IS31SE5000 APPLICATION NOTE IR SENSOR FOR TOUCHLESS MOTION AND PROXIMITY GENERAL DESCRIPTION The IS31SE5000 is a low-power, reflectance-based infrared light sensor with advanced signal processing and a digital output. It interfaces to an IR (infrared) LED and two photodiodes which are monitored and programmed via a serial bus. The infrared LED is used as a light source which is picked up by two photodiodes strategically positioned on the detection hotspot. When a horizontal or proximity motion occurs an interrupt signal is generated on the INTB pin to inform the master controller to read the flag bit via the serial bus. This sensor greatly simplifies the motion detection implementation used in many touch-less applications. PIN CONFIGURATION 8 RX1 SCL 3 7 RX2 SDA Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 04/011/2013 10 VCC INTB 2 NC 6 9 NC NC 5 SDB 1 4 UTQFN-12 11 IRLED Pin Configuration (Top View) 12 GND Package 1 IS31SE5000 APPLICATION NOTE IR SENSOR FOR TOUCHLESS MOTION AND PROXIMITY TYPICAL APPLICATION CIRCUIT VBattery 10 *1 1μF VBattery VCC *3 0.1μF IRLED 11 IRLED 8 PD1 7 PD2 VDD *4 4.7kΩ 4.7kΩ 4.7kΩ *2 4 3 Micro Controller 2 1 IS31SE5000 RX1 SDA SCL RX2 INTB SDB GND 100kΩ PD1 IRLED 12 PD2 LCD Figure 1 Typical Application Circuit (For Motion Mode and Proximity Mode) VBattery 10 *1 1μF VBattery VCC *3 0.1μF IRLED 11 IRLED VDD 4.7kΩ 4.7kΩ 4.7kΩ *2 4 3 Micro Controller 2 1 100kΩ PD1 IS31SE5000 SDA SCL *4 RX1 8 PD1 INTB SDB GND 12 IRLED LCD PD1 IRLED Figure 2 Typical Application Circuit (Proximity Mode) *1: The filter capacitor which connects to VCC pin should be placed as close as possible to the IC in order to prevent voltage supply ripple. *2: The pull-up voltage for I2C and INTB pins should be greater than 1.4V. 1.8V or 2.8V is allowed. *3: The IRLED should be placed as close as possible to the IC. *4: The traces which connect to PD1 and PD2 should be short and wide. In order to prevent introduction of noise to the receive channels their PCB circuit traces should be surrounded by grounded. Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 04/011/2013 2 IS31SE5000 APPLICATION NOTE IR SENSOR FOR TOUCHLESS MOTION AND PROXIMITY COMPONENTS LAYOUT Top View with Surface Cover PD1 IRLED Top View without Surface Cover PD2 PD1 IRLED PD2 Semitransparent Window Diameter R(2mm) Horizontal Line L1(2cm) Black Cover L2(2cm) Black Isolation Wall LCD LCD Side View Semitransparent Window IRLED H<3mm Black Touch Layer Isolation Wall Black Coating Surface Cover PD1 Glue Layer Figure 3 PD2 W(4mm) W(4mm) L1(2cm) L2(2cm) PCB Components Layout (For Motion Mode and Proximity Mode ) (Note 1) 1、The IRLED and PDs (photodiodes) should be placed in the top center above the LCD screen. Placing them at the bottom is not recommended as they are more susceptible to malfunction. The IRLED should be positioned in the horizontal center between the two PDs with an evenly spaced distance of about 0.5cm~5cm apart, L1 and L2, as shown in Top View of Figure 3 above. 2、The distance ‘H’ between IRLED and surface cover should be less than 3mm. The IRLED should be surrounded by a black isolation wall (Note 2) with a width ‘W’ greater than 1.5mm. The IRLED must be fully exposed and visible through the semitransparent window (Figure 3, Side View). 3、IRLED and PD should be covered by the transparent window. The window diameter, R, should be 2mm~3mm. The windows can be lacquered with a semitransparent coating or just transparent (Figure 3, Top View). A light filter is recommended to filter out the interference light and improve the sensitivity distance. The type of light filter is dependent on the IRLED’s peak wavelength. 4、To further isolate the ambient interference light, the bottom surface cover should be lacquered with a black opaque coating, leaving the IRLED and PD windows exposed (Figure 3, Top View). 5、The black opaque surface cover should be on the side with direct contact to the black isolation wall so as to prevent interference light from getting into the IRLED cavity (Figure 3, Side View). 