SP6648LED [SIPEX]

Evaluation Board Manual; 评估板手册


型号：	SP6648LED
厂家：	SIPEX CORPORATION
描述：	Evaluation Board Manual 评估板手册
文件：	总5页 (文件大小：99K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

SP6648LED

Evaluation Board Manual

ꢀ Easy evaluation for SP6648

performance of driving 1W

LumiLED.

ꢀ Plug & Light ON

ꢀ Self Protection

ꢀ Programmable Inductor Peak

Current

ꢀ High Efficiency: up to 94%

ꢀ µSOIC Package & SMT

components for small, low profile

Power Supply

DESCRIPTION AND BOARD SCHEMATIC

The SP6648LED Evaluation Board is designed to help the user evaluate the performance of

the SP6648 for use as a dual cell input to drive a 1W LumiLED. The evaluation board is a

completely assembled and tested surface mount board which provides easy probe access

points to all SP6648 inputs and outputs so that the user can quickly connect and measure

electrical characteristics and waveforms.

16K

USING THE EVALUATION BOARD

1) Powering Up the SP6648LED Circuit

The SP6648LED Evaluation Board can be powered from inputs from a +1.8V to +3.2V power

supply or from 2 alkaline cells. Connect with short leads directly to the “VIN” and “GND” posts.

Plug the 1W LumiLED between the “VOUT” and “REF” posts. Unlike other boost regulators, the

part has self-protection feature. It will not be damaged when the output is open as long as there

is a low resistance from FB to GND. As shown in Figures 1 and 2, if the board is powered up

before the LumiLED is plugged in, the circuit will bring the Feedback pin to 0V and the SP6648

has a feature to set the output voltage to be 3.3V. Once the LumiLED is plugged in, the

Feedback pin will go up to 1.25V and begin to regulate. The output voltage will go from 3.3V to

3.68V (=V_F+0.61V) accordingly (as shown in Fig. 1), where V_Fis the forward voltage of the

LumiLED. When the LumiLED is open, the Feedback pin voltage will go to 0V and the output

voltage will go to 3.3V which will protect the part (as shown in Fig 2).

V_OUT

V_REF

Fig 1. Plug in the LumiLED

Fig. 2. Unplug the LumiLED

2) Using the J1 Jumper: Enabling the SP6648 Output and using the Shutdown Mode

The SP6648 output will be enabled if the J1 Jumper is in the top 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 SP6648 in the low

quiescent Shutdown Mode.

3) Selecting the Bias Resistor

In the white LEDs application, the SP6648 is generally programmed as a current source. The

bias resistor is used to set the operating current of the white LED as equation

V_REF

R_b=

I_F

where V_REFis around 0.61V, I_Fis the operating current of the Lumiled. To set the operating

current to be about 350mA, R_bis selected as 1.8 Ohm as shown in the schematic.

4) Vout Programming

The SP6648 can be programmed as either a voltage source or a current source. To program the

SP6648 as voltage source, the SP6648 requires 2 feedback resistors R₆& R₇to control the

output voltage. To set Vout in the voltage mode, use the equation:

V_out

R₆=

−1 • R₇

0.61

5) Using the R_limFunction

The peak inductor current, I_PEAK, is programmed externally by the R_LIMresistor connected

between the RLIM pin and GND. The peak inductor current is defined by:

_PEAK= 1400/R_LIM

The SP6648 datasheet specifications for R_LIMgive a range of 1.87K to 4K ohms. Using the I_PEAK

equation above gives an I_PEAKrange of 350 to 750mA.

The saturation current specified for the inductor needs to be greater then the peak current to

avoid saturating the inductor, which would result in a loss in efficiency and could damage the

inductor. The SP6648 evaluation board uses a R_limvalue of 1.87K for an I_peak= 750mA to allow

the circuit to deliver up to 180mA for 1.3V input and 400mA for 2.6V input. Other values could

be selected using the above relationships.

