滨松半导体光电探测器手册chapter03pdf

Illuminance sensors1 Photo IC diodes Light-to-frequency converter photo IC I2C compatible illuminance sensor 1-1 1-2 1-3 P.69 P.70 P.71 Photo IC CHAPTER 03 3 Photo IC Transmitter/receiver photo IC for optical link2 For MOST networks For AMI-C 1394 networks New approaches 2-1 2-2 2-3 P.73 P.75 P.76 P.77 Color sensors4 Digital color sensors I2C compatible color sensor 4-1 4-2 P.79 P.81 Applications7 Simple illuminometers High-speed digital transmission (application example of photo IC for optical link) LED backlight LCD display color adjustment (application example of digital color sensor) Print start timing signal output for digital copiers and laser printers (application example of photo IC for laser beam synchronous detection) 7-1 7-2 7-3 7-4 P.90 P.90 P.91 P.91 Encoder modules (displacement/rotation sensors)3 P.83Light modulation photo IC (for optical switch)5 P.86Photo IC for laser beam synchronous detection6 6 7 Photo IC 03CHA P T E R 6 8 3 Photo IC Hybrid type example Photo ICs are optical devices that combine a photosensitive section and a signal processing circuit into one package. These devices possess versatile functions according to their particular product applications. Photo ICs offer the following features compared to devices made up of discrete parts on a circuit board. · Small and lightweight · Resistant to electromagnetic induction noise · High reliability · Ideal for mass production · High cost performance Photo ICs can be broadly grouped into monolithic types and hybrid types. The monolithic type contains a photosensor and a signal processing IC formed on the same chip. This type is extremely resistant to electromagnetic induction noise because there is no wiring between the photosensor and signal processing circuit. In the hybrid type, however, the photosensor and the signal processing IC are formed on separate chips and connected to each other within one package. The hybrid type offers the advantage that specifications such as the photosensor shape and spectral response characteristics are easy to change. When designing a photo IC to custom specifications, it is important to select the photo IC type while seeking a balance between performance and cost. HAMAMATSU offers photo ICs that are optimized for a wide range of applications such as brightness and color sensing, optical links using POF (plastic optical fiber), and synchronous detection for laser printers, etc. HAMAMATSU has made intensive R&D efforts over the years to create various types of opto-semiconductor processes and unique IC processes to meet the product specifications needed by our customers. We have established a comprehensive production system ranging from photo IC design to wafer processing, assembly, and inspection processes. We also offer our strong support system for device analysis and evaluation including reliability testing. Feel free to consult with us about photo ICs that match your custom specifications. HAMAMATSU Photo ICs Application Product name Monolithic/hybrid Output Illuminance sensor Photo IC diode Monolithic Analog Light-to-frequency converter photo IC Hybrid Digital I2C compatible illuminance sensor Monolithic Digital Optical link Transmitter/receiver photo IC for optical link (For MOST network and AMI-C 1394 network) Monolithic or hybrid Digital Displacement/rotation sensor Encoder module Hybrid Digital Color sensor Digital color sensor, I2C compatible color sensor Monolithic Optical switch Light modulation photo IC, photo IC for optical switch Monolithic Print start timing detection in laser printer, etc. Photo IC for laser beam synchronous detection Hybrid Monolithic type example 6 9 Photo IC 3 [Figure 1-3] Linearity (visual-sensitive compensation type) KPICB0083EC 1 - 1 Photo IC diodes Photo IC diodes are monolithic ICs consisting of photodiodes that generate electrical current from incident light and a circuit section that amplifies the current by several tens of thousands of times. Photo IC diodes provide a current output and can be used in the same way as a photodiode applied with a reverse voltage. Photo IC diodes include visual-sensitive compensation types and infrared types with sensitivity extending to the infrared range. Packages available include SIP (single inline package), DIP (dual inline package), COB (chip on board), and head-on types. The IC and the package can be customized to match customer needs, ranging from consumer electronics to in-vehicle use. Features Just as easy to use as photodiodes Large output equivalent to phototransistors Excellent linearity Operating principle and characteristics Here we describe the operating principle of visual-sensitive compensation type photo IC diodes. The photosensitive section of visual-sensitive compensation types is made up of a photodiode for the main signal and a secondary photodiode for signal compensation. An internal arithmetic circuit subtracts the photocurrent generated in the photodiode for signal compensation from the photocurrent of the photodiode for signal detection, in order to obtain spectral response characteristics that block out the infrared range. The signal is then amplified by a current amplifier and is output. 