S10317_15 Datasheet, PDF (3/6 Pages) Hamamatsu Corporation – Photo IC for laser beam synchronous detection

Photo IC for laser beam synchronous detection
S10317/S11257 series
Block diagram
Vcc
Vref
0.1 μF
3.3 V
Current
amplifier
Photodiode
Vo
Ro
GND
External
gain resistance
Ro
KPICC0127EA
Function
These products integrate a photodiode chip and an IC chip into the same package. The photodiode chip is internally connected to the IC
chip as shown in the block diagram. The products should be used with terminal Ro connected to an external gain resistance Ro.
A photocurrent is generated when a laser beam enters the photodiode. This photocurrent is fed to the input terminal of the IC and, after
being amplified by the current amplifier, flows to the external gain resistance. At this time, voltages VRO at terminal Ro is given by the
following expression.
VRO=A × S × PI × Ro [V] ·········· (1)
A: Current amplifier gain (S10317, S11257-02DT: 20 times, S10317-01, S11257-01DT: 6 times)
S: Photodiode sensitivity [A/W] (approx. 0.44 A/W at 780 nm)
PI: Input power [W]
Ro: External gain resistance [Ω]; usable range 2 kΩ to 10 kΩ
VRO is input to the internal comparator and compared with the internal reference voltage Vref (approx. 0.8 V) so the output Vo is “High”
when VRO < Vref or “Low” when VRO > Vref.
We recommend that VRO be set higher than 1.5 V but lower than 8 times of VRO calculated from equation (1) where P1 is the threshold
input power.
Also set the Ro resistance so that the Ro terminal current does not exceed the absolute maximum rating of 3 mA.
(Monitoring VRO shows that it is limited to about 2 V (with respect to GND) by the voltage limiting circuit. Keep this in mind when
monitoring.)
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