OPEN –2 0.1µF 10µF 0.
PAGE 6
LTC1144 Test Circuit V+ 15V 1 2 C1 + 3 10µF IS 8 EXTERNAL OSCILLATOR R L 7 LTC1144 4 6 IL 5 COSC C2 10µF VOUT + 1144 F01 Figure 1. Applications Information Theory of Operation To understand the theory of operation of the LTC1144, 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.
PAGE 7
LTC1144 Applications Information theory will explain how the LTC1144 behaves. The loss, and hence the efficiency, is set by the output impedance. As frequency is decreased, the output impedance will eventually be dominated by the 1/(f × C1) term and power efficiency will drop. V+ 9I BOOST (1) Note also that power efficiency decreases as frequency goes up. This is caused by internal switching losses which occur due to some finite charge being lost on each switching cycle.
PAGE 8
LTC1144 Typical Applications Negative Voltage Converter V IN 2V TO 18V Figure 8 shows a typical connection which will provide a negative supply from an available positive supply. This circuit operates over full temperature and power supply ranges without the need of any external diodes. The output voltage (pin 5) characteristics of the circuit are those of a nearly ideal voltage source in series with a 56Ω resistor.
PAGE 9
LTC1144 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. N Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510 Rev I) .400* (10.160) MAX 8 7 6 5 1 2 3 4 .255 ±.015* (6.477 ±0.381) .300 – .325 (7.620 – 8.255) .008 – .015 (0.203 – 0.381) ( +.035 .325 –.015 8.255 +0.889 –0.381 ) .045 – .065 (1.143 – 1.651) .065 (1.651) TYP .100 (2.54) BSC .130 ±.005 (3.302 ±0.127) .120 (3.048) .020 MIN (0.508) MIN .
PAGE 10
LTC1144 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610 Rev G) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 .010 – .020 × 45° (0.254 – 0.508) 2 .053 – .069 (1.346 – 1.752) 0°– 8° TYP .016 – .050 (0.406 – 1.270) 5 .150 – .157 (3.810 – 3.988) NOTE 3 1 RECOMMENDED SOLDER PAD LAYOUT .008 – .010 (0.
PAGE 11
LTC1144 Revision History REV DATE DESCRIPTION A 04/14 Change 0.0002% to 0.002% under the Ultra-Precision Voltage Divider section. PAGE NUMBER 8 1144fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. For more information www.linear.
PAGE 12
LTC1144 Typical Application Regulated –5V Output Voltage 9V 1 Figure 12 shows a regulated –5V output with a 9V input. With a 0mA to 5mA load current, the ROUT is below 20Ω. 1µF 8 2 + 3 7 LTC1144 6 4 Paralleling for Lower Output Resistance Additional flexibility of the LTC1144 is shown in Figure 13. Two LTC1144s are connected in parallel to provide a lower effective output resistance.