SC1517CSK-5.TRT - Semtech Corp.

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

FEATURESDESCRIPTION

The SC1517-5 is pin compatible with LTC1517-5. This

versatile charge pump produces a regulated 5V output

from an input voltage ranging from 2.7V to 5V. The

Extremely low operating current (typically 10µA w ith no

load) prolongs battery usage time.The small device

footprint and the the low external parts count (one

0.1µF flying capacitor and two small bypass capacitors

at VIN and VOUT) make the part ideally suited for

compact circuit design.

The SC1517-5 charge pump can be used for

applications that require up to 20mA (3V <

VIN < 5V) of

output current, while providing a regulated 5V output

voltage. During short circuit a current limit circuitry

provides protection, while the thermal shutdown

capability cycles VOUT to prevent device failure. The

SC1517-5 is available in a 5 lead SOT-23 package.

APPLICATIONS

= Ultra low power: ICC = 10µA typ

= Short circuit/Thermal protected

= 5V+ 4% Regulated output

= VIN Range: 2.7V to 5V

= Output current:

10mA (VIN > 2.7V)

20mA (VIN > 3V)

= No inductors

= Ultra small application circuit

= 800kHz switching frequency

= Surface mount packaging (5 pin SOT-23)

= Cellular telephones

= Battery-operated equipment

= Local power supplies

= Handheld instruments

= PCMCIA supplies

TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com

Device(1) Package Temp. Range (TA)

SC1517CSK-5 SOT-23-5 0° to +70°C

ORDERING INFORMATION

Notes:

(1) Only available in tape and reel packaging. (Suffix ‘.TR’ ).

CIN = = COUT

C1 =

TYPICAL APPLICATION SCHEMATIC

Note :

Ceramic capacitors used for improved performance, Low ESR Tantalum with ESR < 0.5 Ohms could also be used.

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

ABSOLUTE MAXIMUM RATINGS

Parameter Symbol Maximum Units

Input Supply Voltage Vin -0.3 to 6 V

Output Supply Voltage Vout -0.3 to 6 V

Power Dissipation Pd391 mW

Thermal Resistance ° JA 256 °C/W

Operating Junction

Temperature Range TA0 to +70 °C

Operating Junction

Temperature Range TJ0 to +125 °C

Storage Temperature Range TSTG -65 to +150 °C

Lead Temperature

(Soldering) 10 Sec TLEAD +300 °C

ELECTRICAL CHARACTERISTICS

Unless specified: VIN = 2.7V to 5V, C1 = 0.1µF, CIN = 3.3µF, COUT = 6.8µF, 0° to +70°C.

Parameter Symbol Conditions Min Typ Max Units

Operating Input Voltage VIN 2.7 5 V

Output Voltage VOUT 2.7V < VIN < 5V, IOUT < 10mA 4.8 5.0 5.2

3V <

VIN < 5V, IOUT < 20mA 4.8 5.0 5.2 V

Input Supply Current ICC 2.7V < VIN < 5V, IOUT = 0 10 15 µA

VOUT Ripple (pk-pk)(1)(2) VRVIN = 3V, IOUT = 20mA, COUT = 6.8µF 75 mVP-P

Oscillator Frequency(1)(2) fOSC 800 kHz

VOUT Turn-On Time(1)(2) tON VIN = 3V, IOUT = 0mA 1 ms

Soft start / Short circuit

Current limit(1)(2)(3) Ilimit Short circuit applied at Vout to GND 50 65 mA

NOTES:

(1) All electrical characteristics are for the application circuit on page 1.

(2) Guaranteed by design.

(3) Indefinite duration.

(4) This device is ESD sensitive. Use of standard ESD handling precautions is required.

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

PIN DESCRIPTION

Pin # Pin Name Description

1 VIN Charge pump input voltage. May be between 2.7V and 5V. VIN should be

bypassed with a >

3.3µF low ESR capacitor as close as possible to the pin

for best performance.

2 GND Ground pin.

3 VOUT Regulated output voltage. VOUT should be bypassed with a > 3.3µF low

ESR capacitor as close as possible to the pin for best performance.

