SP6641AKEB-3.3 datasheet, PDF - EEWORLD Datasheet

SP6641A/6641B

Low Noise Evaluation Board

Easy Evaluation for the

SP6641A/6641B Single or

Dual Cell Alkaline to 3.3V or

5V Output

SP6641B provides up to

500mA output current with

less than 50mVpp ripple

High Efficiency: up to 87%

SOT23-5 Package & SMT

components for small, low

SP6641A/6641B Evaluation Board Schematics

J1

SHDN

1

2

3

4

SP6641A 1 OR 2 CELL BOOST

U1 SP6641A

SHDN

VOUT

GND

5

VBATT

LX

3

2

1

1uF Cer.

C3

C2

VOUT

VBATT

0.9V to 3.3V

C1

22uF

Ceramic

L1

22uH

D1

SCHOTTKY DIODE

22uF

Ceramic

J1

SHDN

1

2

3

4

SP6641B 2 CELL BOOST

U1 SP6641B

SHDN

VOUT

GND

5

VBATT

LX

3

2

1

1uF Cer.

C3

C2

330uF

40mohm

D1

L2

VOUT

VBATT

1.8V to 3.3V

C1

100uF

80mohm

L1

10uH

SM Bead

VFILTER

C4

10uF Ceramic

SCHOTTKY DIODE

USING THE EVALUATION BOARD

1) Powering Up the SP6641A/6641B Circuit

The SP6641A/6641B Evaluation Board can be powered from inputs from a +0.9V to +3.3V from

1 or 2 alkaline cells or a power supply. Connect with short leads directly to the “Vbatt” and

“Gnd” posts. Monitor the Output Voltage and connect the Load between the “Vout” post and the

“GND” post.

2) Using the J1 Jumper: Enabling the SP6641A/6641B Output and using the Shutdown

Mode

The SP6641A/6641B output will be enabled if the J1 Jumper is in the upper or pin 1 to 2

position. If J1 is in the pin 2 to 3 position, the Shutdown pin is brought to GND, which puts the

SP6641A/6641B in the low quiescent Shutdown Mode.

3) Selecting the Inductor

In selecting an inductor, the saturation current specified for the inductor needs to be greater

then the SP6641A/6641B peak current to avoid saturating the inductor, which would result in a

loss in efficiency and could damage the inductor. The SP6641A evaluation board uses a

Sumida CDRH5D28 22uH inductor with an Isat value of 0.9A and a DCR of 0.095ohms, which

easily handles the Ipeak of 0.33A of the SP6641A and will deliver high efficiencies. The

SP6641B evaluation board uses a Sumida CDRH5D28 10uH inductor with an Isat value of 1.3A

and a DCR of 0.065ohms, which easily handles the Ipeak of 1.0A of the SP6641B and will

deliver high efficiencies. Other inductors could be selected provided their Isat is greater than the

Ipeak of the SP6641A/6641B.

4) Selecting the Capacitors and Filter Components

For the SP6641A, 22uF ceramic capacitors are used, which work well due to their inherently low

ESR, which will help produce low peak to peak output ripple, and reduce high frequency spikes

as well due to their low impedance. To obtain low peak to peak ripple for the SP6641B, the

output capacitor needs to have ESR as low as 35 to 40 mohms and have a value of at least

100uF, for which the 330uF Sanyo POSCAP was chosen for its 40mohms max. ESR. Other

ultra low ESR capacitors such the radial lead 100uF Sanyo OSCON or one of the new SM low

ESR Polymer capacitors like the 100uF Panasonic UD series could be used. This low ripple is

obtained with no output spikes through the use of a LC filter consisting of small 0805 SM bead

core L2 and 10uF ceramic capacitor C3.

POWER SUPPLY DATA

Power supply data is provided for the “B” version of the SP6641B, which has a peak inductor

current limit of 1A, with the 3.3V output option. Figure 1 shows the switching signals still present

as 1.0V spikes on the 330uF capacitor C2. Note that no output spikes are seen in figures 2 and

3 through the use of a small LC filter after the 330uF capacitor. The SP6641B’s low output ripple

of 45 to 50mVpp is shown for a typical input of 2.0V to 3.0V and an output load of 300mA.

