S-5470A21I-M5T1U Datasheet, PDF (10/24 Pages) Seiko Instruments Inc – ULTRA-LOW CURRENT CONSUMPTION

ULTRA-LOW CURRENT CONSUMPTION NORMALLY-OFF FAINT SIGNAL DETECTION IC
S-5470 Series
Rev.1.3_01
2. Basic operation when detecting the difference of current level
(Current amplifier current amplification ratio × G_INM)
The S-5470 Series operates as follows when current (I_INM) is applied to the INM pin.
(1) If I_INP is lower than I_DET + G_INM × I_INM, an "L" level signal is output from the OUT pin.
(2) If I_INP increases and becomes equal to or higher than I_DET + G_INM × I_INM, an "H" level signal is output from the
OUT pin (point A in Figure 16). Even if I_INP decreases and falls below I_DET + G_INM × I_INM, as long as I_INP is
higher than I_REL + G_INM × I_INM, 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 + G_INM × I_INM, an "L" level signal is output
from the OUT pin (point B in Figure 16).
Remark
I_INP: Current input to the INP pin
I_INM: Current input to the INM 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 16. Therefore, if the input current is fixed around this time, the current
consumption will increase.
VDD
I_INP
INP
I_INM
INM
I_INP
*1
I_INM
*1
*1
+ Current
adder
−
Current
amplifier
I_DET
+
Current
comparator
−
*1
OUT
*1
VSS
*1. Parasitic diode
Figure 15 Diagram of the Operation when Detecting the Difference of Current Level
(1)
(2)
(3)
I_DET
I_INP − G_INM × I_INM
A
I_REL
B
Hysteresis width
H
OUT pin output voltage
(V_OUT)
L
Current consumption (I_DD)
I_PEAK = 100 nA
Figure 16 Operation when Detecting the Difference of Current Level
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