DEMO MANUAL DC2314A
LTC4236-1/LTC4236-2
Dual Ideal Diode-OR and Single Hot
Swap Controller with Current Monitor
DESCRIPTION
Demonstration circuit 2314A is intended to demonstrate
the performance of the LTC4236-1/LTC4236-2 Dual Ideal
Diode-OR and Single Hot Swap Controller with Current
Monitor. The controller operates in redundant supply
circuits, where each rail has an individual ideal diode, and
the outputs are connected to the load through a single
Hot Swap circuit. The controller enables monitoring of
the load current by providing a signal that is 100× the
sense resistor voltage.
The DC2314A allows verification of the LTC4236 Hot Swap
and ideal diode functionality during individual rail ramp-up
and ramp-down events, during power supply switchover,
in steady state, and in overcurrent fault conditions.
The DC2314A is configured for 12V operation with a 10A
current load.
The main board components are the LTC4236 controller,
two power MOSFETs functioning as ideal diodes and one
power MOSFET controlled as a Hot Swap switch, two jump-
ers for enabling the second ideal diode and Hot Swap, four
LEDs to indicate the power good state, fault condition, and
the state of the MOSFETs operating as ideal diodes, seven
banana jacks for connecting power supplies and loads,
and many turrets and pads for observing circuit signals.
Table 1. DC2314A Assembly Options
Version
DC2314A-A
DC2314A-B
Part
LTC4236-1
LTC4236-2
Overcurrent Fault
LATCHOFF
RETRY
Design files for this circuit board are available at
http://www.linear.com/demo/DC2314A
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
BOARD AND CONTROLLER PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
SYMBOL
Supplies
V
IN
I
LIM
V
INTVCC
V
INTVCC(UVL)
ΔV
FWD(REG)
ΔV
DGATE
I
CPO(UP)
I
DGATE(FPU)
I
DGATE(FPD)
I
DGATE2(DN)
t
ON(DGATE)
t
OFF(DGATE)
t
PLH(DGATE2)
Input Supply Range
Board Current Limit
Internal Regulator Voltage
Internal V
CC
Undervoltage Lockout
Forward Regulation Voltage (V
INN
– V
SENSE
)
External N-Channel Gate Drive
(V
DGATE1
– V
IN1
) and (V
DGATE2
– V
D2SRC
)
CPO
n
Pull-Up Current
DGATE
n
Fast Pull-Up Current
DGATE
n
Fast Pull-Down Current
DGATE2 Off Pull-Down Current
DGATE
n
Turn-On Delay
DGATE
n
Turn-Off Delay
D2OFF Low to DGATE2 High
IN < 7V, ΔV
FWD
= 0.15V; I = 0, –1µA
IN = 7V to 18V, ΔV
FWD
= 0.15V; I = 0, –1μA
CPO = IN = D2SRC = 2.9V
CPO = IN = D2SRC = 18V
ΔV
FWD
= 0.2V, ΔV
DGATE
= 0V, CPO = 17V
ΔV
FWD
= –0.2V, ΔV
DGATE
= 5V
D2OFF = 2V, ΔV
DGATE2
= 2.5V
ΔV
FWD
= 0.2V, C
DGATE
= 10nF
ΔV
FWD
= –0.2V, C
DGATE
= 10nF
50
INTV
CC
Rising
OUT = 11V
2.9
8.91
4.5
2.1
2
5
10
–60
–50
10
5
2.2
15
7
12
–100
–90
–1.5
1.5
100
0.25
0.2
50
200
0.5
0.5
100
18.0
11.11
5.5
2.3
28
14
14
–130
–120
V
A
V
V
mV
V
V
µA
µA
A
A
µA
µs
µs
µs
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PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Ideal Diode Control
1
DEMO MANUAL DC2314A
BOARD AND CONTROLLER PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
SYMBOL
ΔV
SENSE(TH)
V
SENSE+(UVL)
ΔV
SENSE+(HYS)
ΔV
HGATE
ΔV
HGATE(H)
I
HGATE(UP)
I
HGATE(DN)
I
HGATE(FPD)
Input/Output Pin
V
IN(TH)
V
ON(RESET)
V
D2OFF(H,TH)
V
TMR(H)
I
