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