Datasheet SP682 Datasheet (Sipex)

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Page 1

Corporation

SP682

Micro Power Inverting Charge Pump

■ Low Power Voltage Conversion

■ +2.4V to +5.5V Input Range

■ 99% Voltage Conversion Efficiency

■ Typical 60µA Supply Current

C1-

C2+

C2-

OUT

2 3 4

SP682

8 Pin MSOP

C1+ V

GND

■ Requires Only Three External Capacitors

■ Includes Low Power Shutdown Option

Now Available in Lead Free Packaging

■ Ideal in Portable Applications Such As Handheld Instruments Cellular Phones Personal Digital Assistants Laptops and Notebooks

■ Pin Compatible Upgrade to Microchip's TC682

APPLICATIONS

■ LCD Display

■ Negative bias supply for op amps

■ Serial interface protocol circuits

DESCRIPTION

The SP682 is a monolithic charge pump voltage converter that produces a doubled, negative voltage from a single positive supply. The SP682 charge pump outputs a –10V voltage from a +5V input. Three external charge pump capacitors are required to support the voltage conversion and voltage doubling process. An internal oscillator generates a 12kHz clock which cycles the internal switching that charges the storage and transfer capacitors. The charge pump architecture is fabricated using a low power BiCMOS process technology.

The SP682 charge pump is ideal for low power applications requiring a typical +3V battery source such as a lithium cell. Typical applications are handheld instruments, notebook and laptop computers, cellular phones, and data acquisition or GP systems. The SP682 is packaged in either 8-pin NSOIC, 8-pin MSOP for surface mount applications, and 8 Pin PDIP.

+2.4V to +5V

TYPICAL APPLICATION CIRCUIT

1µF

C1+

C1–

C2+

C2–

SP682

GND

OUT

Page 2

ABSOLUTE MAXIMUM RATINGS

These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

VCC...........................................................................+7V

........................................................................–11V

OUT

Storage Temperature..........................-65˚C to +150˚C

Power Dissipation:

8-pin NSOIC......................................500mW

8-pin MSOP......................................320mW

8-pin PDIP......................................750mW

Package Derating: 8-pin NSOIC:

..................................................128 °C/W

ø 8-pin MSOP:

øJA..................................................216°C/W

8-pin PDIP:

..................................................97°C/W

ELECTRICAL CHARACTERISTICS

TA = T

to T

and VCC = +5V. Charge pump cap = 3.3µF, unless otherwise noted.

MIN

MAX

SUPPLY CURRENT CHARGE PUMP CAPACITORS: 3.3µF

in shutdown 1 µATA = +25OC, SD = +5V

CHARGE PUMP OUTPUT CHARGE PUMP CAPACITORS: 3.3µF

OUT

SOURCE RESISTANCE

OUT

OSCILLATOR FREQUENCY

OSC

MIN. TYP. MAX. UNITS CONDITIONS

60 120 µARL = ∞, TA = +25°C

200 µARL = ∞

–9.9 –9.99 Volts RL = ∞ –9.0 –9.5 Volts RL = 2kΩ

140 180 Ω IL = 10mA, TA = +25°C

230 Ω IL = 10mA

380 450 Ω IL = 5mA, VCC = +2.8V

12 20 kHz f

= 2 X f

osc

C1+

CONVERSION EFFICIENCY

OUT EFF

99 99.9 % RL = ∞ 90 95 % RL = 2kΩ

START-UP TIMING

Power On Delay 12 ms RL = 2kΩ

OUT

SHUTDOWN TIMING

Shutdown to V

Delay 5 ms RL = 2kΩ

OUT

SUPPLY VOLTAGE

Operating Temperature Range

- C 0 +70

- E -40 +85

+2.4 +5.5 Volts

o o

C C

Page 3

THEORY OF OPERATION

The SP682's charge pump design is a simplified version of Sipex's original patented charge pump design (5,306,954) except that it only generates a negative output. The charge pump utilizes external capacitors to store the charge. Figure 1 shows the waveform found on the negative side of capacitor C2. There is a free– running oscillator, running at 12kHz, that controls the two phases of the voltage shifting. A description of each phase follows.