1. Illuminance sensors [Figure 1-1] Block diagram (visual-sensitive compensation type) KPICC0163EA [Figure 1-2] Spectral response KPICB0084EB 1. Illuminance sensors 03CHA P T E R Photo IC 7 0 3 Photo IC Spectral response close to human eye sensitivity Spectral response characteristics of the photodiode used in the light-to-frequency converter photo IC are close to human eye sensitivity. The IC output nearly matches human eye sensitivity because color temperature errors are minimal. Low dark output The photodiode in the light-to-frequency converter photo IC is driven under conditions where the bias voltage between the anode and cathode is near zero. This minimizes the dark current and allows higher sensitivity. Digital output Output is in digital pulses so no troublesome analog processing is required. Operating principle and characteristics The light-to-frequency converter photo IC is made up of a photodiode and current-to-frequency converter. It outputs a pulse frequency proportional to the illuminance. Output is released during the high period of the reset pulse. The output pulse phase is initialized when the reset pulse is changed from high to low. [Figure 1-4] Block diagram KPICC0133EA Usage Apply a voltage so that a positive potential is applied to the cathode. If the high-frequency components must be removed, then connect a capacitive load (CL) as a low-pass filter in parallel with the load resistance (RL). The cut-off frequency (fc) is expressed as shown in equation (1). fc .......... (1)2π CL RL 1≈ The light-to-frequency converter photo IC is a CMOS photo IC combining a photodiode with a current-to-frequency converter. This photo IC outputs digital pulses supporting CMOS logic, and the output frequency is proportional to the incident light level. This photo IC can be used in various types of light- level sensors. Features Wide dynamic range Ordinary voltage-to-current converter circuits usually have a limited dynamic range due to the noise and supply voltage. This light-to-frequency converter photo IC employs a circuit that converts current directly to a pulse frequency. So the photocurrent of the photodiode is converted to a frequency with no loss in the wide dynamic range. This photo IC therefore achieves a dynamic range of five figures or more. [Table 1-1] Electrical and optical characteristics (visual-sensitive compensation type S9648-100) Symbol Condition Min. Typ. Max. Unit Spectral response range Peak sensitivity wavelength Dark current Photocurrent Rise time Fall time VR=5 V VR=5 V, 2856K, 100 lx 10 to 90%, VR=7.5 V RL=10 kΩ, λ=560 nm 90 to 10%, VR=7.5 V RL=10 kΩ, λ=560 nm - - - 0.18 - - 300 to 820 560 1.0 0.26 6.0 2.5 - - 50 0.34 - - nm nm nA mA ms ms λ λp ID IL tr tf 1 - 2 Light-to-frequency converter photo IC Parameter 7 1 Photo IC 3 [Figure 1-5] Spectral response KPICB0126EA [Figure 1-6] Output frequency vs. illuminance KPICB0091EC [Figure 1-7] Output waveform example Usage To detect illuminance by using the light-to-frequency converter photo IC, find the output frequency by counting the number of pulses in a specified period (Tg). The illuminance can also be detected by finding the half-cycle time of the output. This method is effective when detecting low illuminance or, in other words, during output of a low frequency. This illuminance sensor contains an I2C (inter-integrated circuit; pronounced “I-square-C”) interface. Illuminance data converted to digital signals is serially output. Ordinary illuminance sensors that provide an analog signal output require an A/D converter on the microcontroller, but this I2C compatible illuminance sensor provides a digital signal that can be directly connected to a microcontroller supporting an I2C interface. This illuminance sensor uses a chip size package (CSP) to meet needs in space-constraint applications such as cell phones. Features Supports I2C I2C is a serial interface developed by the Phillips Corporation. Two signal lines consisting of a SCL (serial clock) line and a SDA (serial data) line convey data between ICs. The I2C interface is used to connect a microcontroller to a low-speed peripheral device operating at a few hundred kilohertz, such as in cell phones. Gain switching, dynamic range (integration time), and standby function are settable from the microcontroller. Spectral response characteristics are close to human eye sensitivity. An infrared-cut filter is attached to the light receiving area to provide spectral response characteristics close to human eye sensitivity. 