6、An IRLED with a peak wavelength of 850nm or 940nm, such as Everlight’s IRLED, IR11-21C/TR8 is recommended for this application. A recommended photodiode is Everlight’s PD15-22C-R/TR8. The placement of IRLED and PD can be decided by the design engineer but please pay attention to the size of IRLED and PD when doing component placement and routing PCB traces. Please read datasheets about the detail information. Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 04/011/2013 3 IS31SE5000 APPLICATION NOTE IR SENSOR FOR TOUCHLESS MOTION AND PROXIMITY Top View with Surface Cover PD1 IRLED Top View without Surface Cover Semitransparent Window Diameter R(2mm) PD1 IRLED Horizontal Line L(4mm) Black Isolation Wall Black Cover LCD LCD Side View Semitransparent Black Isolation Wall Window Black Coating Touch Layer Surface Cover H<3mm PD1 Glue Layer IRLED PCB W(1.8mm) L(4mm) Figure 4 Components Layout (For Proximity Mode ) (Note 1) 1、The IRLED and PDs (photodiodes) should be placed in the top center above the LCD screen. Placing them at the bottom is not recommended as they are more susceptible to malfunction. The IRLED should be positioned in the horizontal center with PD1 with a separation distance L of 4mm~8mm, Top View of Figure 4 above. 2、The distance ‘H’ between IRLED and surface cover should be less than 3mm. The IRLED should be surrounded by a black isolation wall (Note 2) with a width ‘W’ greater than 1.5mm. The IRLED must be fully exposed and visible through the semitransparent window (Figure 4, Side View). 3、IRLED and PD should be covered by the transparent window. The window diameter of, R, should be 2mm~3mm. The windows can be lacquered semitransparent coating or just transparent (Figure 4, Top View). The light filter is recommended to use as windows to filter the interference light and improve sensitive distance. It is decided by the peak wavelength of IRLED. 4、To further isolate the ambient interference light, the bottom surface cover should be lacquered with a black opaque coating, leaving the IRLED and PD windows exposed (Figure 4, Top View). 5、The black opaque surface cover should be on the side with direct contact to the black isolation wall so as to prevent interference light from getting into the IRLED cavity (Figure 4, Side View). 6、An IRLED with a peak wavelength of 850nm or 940nm, such as Everlight’s IRLED, IR11-21C/TR8 is recommended for this application. A recommended photodiode is Everlight’s PD15-22C-R/TR8. The placement of IRLED and PD can be decided by the design engineer but please pay attention to the size of IRLED and PD when doing component placement and routing PCB traces. Please read datasheets about the detail information. Note 1: The parameters in the figures are recommended values. Please see the detail range above for design. Note 2: The isolation wall can use 1. Black high density foam 2. Black rubber 3. Black structure wall. Elasticity material is recommended for the isolation wall to ensure there is no gap between surface cover and isolation wall. Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 04/011/2013 4 IS31SE5000 APPLICATION NOTE IR SENSOR FOR TOUCHLESS MOTION AND PROXIMITY DESIGN EXAMPLE Appearance Picture Detail Picture Black Isolation Wall Black High Density Foam Semitransparent Window (Left-Receive Window，Right-Emission Window) Figure 5 Example showing position of IRLED, isolation barrier, and Photodiodes Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 04/011/2013 5 IS31SE5000 APPLICATION NOTE IR SENSOR FOR TOUCHLESS MOTION AND PROXIMITY FAQ 1、Q: Can the IS31SE5000 operate in both Motion and/or Proximity Mode? A: Yes. When the IS31SE5000 is configured for Motion Mode (Figure 1 and 3) it can also be configured for Proximity Mode but the proximity performance might be degraded. However, when the IS31SE5000 is configured to operate in the Proximity Mode it cannot operate in the Motion Mode. In Configuration Register (11h) MODE bit (D0) is used to configure for either Motion or Proximity Mode and D3:D1 bits are used adjust the detection distance. Read only Status Register (00h) will be available after setting the operation MODE bit (D0). The MCU