Figure 1. SP6641B Switching Signals on 330uF: Vin = 2.0V, Iout = 300mA, Spikes = 1.0Vpp

Figure 2. SP6641B Output Ripple: Vin = 2.0V, Iout = 300mA, Vout ripple = 42mVpp,

51kHz

Figure 3. SP6641B Output Ripple: Vin = 3.0V, Iout = 500mA, Vout ripple = 54mVpp,

50kHz

FIGURE 4: SP6641A/6641B COMPONENT PLACEMENT

FIGURE 5: SP6641A/6641B PC LAYOUT TOP SIDE

FIGURE 6: SP6641A/6641B PC LAYOUT BOTTOM SIDE

TABLE1: SP6641A BILL OF MATERIALS

Ref. Des. Qty.

1

2

1

5

1

Layout Size

LxWxH

Sipex Corp.

146-6447-03

1"x1.5"

Sipex Corp.

SP6641AEK-3.3 or 5.0

SOT23-5

TDK Corp

C3225X5R0J226K

1210

TDK Corp

C2012X5R1A105K

805

Sumida

CDRH5D28-220

5.7x5.5x3mm

STMicroelectronics

STPS0520Z

SOD-123

Mill-Max

0300-115-01-4727100

.042 Dia

Sullins

PTC36SAAN

.23x.12

Manufacturer

Part Number

Component

SP6641 Eval PC Board

5-pin SOT23 Step-Up DC/DC Conv

Ceramic 6.3V 22uF SM 0.005ohm ESR

Ceramic 10V 1uF SM 0.02ohm ESR

22uH, 0.90A, 0.095ohm, SM Inductor

Schottky diode 0.5A, 0.385V

Test Point Female Pin

3-Pin Header

Vendor

Sipex 978-667-8700

Sipex

TDK 847-803-6100

Sumida 847-956-0666

STMicro 847-585-3023

800-Digi-Key

U1

C1,C2

C3

L1

D1

TP

J1

TABLE2: SP6641B BILL OF MATERIALS

Ref. Des. Qty.

1

5

1

Manufacturer

Sipex Corp.

Sanyo Video

TDK Corp

Sumida

Panasonic

Zetex

Mill-Max

Sullins

Layout Size

Component

LxWxH

146-6447-03

1"x1.5"

SP6641 Eval PC Board

SP6641BEK-3.3 or 5.0 SOT23-5

5-pin SOT23 Step-Up DC/DC Conv

10TPA100M

7343

POSCAP 10V 100uF SM 0.080ohm Max. ESR

6TPB330M

7343

POSCAP 6.3V 330uF SM 0.040ohm Max. ESR

C2012X5R1A105M

805

Ceramic 10V 1uF SM 0.02ohm ESR

C3216X5R0J106M

1206

Ceramic 6.3V 10uF SM 0.005ohm ESR

CDRH5D28-100

5.7x5.5x3

10uH, 1.3A, 0.065ohm, SM Inductor

EXC-ML20A390U

805

SM Bead Core 100MHz

ZCHS2000

SOT23-6

Schottky diode 2A, 0.42V

0300-115-01-4727100 .042 Dia

Test Point Female Pin

PTC36SAAN

.23x.12

3-Pin Header

STC02SYAN

.2x.1

Shunt

Part Number

Vendor

Sipex 978-667-8700

Sipex

Sanyo 978-922-6573

TDK 847-803-6100

Sumida 847-956-0666

800-Digi-Key

Zetex 631-360-2222

800-Digi-Key

U1

C1

C2

C3

C4

L1

L2

D1

TP

J1

ORDERING INFORMATION

Model

Temperature Range

Package Type

SP6641AKEB-3.3...........................…..-40°C to +85°C...............SP6641A 3.3V Evaluation Board

SP6641AEK-3.3.....................................-40°C to +85°C......................................5-pin SOT23

SP6641AKEB-5.0.........................……… -40°C to +85°C...........SP6641A 5.0V Evaluation Board

SP6641AEK-5.0.....................................-40°C to +85°C......................................5-pin SOT23

SP6641BKEB-3.3.........................……… -40°C to +85°C...........SP6641B 3.3V Evaluation Board

SP6641BEK-3.3.....................................-40°C to +85°C......................................5-pin SOT23

SP6641BKEB-5.0.........................……… -40°C to +85°C...........SP6641B 5.0V Evaluation Board

SP6641BEK-5.0.....................................-40°C to +85°C......................................5-pin SOT23

SP6641AKEB-3.3

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