LTC2920-1/LTC2920-2
Single/Dual Power Supply
Margining Controller
FEATURES
■
■
■
■
■
■
■
■
■
DESCRIPTIO
Margin Voltage Precision <0.4%
400:1 Current Programming Range
Symmetric/Asymmetric High and Low Voltage
Margining
Single Control Pin per Supply—High, Float, Low
Single Current Setting Resistor per Supply
Wide V
CC
Compliance 2.3V < V
CC
< 6V
Wide Output Compliance
0.6V < V
MARGIN
< (V
CC
– 0.6V)
Single in 5-Pin ThinSOT
TM
(LTC2920-1)
Dual in 8-Pin MSOP (LTC2920-2)
The LTC
®
2920 allows power supplies and power supply
module output voltages to be precisely adjusted both up
and down for automated PCB testing. The power supply
output voltage is changed by sourcing or sinking current
into the feedback node or voltage adjust pin of the power
supply. This allows a system to test the correct operation
of electrical components at the upper and/or lower power
supply voltage limits specified for a given design (Power
Supply “Margining”).
The LTC2920 uses a single resistor to set the voltage
margining current. The margining current is adjustable
over a 400:1 range. Precision margin currents can be
supplied to within 0.6V of ground or V
CC
.
The LTC2920-1 is a single margining controller. The
LTC2920-2 has two independently controllable margining
channels. Each channel has its own control pin and current
setting resistor. The LTC2920-2 can be used to symmetri-
cally margin two power supplies, or asymmetrically mar-
gin a single power supply.
Both the LTC2920-1 and LTC2920-2 feature a trimmed on-
board voltage reference. Typical power supply margining
accuracy is better than 0.4%.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
■
■
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Automated PCB Production Testing
Automated Preventative Maintenance Testing
DC/DC Converter Module Margining
TYPICAL APPLICATIO
1
+V
IN
+V
OUT
5
3.3V Quarter Brick with
±5%
Voltage Margining
3.3V
AT 4A
150Ω
2μF
V
CC
IN1
I
M1
LTC2920-1
R
S1
GND
6
7
2920-1/2 TA01
5%
SYSTEM
CONTROLLER
THREE-STATE
R
SET1
10k
1%
–5%
LOGIC HI
IN1
LOGIC FLOAT
LOGIC LOW
1ms/DIV
+
33μF
POWER ONE
I5S013ZE-A
+
0.1μF
NOM
+V
OUT
TRIM
–V
OUT
–48V
2
–V
IN
U
2920-1/2 TA01a
U
U
292012fa
1
LTC2920-1/LTC2920-2
ABSOLUTE
(Note 1)
AXI U RATI GS
Operating Temperature Range
LTC2920-1C/LTC2920-2C ....................... 0°C to 70°C
LTC2920-1I/LTC2920-2I .................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Supply Voltage (V
CC
) ................................– 0.3V to 6.5V
Input Voltages
(IN1, IN2, R
S1
, R
S2
)................. – 0.3V to (V
CC
+ 0.3V)
Output Voltages (I
M1
, I
M2
) ........... – 0.3V to (V
CC
+ 0.3V)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
CC
1
GND 2
I
M1
3
4 R
S1
5 IN1
ORDER PART NUMBER
LTC2920-1CS5
LTC2920-1IS5
S5 PART MARKING
LTD7
LTD8
TOP VIEW
R
S2
IN2
IN1
R
S1
1
2
3
4
8
7
6
5
V
CC
I
M2
GND
I
M1
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
●
denotes the specifications which apply over the full operating
temperature range, C
RS1
= C
RS2
= 20pF, otherwise specifications are at T
A
= 25°C.