will read the PD bits (D3:D2) to get proximity detection information and MD bits (D1:D0) to get the Motion detection information. For example, to avoid false detection, the IS31SE5000 can be configured to operate in Proximity Mode when used in a cell phone application and receiving or making phone calls. However, when the cell phone is used to play music or read documents the IS31SE5000 can be configured for Motion Mode which will allow motion gestures to change page or play the next tune. 2、Q: What’s the greatest sensitive distance? Can it be adjusted? A: The sensitivity distance can be adjusted by programming the Configuration Register (11h) emission current (EC) bits (D3:D1). The greater the emission current, the longer sensitivity distance. Table 1 shows the sensitivity distance for various emission current settings. Table 1: Emission Current vs. Sensitive Distance Motion Mode and Proximity Mode IRLED: IR11-21C/TR8 (Everlight) PD: PD15-22C-R/TR8 (Everlight) Distance between IRLED and PD is 2cm, no cover Emission Current Proximity Mode IRLED: IR26-21C/L110/CT (Everlight) PD：PD15-22C-R/TR8 (Everlight) Distance between IRLED and PD is 4mm, no cover Sensitive Distance Sensitive Distance Hand Card (18%) 400mA 9cm 6cm 15cm 280mA 8cm 5cm 14cm 210mA 7.5cm 4cm 12cm 70mA 4.5cm 2.5cm 9cm Note, because of differences in IRLED, PD and surface cover material, the same emission current will result in different sensitivity distances. It is recommended a system test be performed to detail and confirm sensitivity distances. When operating in dual mode (Motion and Proximity) the IS31SE5000 should be configured for the Motion Mode circuit. 3、Q: How does the IRLED work with the IS31SE5000? What is the power consumption? A: The IS31SE5000 drives the IRLED at a regular pattern (Figure 6). The pulse width of the emission signal is tP = 10µs. In the Motion Mode the frequency of the emission signal tf = 80µs during operation and tf = 5.12ms in standby. Standby mode requires a longer frequency to reduce the power consumption. In the Proximity Mode the frequency tf = 5.12ms in both operation and standby modes because the power consumption is much lower than the Motion Mode. tP tf Figure 6 The Infrared Emission Signal Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 04/011/2013 6 IS31SE5000 APPLICATION NOTE IR SENSOR FOR TOUCHLESS MOTION AND PROXIMITY 4、Q: The IRLED, PD1 and PD2 are placed in the same horizontal line (Figure 3). Can the distance between IRLED and PD be different from the recommened? And what’s the effect? A: The distance between PD and IRLED will not affect the sensitivity distance (Table 2). Table 2: IRLED and PD Distance Parameter IRLED PD1 L1 PD2 L2 Distance Sensitive Distance (EC = 00) L1 = L2 = 0.5cm 9cm L1 = 0.5cm, L2 = 1cm 9cm L1 = L2 = 1cm 10cm L1 = 1cm, L2 = 2cm 10cm L1 = L2 = 2cm 10cm 5、Q: Does the IS31SE5000 have a wake up function from standby mode? A: Yes. When a device using the IS31SE5000 is in standby mode, it can be unlocked and turned on by moving a hand over the PD window(s). The Proximity Mode is recommended for this function because this mode will minimize power consumption. For example, the motion of moving the hand twice over the screen can be used to wake up a cellphone. 6、Q: Does a light filter affect the sensitivity distance? How to choose a light filter? A: Using the proper window light filter will block out ambient light and other stray interference light to improve the sensitivity distance. The proper light filter should be selected so only the IRLED peak wavelength will be let through. An 800nm light filter is recommended for the 850nm IRLEDs and an 880nm light filter is recommended for 940nm IRLEDs. 7、Q: How to maximize performance if the cover aperture and/or isolation wall is too small? A: Light sensitivity will be minimized if the cover aperture and isolation wall is too small. Applying a reflective coating on the inside of the aperture will help increase the light output. However, a wider aperture is recommended to improve sensitivity. Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 04/011/2013 7