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