MAX16033 Datasheet, PDF (14/21 Pages) Maxim Integrated Products – Low-Power Battery Backup Circuits in Small μDFN Packages

Low-Power Battery Backup
Circuits in Small µDFN Packages
(a)
V_CC
(b)
V_CC
V_IN
R1
R2
MAX16033–
MAX16040
PFI
C1 ^R3
V_IN
R1
R2
MAX16033–
MAX16040
PFI
C1 ^R3
TO µP
PFO (PUSH-PULL)
GND
TO µP
PFO (PUSH-PULL)
GND
PFO
0V
V_{L VTRIP} V_H
V_IN
V_TRIP
=
V_PFT^{⎛⎝⎜}1 +
R1⎞
R2 ⎠⎟
V_H
=
(V_PFT +
V_PFH)^{⎛⎝⎜}1 +
R1
R2
+
R1 ⎞
R3 ⎠⎟
V_L
=
V_PFT^{⎛⎝⎜}1 +
R1 ₊
R2
R1 ⎞
R3 ⎠⎟
−
R1
R3
V_CC
V_PFT = 1.235V
V_PFH = 12mV
PFO
0V
V_TRIP
V_H
V_IN
V_TRIP
=
V_PFT^{⎛⎝⎜}1 +
R1⎞
R2 ⎠⎟
V_H
=
(V_PFT +
V_PFH)^{⎛⎝⎜}1 +
R1
R2
+
R1 ⎞
R3 ⎠⎟
−
R1
R3
V_D
V_L = V_TRIP
V_PFT = 1.235V
V_PFH = 12mV
V_D = DIODE FORWARD VOLTAGE
Figure 8. (a) Adding Additional Hysteresis to the Power-Fail Comparator. (b) Shifting the Additional Hysteresis above V_TRIP
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