Phase 1

charge storage — During this phase of

OUT

the clock cycle, the positive side of capacitors C1 and C2 are initially charged to +5V. C then switched to ground and the charge on C is transferred to C +5V, the voltage potential across capacitor C

–

. Since C

is connected to

is now 10V.

Phase 2

transfer — Phase two of the clock con-

OUT

nects the negative terminal of C2 to the V storage capacitor and the positive terminal of

OUT

C2 to ground, and transfers the generated –l0V to C3. Simultaneously, the positive side of capacitor C 1 is switched to +5V and the negative side is connected to ground.

The oscillator frequency or clock rate for the charge pump is designed for low power operation. The oscillator operates at a frequency of

about 12kHz (20kHz maximum) which conserves power as opposed to higher frequency which operation typically draws more power from VCC. The external charge pump capacitors specified are 3.3µF but the absolute minimum should be 1µF.

EFFICIENCY INFORMATION

A charge pump theoretically produces a doubled voltage at 100% efficiency. However in the real world, there is a small voltage drop on the output which reduces the output efficiency. The SP682 can usually run 99.9% efficient without driving a load. While driving a 1kΩ load, the SP682 remains over 90% efficiency.

–

Output Voltage Efficiency = V

= –2*VCC + V

OUT

= (I

OUT

)*(R

OUT

*(V

DROP

Power Loss = I

OUT

DROP

)

DROP

The efficiency changes as the external charge pump capacitors are varied. Larger capacitor values will strengthen the output and reduce output ripple. Although smaller capacitors will cost less and save board space, lower values will reduce the output drive capability and also increase the output ripple.

VCC = +5V

–5V

+5V

––

–5V

/ (–2*VCC);

)

Storage Capacitor

OUT

–

Figure 2. Charge Pump Phase 1

VCC = +5V

Figure 1. Charge Pump Waveform

Figure 3. Charge Pump Phase 2

––

–10V

Storage Capacitor

OUT

–

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THEORY OF OPERATION

The ESR of the charge pump capacitors also determine the output resistance. Assuming that switch resistances are approximately equal, the output resistance can be derived as shown below:

= 16*(R

OUT

+ 1 / (f

is typically 140Ω at +25°C with VCC at

OUT

+5V using 3.3µF capacitors. The total internal

) + 4*( ESRC1+ ESRC2) + ESR

SW1-4

* C1) + 1 / (f

OSC

* C2)

switch resistance (16*RSW) is approximately 90Ω. The table below shows the comparison of R

versus C1&C2.

OUT

C1, C2 (µF) ROUT (Ω)

0.05 4085

0.10 2084

0.47 510

1.00 285

3.30 140

4.70 125

10.00 105

22.00 94

Table 1. R

.vs. C1, C2

OUT

The output voltage ripple is also affected by the capacitors, specifically C will reduce the output ripple for a given output

. Larger values

OUT

current load of current. The formula representation is:

SHUTDOWN FEATURE

The SP682 charge pump includes a shutdown feature (pin 8) which disables the charge pump when the V activate the shutdown mode. If shutdown is not

is not needed. A logic "1" will

OUT

needed, it can be left open where an internal pull-down resistor will always keep the charge pump active. Typical input current for the shutdown pin is 3µA. The shutdown feature is another option for conserving power in portable applications, reducing current to only 1µA.

PARALLEL DEVICES

Multiple SP682 charge pumps can be connected in parallel. However, the effective output resistance now is the output resistance of a single device divided by the number of devices. Connecting multiple pumps allows the user to save on the storage capacitor. The charge pump capacitors still must be separate for each device.

APPLICATIONS INFORMATION

The SP682 charge pump produces a doubled, inverted voltage from the VCC input. As such, it can serve in many applications where a negative –5V to –10V output is needed. Typical applications include powering analog switches, and biasing LCD displays and panels.