FTMR(UP)
I
FTMR(DN)
Current Monitor
G
IMON
V
IMON(MAX)
R
IMON(OUT)
IMON Voltage Gain
IMON Maximum Output Voltage
IMON Output Resistance
ΔV
SENSE
= 20mV and 5mV
ΔV
SENSE
= 70mV, 5V ≤ SENSE
+
≤ 18V
ΔV
SENSE
= 35mV, SENSE
+
= 2.9V
ΔV
SENSE
= 200μV
99
3.5
2.7
15
20
100
101
5.5
2.9
27
V/V
V
V
kΩ
ON, FB Pin Threshold Voltage
ON Pin Fault Reset Threshold Voltage
D2OFF Pin High Threshold
FTMR, DTMR Pin High Threshold
FTMR Pull-Up Current
FTMR Pull-Down Current
FTMR = 1V, in Fault Mode
FTMR = 2V, No Faults
Voltage Rising
ON Falling
D2OFF Rising
1.21
0.57
1.21
1.198
–80
1.3
1.235
0.6
1.235
1.235
–100
2
1.26
0.63
1.26
1.272
–120
2.7
V
V
V
V
μA
μA
PARAMETER
Current Limit Sense Voltage Threshold
(V
SENSE+
– V
SENSE–
)
SENSE
+
Undervoltage Lockout
SENSE
+
Undervoltage Lockout Hysteresis
External N-Channel Gate Drive (V
HGATE
– V
OUT
) IN < 7V, I = 0, –1μA
IN = 7V to 18V, I = 0, –1μA
Gate High Threshold (V
HGATE
– V
OUT
)
External N-Channel Gate Pull-Up Current
External N-Channel Gate Pull-Down Current
Gate Drive On, HGATE = 0V
Gate Drive Off, OUT = 12V, HGATE = OUT +5V
CONDITIONS
FB = 1.3V
FB = 0V
SENSE
+
Rising
MIN
22.5
5.8
1.8
10
5
10
3.6
–7
1
100
TYP
25
8.3
1.9
50
7
12
4.2
–10
2
200
MAX
27.5
10.8
2
90
14
14
4.8
–13
4
350
UNITS
mV
mV
V
mV
V
V
V
μA
mA
mA
Hot Swap Diode Control
External N-Channel Gate Fast Pull-Down Current Fast Turn-Off, OUT = 12V, HGATE = OUT +5V
2
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DEMO MANUAL DC2314A
OPERATING PRINCIPLES
The LTC4236 is intended to build a combination of a diode-
OR circuit for two rails and a common single Hot Swap
path for inrush current limiting and overcurrent protection.
The LTC4236 regulates the forward voltage drop across
the ideal diode MOSFET to ensure smooth current transfer
from one supply to the other without oscillation. A fast
ideal diode MOSFET turn-on reduces the load voltage
droop during supply switchover. If the input supply fails
or is shorted, a fast turn-off minimizes reverse current
transients.
The Hot Swap fast acting current limit and internal timed
circuit breaker protect circuit components when a short-
circuit fault occurs.
The Hot Swap section of the LTC4236 has independent
on/off control (ON pin).
Each ideal diode MOSFET is activated from an individual
charge pump source, and the second one has an additional
on/off control (D2OFF pin).
The LTC4236 features an adjustable debounce time — the
delay time between events when the controller is enabled
and when it starts up.
The DC2314A-A (LTC4236-1) circuit features a latchoff
circuit breaker, and DC2314A-B (LTC4236-2) provides
automatic retry after a fault.
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DEMO MANUAL DC2314A
BANANA JACKS WITH ASSOCIATED TURRETS
IN1 (E1, E2): First rail input.
IN2 (E5, E6): Second rail input.
GND (E3, E4, E7, E8, E14, E15, E21, E22): Power and control ground.
SENSE
+
(E16, E26): SENSE
+
power node.
OUT (E12, E13): Circuit output for load connection.
TURRETS
ON (E18): Hot Swap ON control input.
EN
(E19): Enable input.
D2OFF (E20): Enable ideal diode 2.
PWRGD
(E9): Power status output.
FAULT
(E10): Fault status output.