SYMBOL
Supplies
V
CC
I
CC(SOURCE)
I
CC(Q)
Supply Operating Range
Supply Current while Sourcing Max I
IM
Quiescent Supply Current
(Note 2)
R
SET1
= R
SET2
= 15k,
IN1 = IN2 < V
IL
R
SET1
= R
SET2
= 200k,
IN1 = IN2
≤
V
IL
R
SET1
, R
SET2
Tied to GND,
IN1, IN2 > V
IH
or IN1, IN2 < V
IL
, (Note 4)
R
SET1
, R
SET2
Tied to V
CC
,
IN1, IN2 > V
IH
or IN1, IN2 < V
IL
, (Note 4)
(Note 3)
●
●
●
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
Current Margining Outputs I
M1
, I
M2
I
IMLOW
I
IMHIGH
V
M
Low Range I
MARGIN
Current—
Sourcing or Sinking
High Range I
MARGIN
Current—
Sourcing or Sinking
I
M1
, I
M2
Output Voltage Compliance
●
●
●
2
U
U
W
W W
U
W
ORDER PART NUMBER
LTC2920-2CMS8
LTC2920-2IMS8
MS8 PART MARKING
LTB6
LTA4
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 200°C/W
MIN
2.3
TYP
MAX
6
6
UNITS
V
mA
mA
0.23
1
5
0.15
0.55
167
2
V
CC
– 0.55
μA
mA
V
292012fa
LTC2920-1/LTC2920-2
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
SYMBOL
I
IMACCURACY
PARAMETER
Low Range Current Accuracy
CONDITIONS
100μA
≤
⏐
I
M
⏐
≤
167μA, (Note 6)
C-Grade
I-Grade
30μA
≤
⏐
I
M
⏐
< 100μA, (Note 6)
C-Grade
I-Grade
5μA
≤
⏐
I
M
⏐
< 30μA, (Note 6)
C-Grade
I-Grade
High Range Current Accuracy
1.5mA
≤
⏐
I
M
⏐
≤
2mA, (Note 7)
C-Grade
I-Grade
600μA
≤
⏐
I
M
⏐
≤
1.5mA, (Note 7)
C-Grade
I-Grade
150μA
≤
⏐
I
M
⏐
≤
600μA, (Note 7)
C-Grade
I-Grade
I
OZ
C
IM
I
M1
, I
M2
Leakage Current
Equivalent Capacitance At I
M1
, I
M2
V
IN
= V
OFF
, (Note 5)
V
IN
= V
IL
, High Range, (Note 5)
V
IN
= V
IL
, Low Range, (Note 5)
V
CC
< 2.5V
V
CC
≥
2.5V
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
MIN
TYP
3
3
5
5
5
5
3
3
5
5
5
5
10
2
30
MAX
7.5
13
11
15
20
25
7.5
11
11
15
15
20
100
UNITS
%
%
%
%
%
%
%
%
%
%
%
%
nA
pF
nF
pF
V
V
Control Inputs IN1, IN2
V
IH
V
IL
V
OFF
V
OZ
R
IN
I
FLT
Control Voltage for I
M
Current Sinking
Control Voltage for I
M
Current Sourcing
Control Voltage for I
M
Current Off
Control Voltage when Left Floating
IN1, IN2 Input Resistance
Maximum Allowed Leakage at IN1, IN2
for I
M
Current Off
I
M1
, I
M2
Turn-On Time
I
M1
, I
M2
Turn-Off Time
I
M1
Rise Time
I
M1
Fall Time
V
IN
Transitions from V
OFF
to
V
IH
or V
IL
V
IN
Transitions from
V
IH
or V
IL
to V
OFF
⏐
I
M
⏐
5% to 95%, (Note 5)
⏐
I
M
⏐
95% to 5%, (Note 5)
2.1
2.4
0.6
1.1
1.2
5
–10
12
20
10
1.4
V
V
V
kΩ
μA
Switching Characteristics
V
IN(DELAYON)
V
IN(DELAYOFF)
I
M(ON)
I
M(OFF)
●
●
15
15
5
0.3
100
100
μs
μs
μs
μs
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
V
CC
must always be above the maximum of I
M1
and I
M2
less 0.2V.
See Preventing Potential Power Supply Overvoltages in the Applications
Information section.
Note 3:
V
M
compliance is the voltage range within which I
M1
and I
M2
are
guaranteed to be sourcing or sinking current. I
M
accuracy will vary within
this range.
Note 4:
Consult LTC Marketing for parts specified with wider I
M
current
limits.
Note 5:
Determined by design, not production tested.
Note 6:
⏐
1 – (I
M
– R
S
)
⏐
• 100%; V
CC
≤
4V: 0.58
≤
V
M
≤
(V
CC
– 1.1);
V
CC
> 4V: 0.58
≤
V
M
≤
(V
CC
– 1.4); C
RS
≤
20pF
Note 7:
⏐
1 – (I
M
• R
S
/ 30)
⏐
• 100%; 0.79
≤
V
M
≤
(V
CC
– 0.6);
C
RS
≤
20pF
292012fa
3
LTC2920-1/LTC2920-2
PI FU CTIO S
V
CC
(Pin 1/Pin 8):
Power Supply Input. All internal circuits
are powered from this pin. V
CC
should be connected to a
low noise power supply voltage between 2.3V and 6V and
should be bypassed with at least a 0.1μF capacitor to the
GND pin in close proximity to the LTC2920. Current
sourced out of the I
M
pins comes from the V
CC
pin.
Note
that V
CC
must come up no later than the time the
controlled power supply turns on or damage to the load
may result.
See Preventing Potential Power Supply Over-
voltages in the Applications Information section for power
sequencing considerations. In certain applications, it may
be necessary to further isolate V
CC
by adding a resistor in
series with its power source. See V
CC
Power Filtering in the
Applications Information section.
GND (Pin 2/Pin 6):
Ground. All internal circuits are re-
turned to the GND pin. Connect this ground pin to the
ground of the power supply(s) being margined. Current
sunk into the I
M
pins of the LTC2920 is returned to ground
through this pin.