= {1 / [2 * (f

RIPPLE

To minimize the output ripple, the C capacitor can be increased to over 10µF whereas

* C3)] + 2 * (ESRC3)} * I

OSC

OUT

storage

the pump capacitors can range from 1µF to 5µF. Table 2 shows the typical V C

values.

OUT

(µF) V

OUT

0.50 1020

1.00 520

3.30 172

4.70 120

10.00 70

22.00 43

Table 2. C3 .vs. V

RIPPLE

for given

(mV)

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E/2

PACKAGE: 8 PIN NSOIC

INDEX AREA (D/2 X E1/2)

TOP VIEW

8 Pin NSOIC JEDEC MO-012 (AA) Variation

SYMBOL

MIN NOM MAX

A1.35-1.75 A1 0.1 - 0.25 A2 1.25 - 1.65

b0.31-0.51

c0.17-0.24

E E1

4.90 BSC

6.00 BSC

3.90 BSC

1.27 BSC

L0.4-1.27 L1 L2

1.04 REF

0.25 BSC

ø0º-8º ø1 5º - 15º

Note: Dimensions in (mm)

E1/2

Seating Plane

Ø1

VIEW C

SIDE VIEW

SEE VIEW C

Gauge Plane

Seating Plane

BASE METAL

SECTION B-B

WITH PLATING

Page 6

E/2

PACKAGE: 8 PIN MSOP

D e1

Ø1

Seating Plane

Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2)

8 Pin MSOP JEDEC MO-187 (AA) Variation

SYMBOL

MIN NOM MAX

A--1.1 A1 0 - 0.15 A2 0.75 0.85 0.95

b 0.22 - 0.38

c 0.08 - 0.23

E E1

e e1

3.00 BSC

4.90 BSC

3.00 BSC

0.65 BSC

1.95 BSC

L 0.4 0.6 0.8 L1 L2

0.95 REF

0.25 BSC N-8R 0.07 - -

R1 0.07 - -

ø0º-8º

ø1 0º - 15º

Note: Dimensions in (mm)

WITH PLATING

BASE METAL

Gauge Plane

Ø1

Section B-B

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PACKAGE: 8 PIN PDIP

INDEX AREA

N/2

8 PIN PDIP JEDEC MS-001 (BA) Variation

SYMBOL MIN NOM MAX

A--0.21 A1 0.15 - A2 0.115 0.13 0.195

b 0.014 0.018 0.022 b2 0.045 0.06 0.07 b3 0.3 0.039 0.045

c 0.008 0.01 0.014

D 0.355 0.365 0.4 D1 0.005 - -

E 0.3 0.31 0.325 E1 0.24 0.25 0.28

e eA

.100 BSC .300 BSC

eB - - 0.43

L 0.115 0.13 0.15

Note: Dimensions in (mm)

Page 8

ORDERING IFORMATION

Part Number Temperature Range Package Types

SP682CN............................................. -0°C to +70°C ................................................................. 8-pin NSOIC

SP682CN/TR....................................... -0°C to +70°C .................................................................8-pin NSOIC

SP682CP............................................. -0°C to +70°C .................................................................... 8-pin PDIP

SP682CU............................................. -0°C to +70°C .................................................................. 8-pin MSOP

SP682CU/TR....................................... -0°C to +70°C ..................................................................8-pin MSOP

SP682EN........................................... -40°C to +85°C ................................................................. 8-pin NSOIC

SP682EN/TR ..................................... -40°C to +85°C ................................................................. 8-pin NSOIC

SP682EP ........................................... -40°C to +85°C .................................................................... 8-pin PDIP

SP682EU........................................... -40°C to +85°C .................................................................. 8-pin MSOP

SP682EU/TR ..................................... -40°C to +85°C ..................................................................8-pin MSOP

/TR = Tape and Reel Pack quantity is 2,500 for NSOIC and MSOP.

CLICK HERE TO ORDER SAMPLES

Corporation

ANALOG EXCELLENCE

Sipex Corporation Headquarters and

Sales Office

233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600

Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.