Datasheet
LTC2930
8
2930fa
APPLICATIONS INFORMATION
Monitor Confi guration
Select the LTC2930 input voltage combination by placing
the recommended resistive divider from VREF to GND and
connecting the tap point to VPG, as shown in Figure 2.
Table 1 offers recommended 1% resistor values for each
of the 16 modes. The last column in Table 1 specifi es
optimum V
PG
/V
REF
ratios (± 0.01), when confi guring with
a ratiometric DAC.
At power-up, once V1 or V2 reaches 2.4V, the monitor
enters a setup period of approximately 150μs. During the
setup time, the voltage on the VPG pin is sampled and the
monitor is confi gured to the desired input combination. The
comparators are enabled and supply monitoring begins.
Do not add capacitance to the VPG pin.
Figure 3. Setting the Positive Adjustable Trip Point
+
–
0.5V
2930 F03
V3, V4, V5 OR V6
V
TRIP
R3
1%
R4
1%
LTC2930
2930 F04
V4
VREF
V
TRIP
R4
1%
R3
1%
LTC2930
Figure 4. Setting the Negative Adjustable Trip Point
V
SUPPLY
(V) V
TRIP
(V) R3 (kΩ) R4 (kΩ)
12 11.25 2150 100
10 9.4 1780 100
8 7.5 1400 100
7.5 7 1300 100
6 5.6 1020 100
5 4.725 845 100
3.3 3.055 511 100
3 2.82 464 100
2.5 2.325 365 100
1.8 1.685 237 100
1.5 1.410 182 100
1.2 1.120 124 100
1 0.933 86.6 100
0.9 0.840 68.1 100
*See Figure 3.
Table 2. Suggested 1% Resistor Values for the ADJ Inputs
V
SUPPLY
(V) V
TRIP
(V) R3 (kΩ) R4 (kΩ)
–2 –1.87 187 121
–5 –4.64 464 121
–5.2 –4.87 487 121
–10 –9.31 931 121
–12 –11.30 1130 121
*See Figure 4.
Table 3. Suggested 1% Resistor Values for the –ADJ Inputs
V
TR IP
= 0.5V • 1+
R3
R4
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
the negative voltage being sensed and the VREF pin, is
R1
1%
R2
1%
2930 F02
VREF
VPG
GND
LTC2930
Figure 2. Mode Selection
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
impedance, adjustable inputs (V3, V4, V5, V6). Calculate
the trip voltage from: