DEMO CIRCUIT 1594
5A Integrated Hot Swap Controller
Demonstration circuit DC1594A is a +5V or +12V rail tween Iset and GND pins, and it can be adjusted dynami-
with hot swap functionality featuring the LTC4219 - 5A cally during transient.
Integrated Hot Swap Controller. As a Controller has two The Controller monitors a load current generating ground
dedicated voltage versions- for 5.0V and 12V operation- reference signal proportional to the sense resistor volt-
the DC1594 also has similar variation-DC1594A-A (5.0V) age. Thermal limit and power good signaling increase
and DC1594A-B ((12V). The DC1594A allows evaluating Controller reliability and options in application.
performance of the LTC4219 in the transient conditions,
such as turning on and off the power rail, in the steady Design files for this circuit board are available. Call
state conditions with different load and in the fault condi- the LTC factory.
tions, when Controller interrupts its functions from over- L, LTC, LTM, LT, Burst Mode, OPTI-LOOP, Over-The-Top and PolyPhase are registered
current, nonproprietary voltage level, or thermal condi- trademarks of Linear Technology Corporation. Adaptive Power, C-Load, DirectSense, Easy
tion. Drive, FilterCAD, Hot Swap, LinearView, µModule, Micropower SwitcherCAD, Multimode
Dimming, No Latency ∆Σ, No Latency Delta-Sigma, No RSENSE, Operational Filter, PanelPro-
tect, PowerPath, PowerSOT, SmartStart, SoftSpan, Stage Shedding, SwitcherCAD, ThinSOT,
The LTC4219 features 5% accuracy in 5.4A current limit UltraFast and VLDO are trademarks of Linear Technology Corporation. Other product names
and has a current limiting foldback characteristic. Current may be trademarks of the companies that manufacture the products.
limit can be reduced by placing the external resistor be-
PERFORMANCE SUMMARY Specifications are at TA = 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VDD Input Supply Range 2.9 15 V
VDD(UVL) Input Supply Undervoltage Lockout VDD Rising 2.65 2.73 2.85 V
VOUT(PGTH)) Output Power Good Threshold LTC4219-12 Only VOUT Rising 10.2 10.5 10.8 Vo
LTC4219-5 Only VOUT Rising 4.2 4.35 4.5 V
VOUT(PGHYST) Output Power Good Hysteresis LTC4219-12 Only 127 170 213 mV
LTC4219-5 Only 53 71 89 mV
∆VGATE/∆t GATE Pin Turn-On Ramp Rate 0.15 0.3 0.55 µA
RON MOSFET+Sense Resistor ON Resistance 15 33 50 mΩ
ILIM(TH) Current Limit Threshold VFB= 1.23V 5.0 5.4 5.8 A
VFB= 0V 1.0 1.4 1.9 A
VFB= 1.23V, RSET= 20kΩ 2.3 2.7 3.2 A
VTIMER(H) TIMER Pin High Threshold VTIMER Rising 1.2 1.235 1.28 V
VTIMER(L) TIMER Pin Low Threshold VTIMER Falling 0.1 0.21 0.3 V
ITIMER(UP) TIMER Pin Pull-Up Current VTIMER =0 80 100 120 µA
ITIMER(DN) TIMER Pin Pull-Down Current VTIMER =1.2V 1.4 2 2.6 µA
ITIMER(RATIO) TIMER Pin Current Ratio ITIMER(DN)/ ITIMER(UP) 1.6 2 2.7 %
The LTC4219A-12 and LTC4219A-5 are suited accord- I 5% Accurate Current Limit for 5.4A,,
ingly for 12V and 5V power control in applications for hot I Adjustable Current Limit for lower than 5.4A,
board insertion or removal with electronic circuit breaker I Adjustable Inrush Current Control,
function, foldback current limiting, load current monitor- I Load Current Monitoring,
ing, power good and fault signaling. The LTC4219A has a I Adjustable duration for Current Limit before switch is
rich set of features to support hot swap applications in- turned off,
cluding: I Power good and Fault signaling.
QUICK START PROCEDURE
The Demo Board DC1594A includes the LTC4219-12 or load. For LTC4219-12 this time must be in the range
LTC4219-5 5A Integrated Hot Swap Controller, four LEDs (22.0-80.0) ms, and for LTC4219-5 - (9.0-34) ms.
to indicate input and output voltages (D2, D4), and the 5. Connect a Low Capacitive Load (5600uf for both
state of the fault (D3) and Power Good (D5) pins, three Controllers-LTC4219-12 and LTC4219-5) to the out-
jumpers, and a few associated components. put of hot swap circuitry (OUT turret). Turn on the
Demonstration circuit DC1594A is easy to set up to controller. This power up should be successful and
evaluate the performance of the LTC4219. Refer to Error! two LEDs (OUT –green- and PG -orange) lights must
Reference source not found. for proper measurement indicate this.
equipment setup and follow the procedure below: 6. Connect a High Reset Capacitive Load (6800uf for
The performance evaluation for LTC4219-12 and both Controllers-LTC4219-12 and LTC4219-5) to the
LTC4219-5 is identical. The difference is in a value of the output of hot swap circuitry. Turn on a controller.
loading components and power supply voltage. This power up should be unsuccessful, and no light
1. Place jumpers in the following positions: of the two LEDs, - OUT and PG,- and the light of the
FLT LED (red) confirms this. Reset controller after a
JP1 CT OFF, fault.
JP2 EN1 DISABLE, 7. Load the output with a Low Resistive Load (2.5
JP3 EN2 ENABLE. Ohms for LTC4219-12 and 1.1 Ohms for LTC4219-
2. With power off, connect the power supply termi- 5) and turn the controller on. Controller should suc-
nals to the VDD (E1) and GND (E3) turrets. cessfully keep this load. Verify performance of the
3. In all evaluations steps the Demo Board is con- 8. Load the output with a High Resistive Load (2.0
nected to the appropriative power supply (+12V or Ohms for LTC4219-12 and 0.8 Ohms for LTC4219-
+5.0V), Controller is turned on by replacing the 5) and turn the controller on. Controller should fail to
jumper head JP2 position from the DISABLE to the keep this load. Reset Controller after a fault.
ENABLE, and a resetting Controller is achieved by 9. Pay special attention to the MOSFET Safe operat-
first placing the jumper head JP2 on the DISABLE ing Area, when TIMER period is changed.
position and then on the ENABLE.
4. Place a scope probe to the output turret, turn on
the Controller, and measure a power-up time with no
Figure 1. Proper Equipment Measurement Set-Up
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