1 - 3 I2C compatible illuminance sensor [Figure 1-8] Connection example KPICC0134EA 1. Illuminance sensors 03CHA P T E R Photo IC 7 2 3 Photo IC Compact, thin package A WL-CSP (wafer level - chip size package) is used to ensure a small size. Structure This I2C compatible illuminance sensor is made up of a visual- sensitive compensation filter, photodiode, current-to-frequency converter, counter, timer circuit, register, I2C interface circuit, etc. The visual-sensitive compensation filter provides human eye sensitivity by blocking out infrared components and allowing only visible light to pass through the filter. The photodiode converts the light to electrical current, and the current-to-frequency converter converts the electrical current to a pulse frequency. Under low light levels the frequency is low, and under high light levels the frequency becomes higher (maximum of approx. 1 MHz). In this point, this sensor functions the same as a light-to-frequency converter photo IC. Illuminance data can be obtained by counting the pulses output from the current-to-frequency converter with the counter for a certain period of time (integration time). The timer circuit generates signals to set this integration time. The digital data obtained from the counter is then accumulated in the register and sent via the I2C interface to the microcontroller, etc. [Figure 1-9] Block diagram KPICC0135EA Characteristics The sensitivity of the I2C compatible illuminance sensor can be adjusted by setting the integration time and gain. The sensitivity (S) is proportional to the integration time and gain. S = Tint × Gain [counts/lx] Tint : integration time ............ (2) The percent of surface area used on the photodiode is different between high gain and low gain operation. The ratio of high- gain to low-gain surface area usage is 10 to 1. Integration time is selectable from four preset types (64 μs, 1 ms, 16 ms, and 128 ms). If even higher sensitivity is needed, the integration time can be set to a constant multiple [1 to 65535 (16 bits or less)] of these four types of integration times. [Figure 1-10] Count value vs. illuminance (typical example) (a) Low gain mode KPICB0151EB (b) High gain mode KPICB0152EB [Figure 1-11] Spectral response (typical example) KPICB0146EA 7 3 Photo IC 3 In-vehicle networks can be classified into those for an automotive body system, driving control system, and information system. Information system networks require higher speed and higher quality due to widespread use of digital devices. The vehicle has many noise sources, so information system networks use optical fiber communications that are not affected by external noise. Information system network standards include the MOST (Media Oriented Systems Transport) network which is widespread in Europe, and the AMI-C (Automotive Multimedia Interface Collaboration) 1394 network which is being evaluated in the United States, Japan, France, and other countries. 2 - 1 For MOST networks MOST networks utilize a ring topology that features simple node connections, easily expandable network, few connection cables, etc. Here we introduce fiber optical transceivers ( FOT) for MOST networks. To meet demands for MOST networks using FOT, we provide transmitter photo ICs that output digital pulsed light and receiver photo ICs that convert the optical signals to a digital output. Features High-speed response Data transmission speed in MOST networks is 25 Mbps, but in order to utilize high-redundancy bi-phase signals, our photo ICs achieve a physical speed of 50 Mbps which is doubled in terms of NRZ (non-return-to-zero) conversion. Digital input (transmitter photo IC) Transmitter photo ICs are digital input light-emitting devices that emit light at 650 nm which is the low-loss wavelength for POF. These photo ICs use a high-reliability LED with high emission efficiency. 2. Transmitter/receiver photo IC for optical link 2. Transmitter/receiver photo IC for optical link Package The I2C compatible illuminance sensor uses a WL-CSP (wafer level - chip size package). In conventional packages, the silicon chip is mounted on a lead frame or a substrate, and pads on the chip upper surface are connected to the lead frame or the electrodes on the substrate by wire bonding. In contrast to this, WL-CSP utilizes MEMS technology to connect pads on the chip upper surface with solder bumps on the chip backside by through-hole electrodes formed in the chip. This allows even further miniaturization. [Figure 1-12] WL-CSP cross section KPICC0151EA 1. Illuminance sensors 03CHA P T E R Photo IC 7 4 3 Photo IC Characteristics [Figure 2-3] Output waveforms (a) Transmitter photo IC: L10063-01 Horizontal axis: 5 ns/div. MOST stream data, 45.2 Mbps (b) Receiver photo IC: S10064-01B Horizontal axis: 5 ns/div., vertical axis: 