CMON (E11): Current sense monitoring output.
JUMPERS
JP1 (ON_SEL): Hot Swap ON control signal selection.
JP2 (EN_SEL): ENABLE signal selection.
JP3 (DIODE2_OFF): Diode 2 OFF-ON control.
JP4 (PPRI_SEL): Prioritizer function selection.
JP5 (FB_SEL): Foldback circuit selection.
JP6 (DEBOUNCE): Debounce time selection.
JP8 (DSTAT2_SEL):
DSTAT2
pin functionality selection.
JP9 (D2OFF_SEL): D2OFF control in the prioritizer mode.
LEDS
D3: Indicates
PWRGD
pin signal.
D4: Indicates
FAULT
pin signal.
D5: Indicates
DSTAT1
pin signal.
D6: Indicates
DSTAT2
pin signal.
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DEMO MANUAL DC2314A
QUICK START PROCEDURE
Demonstration circuit 2314A is easy to set up to evalu-
ate LTC4236. Refer to Figure 1 for proper measurement
equipment setup and follow the procedure below:
The DC2314A test includes independent test of the LTC4236
Hot Swap functionality and ideal diode functionality.
HOT SWAP FUNCTIONALITY TEST
This test is performed with singe rail operation when the
output is provided through two series connected MOSFETs.
One MOSFET functions as an ideal diode and the other
one as a Hot Swap circuit switch.
The parameters of four different transients completely
characterize the Hot Swap circuit performance. These
transients are:
A Power-Up Without Any Additional Load
A Current Limit Operation After Successful Power-Up
A Power-Up With Shorted Output
A Power-Up With Pure Capacitive Load For Confirming
Foldback Current Limiting
1. Initially, install the jumpers in the following positions,
if the first ideal diode is used in the test:
JP1 ON_SEL in the position OFF
JP2 EN_SEL in the position EN
JP3 DIODE2_OFF in the position OFF_EXT
If the second ideal diode is used:
JP1 ON_SEL in the position OFF
JP2 EN_SEL in the position EN
JP3 DIODE2_OFF in the position ON
Connect a +12V power supply to turrets IN1 (or IN2)
and GND. Do not load the output. Place the current
probe on the +12V wire, voltage probes on the OUT
turret and a voltmeter on the CMON and GND turrets.
Provide an ON signal at the ON pin by changing the JP1
header position from the OFF position to 12V. Observe
the transient. The output voltage rise time should be in
the range of 8.3ms – 19.7ms. The
PWRGD
green LED
D3 must light up. The voltmeter at the CMON turret
should display an absolute value not larger than 15mV.
Turn off the rail using the ON_SEL jumper.
2. Connect a disabled electronic load to the OUT turret
and GND. Turn on the rail and slowly increase the load
current up to the circuit breaker threshold level. The
current limit range should be from 8.91A to 11.11A.
The voltage at the CMON turret should be in the range
from 2.18V to 2.83V. Turn off the rail with the ON_SEL
jumper.
3. Initially short the output with an external wire. Place the
current probe on this wire. Turn on the rail and record
the current shape. The maximum current should be in
the 2.30A to 4.36A range, and the voltage at the CMON
turret should be in the range from 0.57V to 1.09V.
4. With no rail voltages and JP1 in the OFF position, connect
a 1000μF capacitor to the board output. Place a scope
current probe on any wire between the board and the
1000μF capacitor, and a voltage probe at the output.
Provide +12V to any input (IN1 or IN2) and enable the
ON signal. Confirm that current limit is characterized
by a foldback functionality.
IDEAL DIODE FUNCTIONALITY TEST
In this test, both ideal diodes are active and small varia-
tions in the input voltage forces one ideal diode to be off
and the other ideal diode to be on.
Connect input turrets (IN1 and IN2) of each ideal diode
with individual independent lab supplies. Adjust each input
voltage to +12V with maximum possible accuracy. Place
one voltmeter between IN1 and IN2 turrets to measure
the difference between the two input voltages. Connect an
electronic load to the output turret. Activate both rails and
keep the load around 1A to 3A. Play with the input voltage
levels and be sure that when the difference between input
voltages exceeds 28mV, only one rail feeds the load.
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