LTC2914IGN-2 Linear Technology, LTC2914IGN-2 Datasheet - Page 9

• Manufacturer Part Number: LTC2914IGN-2
• Description: IC,Power Supply Supervisor,CMOS,SSOP,16PIN,PLASTIC
• Manufacturer: Linear Technology

Specifications of LTC2914IGN-2

• Voltage Supervisor Type: Voltage Monitor
• Number Of Voltage Supervisors: 4
• Operating Supply Voltage (min): 2.3V
• Operating Supply Voltage (max): 6.9V
• Package Type: SSOP N
• Operating Temperature Classification: Industrial
• Operating Temp Range: -40C to 85C
• Pin Count: 16
• Mounting: Surface Mount
• Lead Free Status / Rohs Status: Not Compliant

APPLICATIONS INFORMATION
Voltage Monitoring
The LTC2914 is a low power quad voltage monitoring cir-
cuit with four undervoltage and four overvoltage inputs. A
timeout period that holds OV or UV asserted after all faults
have cleared is adjustable using an external capacitor and
is externally disabled.
Each voltage monitor has two inputs (VHn and VLn) for
detecting undervoltage and overvoltage conditions. When
configured to monitor a positive voltage V
3-resistor circuit configuration shown in Figure 1, V Hn is
connected to the high-side tap of the resistive divider and
VLn is connected to the low-side tap of the resistive divider.
If an input is configured as a negative voltage monitor, the
outputs UV
is then connected as shown in Figure 2. Note, VHn is still
connected to the high-side tap and VLn is still connected
to the low-side tap.
Polarity Selection
The three-state polarity-select pin (SEL) selects one of three
possible polarity combinations for the input thresholds,
as described in Table 1. When an input is configured for
negative supply monitoring, VHn is configured to trigger an
overvoltage condition and VLn is configured to trigger an
undervoltage condition. With this configuration, an OV con-
dition occurs when the supply voltage is more negative than
the configured threshold and a UV condition occurs when
the voltage is less negative than the configured threshold.
Figure 1. 3-Resistor Positive UV/OV Monitoring Configuration
V
n
R
R
R
n
C
B
A
and OV
VHn
VLn
LTC2914
n
+
–
in Figure 1 are swapped internally. V
0.5V
–
–
+
+
UV
OV
n
2914 F01
n
n
using the
n
The three-state input pin SEL is connected to GND, V
left unconnected during normal operation. When the pin
is left unconnected, the maximum leakage allowed from
the pin is ±10µA to ensure it remains in the open state.
Table 1 shows the three possible selections of polarity
based on the SEL pin connection.
Table 1. Voltage Polarity Programming (V
3-Step Design Procedure
The following 3-step design procedure allows selecting
appropriate resistances to obtain the desired UV and OV trip
points for the positive voltage monitor circuit in Figure 1
and the negative voltage monitor circuit in Figure 2. 1%
resistor tolerances are suggested to maintain the ±1.5%
threshold accuracy.
Figure 2. 3-Resistor Negative UV/OV Monitoring Configuration
Open
GND
SEL
V
CC
V
n
R
R
R
A
B
C
VH3 < V
VL3 > V
VH3 < V
VL3 > V
VH3 < V
VL3 > V
REF
VHn
VLn
LTC2914
V3 INPUT
Negative
Positive
Positive
+
–
UOT
UOT
UOT
UOT
UOT
UOT
0.5V
→ OV
→ OV
→ UV
→ UV
→ UV
→ OV
–
+
–
+
+
–
UOT
+
–
VH4 < V
VH4 < V
VH4 < V
VL4 > V
VL4 > V
VL4 > V
1V
LTC2914
= 0.5V Typical)
V4 INPUT
Negative
Negative
Positive
OV
UV
UOT
UOT
UOT
UOT
UOT
UOT
2914 F02
n
n
→ UV
→ OV
→ OV
→ UV
→ OV
→ UV
CC
2914fb
9
or