1 V/div. MOST stream data, 45.2 Mbps 　 [Figure 2-4] Connection example (transmitter photo IC: L10063-01) KPICC0142EA Monolithic structure (receiver photo IC) Receiver photo ICs integrate the photodiode and signal processor into a monolithic structure to reduce effects from external electromagnetic noise. HAMAMATSU uses a unique PIN bipolar process to form the monolithic structure. This PIN bipolar process allows manufacturing photo ICs with high speed up to 250 Mbps. Standby function (receiver photo IC) In-vehicle networks require a standby function for temporarily shutting down the network except when needed in order to lower battery consumption. The standby function shifts from operating mode to standby mode when light is no longer input to the photo IC. The receiver photo IC incorporates a light-level monitor to activate the standby function. High reliability HAMAMATSU FOTs ensure the high reliability needed for in- vehicle use while housed in plastic packages which are easy to mass-produce. This allows use at operating temperatures from -40 to +105 °C. Low voltage drive Besides the standard type using an operating voltage of 4.75 to 5.25 V, HAMAMATSU also provides a low voltage type operating at 3.135 to 3.465 V. Confi guration [Figure 2-1] Block diagram (transmitter photo IC: L10063-01) KPICC0139EA [Figure 2-2] Block diagram (receiver photo IC: S10064-01B) KPICC0154EA 7 5 Photo IC 3 [Figure 2-5] Application circuit example (receiver photo IC: S10064-01B) KPICC0143EA AMI-C 1394 networks use a star topology that offers fast communication speeds along with high network efficiency and connectivity to IEEE 1394 devices such as the iPod®. Here we introduce FOT for the AMI-C 1394 network S200 (250 Mbps). These products offer a high-speed response of 250 Mbps and the high reliability needed for in-vehicle use at temperatures from -40 to 85 °C. They contain an LVDS input/output interface and can also be used for home LAN or FA (factory automation) LAN, as they send and receive the IEEE 1394 S200 data. Features Uses high-speed LED (transmitter photo IC) The transmitter photo IC employs a high-speed, high-power LED with a peak emission wavelength of 650 nm. The drive IC contains an internal temperature-compensation circuit that suppresses optical output fluctuations caused by changes in the 2 - 2 For AMI-C 1394 networks ambient temperature. Wide dynamic range and standby mode (receiver photo IC) The receiver photo IC is a hybrid structure integrating a PIN photodiode and CMOS IC, which delivers high-speed operation. It has a wide dynamic range of -2 to -22 dBm and includes a standby function that switches to power-saving mode when no light is input. Confi guration Figure 2-6 shows a block diagram of the transmitter photo IC. Operation shifts from standby mode to operation mode when an electrical signal is input to the input terminal, and the LED then emits light. A temperature monitor circuit senses the ambient temperature and adjusts the LED drive current. Figure 2-7 shows a block diagram of the receiver photo IC. When the light level exceeding a preset level enters the photodiode, operation shifts from standby mode to operation mode, then the amplifier and LVDS output circuit start operating to output an LVDS signal. [Figure 2-6] Block diagram (transmitter photo IC: L10061) KPICC0144EA [Figure 2-7] Block diagram (receiver photo IC: S10062) KPICC0145EA 2. Transmitter/receiver photo IC for optical link 03CHA P T E R Photo IC 7 6 3 Photo IC [Figure 2-10] Connection example (receiver photo IC: S10062) KPICC0147EB 2 - 3 New approaches We are currently developing new FOTs for MOST 150 which will be the next-generation MOST for attaining even faster in- vehicle networks. These FOTs will offer stable transmission at a data rate of 150 Mbps and also ensure highly reliable operation over a wide temperature range. In addition to SIP type, we will provide a SMD (surface mount device) type suitable for solder reflow mounting by assembling the transmitter/receiver chips in a single package. [Figure 2-11] FOTs for MOST 150 Characteristics [Figure 2-8] Optical output waveforms (a) Transmitter photo IC: L10061 fD=250 Mbps, PN27-1, Vcc=3.3 V, Ta=25 ˚C (b) Receiver photo IC: S10062 fD=250 Mbps, PN27-1, Vcc=3.3 V, Ta=25 ˚C, Pin=-22 dBm [Figure 2-9] Connection example (transmitter photo IC: L10061) KPICC0146EB 7 7 Photo IC 3 3. Encoder modules (displacement/rotation sensors) This is an encoder module that incorporates a red LED and a photo IC designed specifically for optical encoders. This encoder module detects the displacement or rotation angle of the object. When the slit optical pattern attached to the object moves between the LED and photo IC, the 4-element photodiode in the photo IC reads the slit optical pattern, and then outputs the pattern signals (phase A and phase B). Features