R
S1
(Pin 4/Pin 4):
I
M1
Current Set Input. The R
S1
pin is
used to set the margining current which is sourced out of
or sunk into the I
M1
pin. The R
S1
pin must be connected to
either V
CC
or ground with an external resistor R
SET
with a
value between 6k and 200k. Connecting R
SET
to ground
sets the current at the I
M1
pin with a multiplier of 1.
Connecting R
SET
to V
CC
sets the current at the I
M1
pin with
a multiplier of 30. If R
SET
is connected to ground,
≈1V
will
appear at the R
S1
pin. If R
SET
is connected to V
CC
,
≈(V
CC
–
1V) will appear at the R
S1
pin. In either case, the current
through R
SET
will be
≈1V/R
SET
.
4
U
U
U
(S5 Package/MS8 Package)
I
M1
(Pin 3/Pin 5):
I
M1
Current Output. This pin should be
connected to the power supply feedback pin or voltage
adjust pin. (See the Applications Information section for
further details.) Current is either sourced out of or sunk
into this pin. The direction of the current is controlled by
the IN1 pin. The amount of current flowing into or out of
the I
M1
pin is controlled by the R
S1
pin.
IN1 (Pin 5/Pin 3):
I
M1
Control Pin. This pin is a 3-level input
pin which controls the I
M1
pin. If the IN1 pin is pulled above
V
IH
, current is sunk into the I
M1
pin. If the IN1 pin is pulled
below V
IL
, current is sourced from the I
M1
pin. If the IN1
pin is left floating, or held between 1.1V and 1.4V, the I
M1
pin is a high impedance output. Internally, the IN1 pin is
connected to a 1.2V voltage source by an internal ~10k
resistor. The LTC2920 has an internal RC circuit to sup-
press noise entering from this pin.
LTC2920-2 Only
R
S2
(NA/Pin 1):
I
M2
Current Set Input. Sets the current for
I
M2
. See R
S1
.
I
M2
(NA/Pin 7):
I
M2
Current Output. This pin is the second
margin current output for the LTC2920. See I
M1
.
IN2 (NA/Pin 2):
I
M2
Control Pin. This pin controls the
current at the I
M2
pin. See IN1.
292012fa
LTC2920-1/LTC2920-2
TYPICAL PERFOR A CE CHARACTERISTICS
I
CC
vs I
MARGIN
High Range
Sourcing Current
5.0
4.5
4.0
3.5
I
CC
(mA)
2 CHANNELS
ERROR (%)
I
CC
(μA)
3.0
2.5
2.0
1.5
1.0
0.5
0
0
0.5
1.5
I
MARGIN
(mA)
1
2
2.5
2920-1/2 G01
1 CHANNEL
I
MARGIN
Error vs V
MARGIN
5.0
4.5
4.0
3.5
ERROR (%)
V
CC
= 2.5V
HIGH RANGE
ERROR (%)
ERROR (%)
3.0
2.5
2.0
1.5
1.0
0.5
0
0
0.5
1
1.5
V
MARGIN
(V)
I
MARGIN
Rise Time
HIGH
RANGE
SOURCE
100%
V
IN(DELAYON)
ENDS
0%
LOW
RANGE
R
SET
= 20k
100%
HIGH
RANGE
1μs/DIV
U W
(mA)
0.15
0.3
0.5
1
2
2
2.5
2920-1/2 G04
I
CC
vs I
MARGIN
Low Range
Sourcing Current
1800
1600
2 CHANNELS
1400
1200
1000
800
600
400
200
0
0
20
40
60 80 100 120 140 160 180
I
MARGIN
(μA)
2920-1/2 G02
I
MARGIN
Error vs V
MARGIN
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
0.5
1
1.5
2 2.5 3 3.5
V
MARGIN
(V)
4
4.5
5
V
CC
= 5V
HIGH RANGE
(mA)
0.15
0.3
0.5
1
2
1 CHANNEL
2920-1/2 G03
I
MARGIN
Error vs V
MARGIN
6
5
4
3
2
1
V
CC
= 5V
LOW RANGE
0
0
0.5
1
1.5
2 2.5 3 3.5
V
MARGIN
(V)
4
4.5
5
0
50
100
166.7
(μA)
5
20
4
3
2
1
6
5
I
MARGIN
Error vs V
MARGIN
(μA)
5
20
50
100
166.7
V
CC
= 2.5V
LOW RANGE
0
0.5
1
1.5
V
MARGIN
(V)
2
2.5
2920-1/2 G06
2920-1/2 G05
I
MARGIN
Fall Time
SOURCE
V
IN(DELAYOFF)
ENDS
LOW RANGE
HIGH RANGE
0%
LOW RANGE
HIGH RANGE
100%
SINK
2920-1/2 G07
R
SET
= 20k
100%
SINK
100ns/DIV
2920-1/2 G08
292012fa
5
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