4 C1+ Charge pump flying capacitor positive terminal.

5 C1- Charge pump flying capacitor negative terminal.

PIN CONFIGURATION

BLOCK DIAGRAM

Top View

SOT-23-5L

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

Typic al E ff . v s Iout (Ta = 25 Deg. C.)

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

10.0E-6 100.0E-6 1.0E-3 10.0E-3 100.0E-3

Iout (A)

Efficiency (%)

Vi n = 2. 75 V

Vi n = 3. 85 V

Vi n = 5. 00 V

Typical Eff. vs Vin (Ta = 25 Deg. C.)

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2.50 3.00 3.50 4.00 4.50 5.00 5.50

Vin (V)

Efficiency (%)

I out = 20m A

I out = 10m A

I out = 5m A

I out = 200u A

I out = 10uA

Typical Iin vs Iout (Ta = 25 Deg. C.)

000.0E+0

5.0E-3

10.0E-3

15.0E-3

20.0E-3

25.0E-3

30.0E-3

35.0E-3

40.0E-3

45.0E-3

50.0E-3

000.0E+

05.0E-3 10.0E-3 15.0E-3 20.0E-3 25.0E-3

Iout ( A)

Iin (A)

Vi n = 2. 75 V

Vi n = 3. 85 V

Vi n = 5. 00 V

Typical Output ripple vs Vin (Iout = 10mA)

30.0E-3

50.0E-3

70.0E-3

90.0E-3

110.0E-3

130.0E-3

150.0E-3

2.50 3.00 3.50 4.00 4.50 5.00 5.50

Vin (V)

Vout (V)

Cout = 3. 3 uF

Cout = 6. 8 uF

Cout = 10uF

Cout = 22uF

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

Typical Iin vs Ta (Iout = 0 A)

8.0E-6

9.0E-6

10.0E-6

11.0E-6

12.0E-6

13.0E-6

14.0E-6

0 10203040506070

Ta (Deg. C.)

Iin (A)

Vi n = 5. 00 V

Vi n = 3. 85 V

Vi n = 2. 75 V

Typical Eff. vs Ta (Iout = 10 uA)

10%

20%

30%

40%

50%

60%

70%

0 10203040506070

Ta (Deg. C.)

Efficiency (%)

Vi n = 2. 75 V

Vi n = 3. 85 V

Vi n = 5. 00 V

Typical Eff. vs Ta (Iout = 200 uA)

10%

20%

30%

40%

50%

60%

70%

80%

90%

0 10203040506070

Ta (Deg. C.)

Efficiency (%)

Vi n = 2.75 V

Vi n = 3.85 V

Vi n = 5.00 V

Typical Eff. vs Ta (Iout = 5 mA)

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10203040506070

Ta (Deg. C.)

Efficiency (%)

Vin = 2.75 V

Vin = 3.85 V

Vin = 5.00 V

Typical Eff. vs Ta (Iout = 10 mA)

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

010203040506070

Ta (Deg. C.)

Efficiency (%)

Vin = 2.75 V

Vin = 3.85 V

Vin = 5.00 V

Typical Eff. vs Ta (Iout = 20 mA)

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

010203040506070

Ta (Deg. C.)

Efficiency (%)

Vin = 2.75 V

Vin = 3.85 V

Vin = 5.00 V

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

Typi cal Vout vs Vi n (Iout = 10mA)

4.80

4.85

4.90

4.95

5.00

2.50 3.00 3.50 4.00 4.50 5.00 5.50

Vi n (V)

Vout (V)

Ta = 70 D eg. C.

Ta = 25 D eg. C.

Ta = 0 D eg. C.

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

Turn on Regulation time

Load Transient Response

Vin = 3V

2V/div.

Iout Step

0 -10 ma

Vout

50mV/div.

Vout

2V/div.

Vin = 3.0V

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

APPLICATION NOTES

THEORY OF OPERATION

The SC1517-5 utilizes a switched capacitor charge

pump, to generate an output voltage regulated to 5V+/-

4%.

An internal oscillator generates two out of phase c lock

signals which turn on and off internal MOSFET

switches. During phase1 of clock, the flying charge

pump c apacitor is charged to Vin through switches S1,

and S2. During phase2 the flying charge pump

capacitor is connected in series with the input voltage

via S3, and S4, producing an output voltage.

