LTC2920-2 Linear Technology, LTC2920-2 Datasheet - Page 6

• Manufacturer Part Number: LTC2920-2
• Description: Single/Dual Power Supply Margining Controller
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
OVERVIEW
POWER SUPPLY VOLTAGE MARGINING
In high reliability PCB manufacturing and test, it is desir-
able to test system functionality and performance at the
upper and/or lower power supply voltage limits allowed
for a given design (known as “power supply margining”).
Doing so can greatly improve the lifetime reliability of a
system.
The LTC2920 provides a means of power supply voltage
margin testing which is:
• Flexible
• Easy to design
• Requires very little PCB board space
Symmetric/Asymmetric Power Supply Margining
Any one LTC2920 channel requires only a single external
resistor to symmetrically margin both above and below
the nominal power supply voltage. The LTC2920-2 can be
used to symmetrically margin two different power sup-
plies. In cases where the design calls for margining one
LTC2920-1/LTC2920-2
FU CTIO AL BLOCK DIAGRA
6
U
TO GND FOR LOW RANGE
FOR HIGH RANGE OR
U
CONNECT TO V
U
CC
U
R
SET1
R
IN1
IN2
S2
R
S1
W
LTC2920-2 ONLY
UVLO
RANGE DETECTION
INPUT DETECTION
V
THERMAL SHUTDOWN
CURRENT
SETTING
CC
U
IRNG
W
LOW
RANGE
HIGH
RANGE
voltage above the nominal power supply voltage and a
different voltage below the nominal, the LTC2920-2 can be
used. One channel is used for margining above the nomi-
nal power supply voltage, and the other channel is used to
margin below the nominal voltage.
VOLTAGE MARGINING POWER SUPPLIES USING A
FEEDBACK PIN
One common power supply architecture supported by the
LTC2920 is a power supply with a feedback pin and two
feedback resistors. Even complicated switching power
supplies can be typically modeled as a simple amplifier
with a reference voltage and a two resistor feedback
network (Figure 1).
SOURCE
OFF
SINK
I
VOLTAGE REFERENCE
PROGRAM
V
M
CONTROL
COMPLIANCE
OUTPUT
V
MOK
V
REF
R
G
+
–
–
+
Figure 1
2920-1/2 BD
R
I
FB
F
I
I
M1
M2
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2920-1/2 F01
V
PSOUT
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