LTC2931 Linear Technology, LTC2931 Datasheet - Page 10

• Manufacturer Part Number: LTC2931
• Description: Confi gurable Six Supply Monitor
• Manufacturer: Linear Technology

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APPLICATIONS INFORMATION
LTC2931
Table 1. Voltage Threshold Modes*
*V5 and V6 are always adjustable (ADJ).
tion. The comparators are enabled and supply monitoring
begins. Do not add capacitance to the VPG pin.
Using The Adjustable Thresholds
The reference inputs on the V3 and/or V4 comparators
are set to 0.5V when the positive adjustable modes are
selected (Figure 3). The reference inputs on the V5 and V6
comparators are always set to 0.5V. The tap point on an
external resistive divider, connected between the positive
voltage being sensed and ground, is connected to the high
10
MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ)
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
V3, V4, V5 OR V6
Figure 3. Setting the Positive Adjustable Trip Point
5.0
5.0
3.3
3.3
3.3
5.0
5.0
5.0
5.0
5.0
3.3
3.3
3.3
5.0
5.0
5.0
3.3
3.3
2.5
2.5
2.5
3.3
3.3
3.3
3.0
3.0
2.5
2.5
2.5
3.3
3.3
3.0
V
TRIP
R3
1%
R4
1%
ADJ
ADJ
ADJ
ADJ
ADJ
1.5
2.5
2.5
2.5
2.5
1.8
1.8
1.8
1.8
1.8
1.8
–ADJ
–ADJ
–ADJ
–ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
1.8
1.5
1.5
+
–
0.5V
Short
Open
LTC2931
93.1
86.6
78.7
71.5
66.5
59.0
53.6
47.5
40.2
34.8
28.0
22.1
16.2
9.53
Short
Open
9.53
16.2
22.1
28.0
34.8
40.2
47.5
53.6
59.0
66.5
71.5
78.7
86.6
93.1
2931 F03
0.000
0.094
0.156
0.219
0.281
0.344
0.406
0.469
0.531
0.594
0.656
0.719
0.781
0.844
0.906
1.000
V
V
REF
PG
Table 2. Suggested 1% Resistor Values for the ADJ Inputs
Table 3. Suggested 1% Resistor Values for the –ADJ Inputs
impedance, adjustable inputs (V3, V4, V5, V6). Calculate
the trip voltage from:
In the negative adjustable mode, the reference level on the
V4 comparator is connected to ground (Figure 4). The tap
point on an external resistive divider, connected between
V
V
V
SUPPLY
SUPPLY
TRIP
–5.2
–10
–12
7.5
3.3
2.5
1.8
1.5
1.2
0.9
Figure 4. Setting the Negative Adjustable Trip Point
12
10
–2
–5
8
6
5
3
1
(V)
= 0.5V • 1+
(V)
V
TRIP
R4
1%
R3
1%
V
V
–11.30
TRIP
TRIP
–1.87
–4.64
–4.87
–9.31
11.25
4.725
3.055
2.325
1.685
1.410
1.120
0.933
0.840
2.82
9.4
7.5
5.6
7
VREF
V4
R3
R4
(V)
(V)
LTC2931
R3 (kΩ)
R3 (kΩ)
2150
1780
1400
1300
1020
1130
86.6
68.1
187
464
487
931
845
511
464
365
237
182
124
2931 F04
R4 (kΩ)
R4 (kΩ)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
121
121
121
121
121
2931fb