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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1029
Multi Channel Power Supply Sequencer and Supervisor
1
DESCRIPTION
LTC2928
Demonstration circuit 1029 is for evaluating the per-
formance of the LTC2928 Multichannel Power Supply
Sequencer and Supervisor.
The LTC2928 sequences and monitors up to four
power channels in power up and power down, and it
monitors those channel outputs in the steady state,
when power goes to loads. Sequencing is accom-
plished by controlling the power supply enable inputs
or N-channel MOSFET gates with the LTC2928 control-
ling outputs. Supervisory functions include undervolt-
age and overvoltage monitoring, and capturing the
output state information in the event of a system fault.
Inherent fault detection circuitry can detect:
■
Stalled (during sequencing) supplies
■
Supplies with the output voltage not satisfying the
undervoltage or overvoltage conditions
■
System controller command errors
■
Externally commanded faults
■
Sequencing faults.
The board is populated with nineteen jumpers for se-
lection of the LTC2928 operation options and with
twelve LEDs for displaying:
■
The undervoltage status in the steady state CMP1
(D5)-CMP4 (D8)
■
The LTC2928 controlling outputs states EN1 (D1)-
EN4 (D4),
■
The state signals of the ON pin (#16), the RST# pin
(#21), the OV# pin (#20), and the FLT# pin (#19).
Design files for this circuit board are available. Call the
LTC factory.
, LTC and LT are registered trademarks of Linear
Technology Corporation. ThinSOT and PowerPath
are trademarks of Linear Technology Corporation.
PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CC
V
CC
Input Supply Range
2.9 6.0 V
V
HVCC
HV
CC
Input Supply Range 7.2 12.0 16.5 V
V
ON
ON Threshold Voltage
•
V
ON
Rising
1.3 1.8 2.3 V
V
MON(TH)
Voltage Monitor Reset Threshold Voltage
VSEL=V
CC
0.492 0.500 0.508 V
V
SEQ(TH)
Sequencing Thresholds
0.67 V
MON(TH)
0.33 V
MON(TH)
0.1 V
MON(TH)
0.315
0.149
0.032
0.333
0.167
0.05
0.351
0.185
0.068
V
V
V
V
EN
Enable Pin Voltage Output in ON State V
CC
+4.5 V
CC
+5.5
V
CC
+6
I
EN(UP)
Enable Pin Pull-Up Current Enable Pin ON, V
EN•((
V
CC+4)
7.5 10 12.5 uA
t
STMR
Sequence Timer Period, STMR C
STMR=0.022UF
161 190 220 ms
t
PTMR
Power Good Timer Period C
PTMR=2.2UF
7.33
8.80 10.27 s
t
RTMR
Reset Timer C
RTMR=0.047UF
156.7
188.0 219.3 ms
V1
V2
V3
V4
V1 Internal and External Input
V2 Internal and External Input
V3 Internal and External Input
V4 Internal and External Input
2.5
1.5
1.8
3.3
V
TPV1
TPV2
TPV3
TPV4
V1 Time Position
V2 Time Position
V3 Time Position
V4 Time Position
1
3
5
7
