S-5470A21I-M5T1U Datasheet, PDF (9/24 Pages) Seiko Instruments Inc – ULTRA-LOW CURRENT CONSUMPTION

ULTRA-LOW CURRENT CONSUMPTION NORMALLY-OFF FAINT SIGNAL DETECTION IC
Rev.1.3_01
S-5470 Series
 Operation
The S-5470 Series detects either certain current level or the difference of current level.
The operation of the S-5470 Series is described below, using CMOS output and active "H" products as examples.
1. Basic operation when detecting certain current level (INM pin = V_SS)
The S-5470 Series operates as follows when the INM pin is connected to VSS pin.
(1) If I_INP is lower than I_DET, an "L" level signal is output from the OUT pin.
(2) If I_INP increases and becomes equal to or higher than I_DET, an "H" level signal is output from the OUT pin (point
A in Figure 14). Even if I_INP decreases and falls below I_DET, as long as I_INP is higher than I_REL, an "H" level
signal is output from the OUT pin.
(3) If I_INP then decreases further and becomes equal to or lower than I_REL, an "L" level signal is output from the
OUT pin (point B in Figure 14).
Remark I_INP: Current input to the INP pin
I_DET: Detection current (refer to "4. 1 Detection current (I_DET)")
I_REL: Release current (refer to "4. 2 Release current (I_REL)")
Caution 1.
2.
There are internal diodes at the INP pin and the INM pin. Therefore, in order to input a current
to the INP pin and the INM pin, an input voltage of at least the forward voltage of these diodes
is required.
Feed-through current (I_PEAK = 100 nA) flows around the time when the OUT pin voltage switches,
as shown in Figure 14. Therefore, if the input current is fixed around this time, the current
consumption will increase.
VDD
I_INP
INP
INM
I_INP
*1
*1
*1
+ Current
adder
−
Current
amplifier
I_DET
+
Current
comparator
−
*1
OUT
*1
VSS
*1. Parasitic diode
Figure 13 Diagram of the Operation when Detecting Certain Current Level
(1)
(2)
(3)
I_DET
I_INP
A
I_REL
B
Hysteresis width
H
OUT pin output voltage
(V_OUT)
L
Current consumption (I_DD)
I_PEAK = 100 nA
Figure 14 Operation when Detecting Certain Current Level
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