PT7M7436 Datasheet, PDF (5/6 Pages) Pericom Semiconductor Corporation – Supervisory Circuit

PT7M7436/37/38
P Supervisory Circuit
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Application Information
Resistor-Value Selection (Programming the Adjustable
Thresholds)
V_REF = V_LTHIN- = V_HTHIN- = 585mV
V_TRIPLOW = V_LTH- = V_REF (
R1 + R2 + R3
R2 + R3
)
V_TRIPHIGH = V_HTL- = V_REF (
R1 + R2 + R3
R3
)
R_TOTAL = R1 + R2 + R3
Use the following steps to determine values for R1, R2, and
R3 of Functional Block Diagram.
1) Choose a value for R_TOTAL, the sum of R1, R2, and R3.
Because the PT7M7436~PT7M7438 have very high input
impedances, R_TOTAL can be up to 5MΩ.
2) Calculate R3 based on R_TOTAL and the desired upper trip
point:
× _{R3 =}
V_REF R_TOTAL
V_TRIPHIGH
× ₌
585mV R_TOTAL
V_TRIPHIGH
3) Calculate R2 based on R_TOTAL, R3, and the desired lower
trip point:
R2
=
585mV ×R_TOTAL
V_TRPLOW
- R3
4) Calculate R1 based on RTOTAL, R3, and R2:
R1 = R_TOTAL – R2 – R3
V_HTH+ = V_HTH- ×1.05, V_LTH+ = V_LTH- ×1.05
Mechanical Information
TAE (SOT23-6)
Note:
1) Controlling dimensions in millimeters.
12-07-0002
5
PKG. DIMENSIONS(MM)
SYMBOL Min
Max
A
0.70
0.90
A1
0.00
0.10
A2
0.70
0.80
b
0.35
0.50
c
0.08
0.20
D
2.82
3.02
E
1.60
1.70
E1
2.65
2.95
e
0.95 BSC
e1
1.90 BSC
L
0.30
0.60
θ
0°
8°
PT0212-6
07/05/12