LTC2921IGN-3.3 Linear Technology, LTC2921IGN-3.3 Datasheet - Page 10

• Manufacturer Part Number: LTC2921IGN-3.3
• Description: IC 5 POWER SUPPLY MONITOR 16SSOP
• Manufacturer: Linear Technology

Specifications of LTC2921IGN-3.3

• Applications: Five Power Supply Monitor
• Voltage - Supply: 2.97 V ~ 3.63 V
• Current - Supply: 2mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Input: -

LTC2921/LTC2922 Series
The timing of a circuit breaker trip and reset, and a
subsequent regular turn-on are shown in Figure 4. Prior to
time 1, a successful turn-on sequence had completed. At
time 1, excessive current pulls SENSE more than 50mV
below V
switches fall at rates determined by the pull-down currents
APPLICATIO S I FOR ATIO
Multiple supply systems have become common to accom-
modate circuits on the same board with different voltage
requirements. Desktop PC motherboards, instrumenta-
tion circuits and plug-in boards of all kinds often require
tracking and control of several supply voltages.
The LTC2921 and LTC2922 ramp and monitor up to five
supply voltages in such systems. External resistive volt-
age dividers independently program four monitor levels,
while an internal divider sets the V
level. Time delays in the monitoring sequence are set by an
external capacitor at the TIMER pin.
The GATE pin provides a high side drive voltage appropri-
ate to logic-level and sublogic-level N-channel power
10
TI I G DIAGRA S
W U
CC
. The GATE pin, PG pin, and the remote sense
U
U
W
Figure 4. Circuit Breaker Trip, Reset and Start-Up Sequence Timing
CC
W
INTERNAL
BREAKER
V
REMOTE
CIRCUIT
SWITCH
pin supply monitor
CC
SENSE
SENSE
LATCH
TIMER
-50mV
GATE
GATE
V
PG
V1
V2
V3
V4
CC
1
V
UNDERVOLTAGE
LOCKOUT LEVEL
CC
U
2 3 4
5
0.7V
0.5V
0.7V
0.5V
0.7V
0.5V
0.7V
0.5V
and loading conditions of each (times 2, 3, 4). Note that the
excessive current condition ceases at time 4. A circuit
breaker reset pulse is initiated at time 5. The latch resets
at time 6 since the V1 pulse is wide enough. A normal turn-
on begins when V1 rises above the monitor threshold
(time 7 onward).
MOSFETs. The external RC network on GATE programs
the supply ramp rate and eliminates possible high fre-
quency oscillations in the power path. Featured in the
LTC2921/LTC2922 series are sub-10
sense switches to compensate for voltage drops between
the supplies and the loads.
At the end of a successful power-on sequence, the LTC2921/
LTC2922 asserts the PG output. A typical application uses
an external pull-up resistor between PG and the load side
of a supply. In applications where supply power-on se-
quencing is required, the PG pin can function as a second,
separate high side driver.
6 7
V
CC
1.2V
V
V
CC
CC
-50mV
1.2V
internal remote
29212fa