Linear Technology DC2160A Demo Manual

DESCRIPTION

Demonstration circuit 2160A uses the
provide backup switchover, keeping the output load
powered during brown out or power loss conditions.
Priority is assigned by supply connection to the V1 and
V2 inputs. The power source connected to V1 has a higher
priority and is monitored by undervoltage switchover
threshold comparator CADJ (pin ADJ). If V1 exceeds
1.55V and ADJ is above 1.097V for 64ms, V1 is considered
valid, and the LTC4419 connects V1 to the load. If V1
drops below 1.52V, or ADJ drops below 1.047V, V1 is
considered invalid, and the LTC4419 powers the load
from V2. The DC2160A is populated to provide switchover
when V1 drops below 10.19V ±0.33V. The upper limit for
V1 is the maximum operating voltage, 18V; however, the
recommended V1 voltage is 12V. The resistive divider (R1-
R2) of the first auxiliary comparator CMP1 is adjusted to
trigger the comparator when VCMP1_TOP's voltage is in
the 9.92V to 10.74V range. Practically, any voltage from
the operating range can be selected for V2, however, 5V
is recommended to have a standard voltage level.

PERFORMANCE SUMMARY

SYMBOL PARAMETER
V1, V2, V V1, V2, V
OUT OUT
R Switch Resistance
ON
t Input Qualification Time
VALID(V1)
V ADJ Threshold
THA
V ADJ Comparator Hysteresis
HYSTA
V CMP1, CMP2 Threshold
THC
V CMP1, CMP2 Hysteresis
HYSTC
I Current Limit
LIM
V Reverse Comparator Threshold
REV
t Switch Break-Before-Make Time
SWITCH
V Demo Board Switchover Voltage
1_SWITCHOVER
V Demo Board V1 Alarmed Voltage
1_ALARM
V Demo Board V2 Alarmed Voltage
2_ALARM
LTC 4419
®
Specifications are at T
CONDITIONS
Operating Supply Range
V1 = V2 = 5V, I
V1 Rising, ADJ Rising
ADJ Falling
ADJ Rising
CMP1, CMP2 Falling
CMP1, CMP2 Rising
V1 = V2 = 8.4V
(V1, V2) – V
V1 = V2 = 5V, I
DEMO MANUAL DC2160A
18V Dual Input Micropower
PowerPath™ Prioritizer
to The second auxiliary comparator CMP2 divider (R8-R7) is
adjusted to trigger the comparator when VCMP2_TOP's
voltage is in the 3.26V to 3.53V range. Overcurrent (0.5A
to 1.6A) and thermal protection inherent to the LTC4419
allows safe prioritization. Overtemperature protection is
activated when the junction temperature exceeds 125ºC.
Another inherent feature – reverse supply protection –
protects the prioritizer and load when a negative voltage
(up to –15V) is applied to any input – V1 or V2.
The LTC4419's "break-before-make" switching method
prevents cross conduction between input channels. The
LTC4419 does not connect any input source to the load
until the input voltage exceeds the output by 50mV. This
eliminates reverse current from the output into the selected
input supply.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2160A
L, LT, LTC, LTM, Linear Technology, and the Linear logo are registered trademarks and
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
= 25°C
A
= –100μA
OUT
for Power Path Turn-On
OUT
< –10mA
OUT
LTC4419
MIN TYP MAX
1.8 18
1 2 5
34 64 94
1.032 1.047 1.062
30 50 70
0.378 0.387 0.396
7.5 10 12.5
0.5 1.1 1.6
25 50 75
1 2.5 5
9.6 9.92 10.24
9.92 10.32 10.74
3.26 3.38 3.53
dc2160af
UNITS
V
Ω
ms
V
mV
V
mV
A
mV
µs
V
V
V
1