LTC2901-1CGN#TR Linear Technology, LTC2901-1CGN#TR Datasheet - Page 11

• Manufacturer Part Number: LTC2901-1CGN#TR
• Description: IC MONITOR SUPPLY QUAD 16-SSOP
• Manufacturer: Linear Technology
• Type: Multi-Voltage Supervisorr

Specifications of LTC2901-1CGN#TR

• Number Of Voltages Monitored: 4
• Output: Open Drain or Open Collector
• Reset: Active Low
• Reset Timeout: 5 ms Minimum
• Voltage - Threshold: 16 Selectable Threshold Combinations
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
Power-Up
The greater of V1, V2 is the internal supply voltage (V
On power-up, V
and the COMPX pins. This ensures that the RST and COMPX
outputs will be low as soon as V1 or V2 reaches 1V. The
RST and COMPX outputs will remain low until the part is
programmed. After programming, if any one of the V
is below its programmed threshold, RST will be a logic low.
Once all the V
nal timer is started and RST is released after the pro-
grammed delay time. If V
V3 input impedance will be low (1kΩ typ).
Monitor Programming
The LTC2901 input voltage combination is selected by
placing the recommended resistive divider from V
GND and connecting the tap point to V
Figure 4. Table 1 offers recommended 1% resistor values
for the various modes. The last column in Table 1 specifies
optimum V
gramming with a ratiometric DAC.
During power-up, once V1 or V2 reaches 2.4V max, the
monitor enters a programming period of approximately
Table 1. Voltage Threshold Programming
MODE
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ)
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
PG
X
/V
inputs rise above their thresholds, an inter-
CC
REF
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
will power the drive circuits for the RST
U
ratios (±0.01) to be used when pro-
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
CC
U
< (V3 – 1) and V
–ADJ
–ADJ
–ADJ
–ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
1.8
1.5
1.5
W
Short
Open
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
PG
, as shown in
CC
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
< 2.4V, the
U
X
inputs
REF
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
CC
PG
to
).
150μs during which the voltage on the V
and the monitor is configured to the desired input combi-
nation. Do not add capacitance to the V
after programming, the comparators are enabled and
supply monitoring will begin.
Supply Monitoring
The LTC2901 is a low power, high accuracy program-
mable quad supply monitoring circuit with four nondelayed
monitor outputs, a common reset output and a watchdog
timer. Watchdog and reset timing are both adjustable
using external capacitors. Single pin programming selects
1 of 16 input voltage monitor combinations. All four
voltage inputs must be above predetermined thresholds
for the reset not to be invoked. The LTC2901 will assert the
reset and comparator outputs during power-up, power-
down and brownout conditions on any one of the voltage
inputs.
The inverting inputs on the V3 and/or V4 comparators are
set to 0.5V when the positive adjustable modes are selected
(Figure 5). The tap point on an external resistive divider,
connected between the positive voltage being sensed and
ground, is connected to the high impedance noninverting
inputs (V3, V4). The trip voltage is calculated from:
In the negative adjustable mode, the noninverting input on
the V4 comparator is connected to ground (Figure 6). The
tap point on an external resistive divider, connected be-
tween the negative voltage being sensed and the V
is connected to the high impedance inverting input (V4).
V
at ground. The trip voltage is calculated from:
REF
V
V
TRIP
TRIP
provides the necessary level shift required to operate
=
=
0 5 1
–
.
V
REF
Figure 4. Monitor Programming
V
⎛
⎜
⎝
LTC2901
⎛
⎜
⎝
+
R
R
V
GND
3
4
R
R
V
REF
PG
⎞
⎟
⎠
3
4
;
⎞
⎟
⎠
V
12
11
10
REF
=
1%
R1
1 210
.
R2
1%
2901 F04
PG
V No
PG
pin. Immediately
LTC2901
pin is sampled
min
al
11
REF
2901fb
pin,