An integrated comparator senses the output voltage

Vout

Vin

Gnd

Cin

CoutC_charge

S1 S4

S3 S2

S1,S2

S3,S4

OFF

Charge transfer from Cin to C_charge

Charge transfer from (Cin,and C_charge) to Cout

Current Limit

Soft Start

and disable the charge pump once an upper threshold

is reached. As the output voltage drops below the lower

threshold, the comparator enables the charge pump

and hence regulation is achieved.

SHORT CIRCUIT / SOFT START

An internal current limit and soft start circuit provides

protection against output short circuit and limits large

current spikes generated during the initial start up to

charge output capacitor.

As the over current condition is applied at the output, a

com parator sens es the output voltage and com pares it

to a signal approximating VIN - 500mV.

If VOUT < VIN - 500mV, the com parator enables a 65m A

typical limited current source and the charge pump is

disabled. Once the over current is removed and

VOUT > VIN - 500m V, the cur rent source is disconnected

from output and the charge pump circuitry is enabled

again.

THERMAL SHUTDOWN

The thermal shutdown circuit provides added protection

to the SC1517-5. During a VOUT short circuit condition or

if the load is excessive (IOUT > = 20mA), the thermal

shut down circuit is active and if the junction

temper ature exceeds appr oxim ately 160°C, the char ge

pump is disabled. The charge pum p is enabled only if

the junction temperature drops to approximately 145°C.

The SC1517-5 will cycle in and out of thermal shut

down until the short circuit or the excessive load

condition on VOUT is removed, thereby improving device

reliability.

VOUT RIPPLE & CAPACITOR SELECTION

The peak to peak output ripple voltage is dependent on

the following factors:

1- Oscillator Frequency

2- Hysteresis window of the comparator

3- ESR of CCharge , and Cout

4- Capacitance value of Cout , and CCharge

Item 1, and 2 are fixed and depend on the charge

pump device used. Item 3, and 4 can be optimized for

best performance and reduction of the output ripple.

C1+

C1-

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

Capacitor Manufacturers

LAYOUT CONSIDERATION

Standard power board layout should f ollowed to ensure

proper operation. Any stray inductance should be

minimized, this can be achieved by using large power

planes or traces, and reducing the distances between

input, output and the load. All components should be

placed as close as possible to the SC1517-5.

The following formula could be used for an

approximation for Vout_ripple.

Vout_ripple=

Figure below shows the effect of output capacitance

value on the ripple voltage. Capacitors used were

multilayer ceramic with low ESR < 0.1 Ohms .

Following table shows typical capacitor characteristics :

Iout

2 Fosc Ccharge .

Iout ESR_Ccharge

Typical Output ripple vs Vin (Iout = 10mA)

30.0E-3

50.0E-3

70.0E-3

90.0E-3

110.0E-3

130.0E-3

150.0E-3

2.50 3.00 3.50 4.00 4.50 5.00 5.50

Vin (V)

Vout (V)

Cout = 3.3uF

Cout = 6.8uF

Cout = 10uF

Cout = 22uF

Component ESR

(Ohms) ESL

(nH)

0.1 uF Ceramic 0603 package 0.100 1.60

1.0 uF Ceramic 1206 package 0.120 0.47

10 uF Ceramic 1206 package 0.075 0.5

47 uF, 16V Tantalum D case 0.100 0.60

330 uF, 6.3V “OSCON” 0.025 2.5

330 uF, 16V Al Electrolytic 0.143 2.37

820 uF, 4.0V “OSCON” 0.012 2.5

1000 uF, 10V Al Electrolytic 0.053 5

Manufacturer Phone

AVX Corp. (803)-448-9411

VISHAY (207)-324-4140

Nichicon Corp. (708)-843-7500

muRata (800)-831-9172

TOKIN (408)-432-8020

Taiyo Yuden (800)-348-2496

Sanyo (619)-661-6835

MICROPOWER, RE GULATED 5V

CHARGE PUMP

SC1517-5

PRELIMINARY - April 3, 2000

DEVICE OUTLINE SO T23-5L

LAND PATTERN SOT2 3-5L

ECN00-976