6) Using the LBON - Low Battery Output Function

The SP6648 will regulate the output current until the input battery is completely discharged. To

provide an early low battery warning, the Low Battery Output function of the SP6648 switching

regulator can be used. LBON is programmed externally by the R₁and R₂resistor divider

connected between VIN, the LBI input pin and GND. When the LBI comparator falling threshold

of 0.61V is reached, D1 switches on, indicating low battery condition. Low battery detect trip

point can be calculated by the following formula:

R₁+ R₂

V_LOWBAT= 0.61

R₂

The SP6648 evaluation board R₁& R₂resistors have been set to trip for a falling battery

threshold of about 2.0V. Using this relationship, other low battery threshold values can be set

by the user.

7) Brightness Control

One approach to control LED brightness is to apply a PWM signal to the SHDN input of the

SP6648. In this case, the output current will be equal to the product of 350mA and the average

duty cycle at the SHDN pin. An additional 10K potentiometer (R₅) may also be used for dimming

LED. LED current is varied by the potentiometer between almost zero and full 350mA.

POWER SUPPLY DATA

For the standard evaluation board, The efficiency curve is shown in the figure below.

100

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

Battery Voltage (V)

Fig.3 Efficiency curve of the SP6648LED evaluation board

EVALUATION BOARD LAYOUT

FIGURE 1: SP6648LEDEB COMPONENT PLACEMENT

FIGURE 2: SP6648LEDEB PC LAYOUT TOP SIDE

FIGURE 3: SP6648LEDEB PC LAYOUT BOTTOM SIDE

TABLE1: SP6648LEDEB LIST OF MATERIALS

SP6648LED Evaluation Board List of Materials

Ref. Des. Qty. Manufacturer

Part Number

Layout Size

LxWxH

Component

Vendor

Sipex Corp.

TDK Corp TDKC3216X5R0J106K

TDK Corp TDKC1608X5R0J105K

Sumida

Rohm

Stanley

Diode Inc.

Mill-Max

Sullins

146-6510-00

SP6648EU

1"x2.14"

SP6648LED Eval PC Board

Future 888-589-3662

C1,C3

MSOP-10 10 PIN High Efficiency Boost Regulato Future 888-589-3662

1206

603

10uF/6.3V/X5R/10% Ceramic

1uF/6.3V/X5R/10% Ceramic

Future 888-589-3662

CD43-100

4x4.5x3.2mm 10uH, 1.04A, 0.18 Ohm, SM inductor Future 888-589-3662

MCR03EZPFX1003

MCR03EZPFX4322

MCR03EZPFX1501

MCR03EZPFX1622

MVR32HXBRN103

603

100K 1/16W 1% 0603 SM

43.2K 1/16W 1% 0603 SM

Open

16.2K 1/16W 1% 0603 SM

0 Ohm between pin 1 and pin 3

Open

Future 888-589-3662

603

3x3.6x1.3mm

Open

Rlim

MCR03EZPFX1871

MCR25JZHJ1R8

BR1101W-TR

1N4148W-7

0300-115-01-4701100

PTC36SAAN

603

1210

3x1.5x1.5mm

SOD-123

.042 Dia

.23x.12

1.87K 1/16W 1% 0603 SM

1.8 Ohm 1/4W 5% 1210 SM

Open

75V 150mA SM Diode

Test Point Female Pin

2-Pin Header

ORDERING INFORMATION

Temperature Range

Model

Package Type

SP6648LEDEB............................. -40°C to +85°C...................SP6648LED Evaluation Board

SP6648EU.....................................-40°C to +85°C...................................... 10-pin µSOIC

SP6648LED [SIPEX]

相关型号：

SP6648LEDEB

SP6648UEB

SP6648_06

SP6649

SP6649EU

SP6649EU/TR

SP6650

SP6650EB

SP6650EU

SP6650EU-L

SP6650EU-L/TR

SP6650EU/TR