Using the TPS2420, TPS2421-1 and TPS2421-2
User's Guide
Literature Number: SLUU343
January 2009
User's Guide
SLUU343 – January 2009
TPS2420 Hot Swap Controller System Test Board
This user’s guide describes the setup and operation of the TPS2420 system test board.
1
Introduction
This user’s guide describes the features of the TPS242X EVM. The TPS242X schematic, layout and List
of Materials are provided as well as a setup and getting started.
2
Description
The EVM is a 3 V to 18 V module using the TPS2420/21 hot swap controller with integrated MOSFET. At
power on, the output is power limited to control inrush current and protect the MOSFET. On an
over-current condition, the controller interrupts power to the load at high speed and signals load status.
Operating current, fault current and fault timer settings are hardware programmable.
2.1
Applications
2.1.1
Server
• Plug-In Circuit Boards
• RAID / Disk Drive
2.1.2
Telecom
• ATCA
• Micro-ATCA
2
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Block Diagram
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2.2
Features
•
•
•
•
•
•
•
•
•
•
•
3
3-V to 18-V Operation
Controlled Inrush Current
Fast Circuit Breaker Control
Hardware Programmable
– Operating Current
– Fault Current
– Fault Timer to Avoid Nuisance Tripping
– Latch Off or Retry (TPS2420 is pin selectable, TPS2421-1 is latch-off only and TPS2421-2 is re-try
only.)
LED status display
A Slide Switch Controls the ENABLE Signal.
The Area Under the TPS2420/1 is Copper Pour with Vias to the Internal Ground to take Advantage of
the Power Pad Package.
A Transorb is On-Board for Over-Voltage Input Protection
A Common Diode at the Output Prevents a Negative Spike if the Load is Removed While Powered On
Programmable IMON Voltage Readout of the Output Current is Preset to 0.31 V / A
Test Points Available to Monitor Circuit Operation
Block Diagram
POWER
TPS2420/1
LOAD+
INDICATORS
ENABLE
GND
LOAD-
Figure 1. EVM Block Diagram
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TPS2420 Hot Swap Controller System Test Board
3
Schematic
4
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Schematic
Figure 2. TPS2420 Schematic
4
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List of Materials
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5
List of Materials
This is the List of Material for the TPS242X EVM
Table 1. List of Materials
COUNT
REF DES
DESCRIPTION
PART NUMBER
MFR
2
C1, C3
Capacitor, ceramic, 0.1 µF, 603
STD
muRata
2
C2, C6
Capacitor, ceramic, 0.1 µF, 603
STD
muRata
1
C4
Capacitor, ceramic, 10V , 0.56 µF, 805
STD
muRata
1
C5
Capacitor, ceramic, 25 V, 1 µF, 1206
STD
muRata
1
D1
Diode, LED, red, 20 mA, 0.9 mcd, 0.068 x 0.049 inch
LN1271R
Panasonic
1
D2
Diode, LED, green, 20 mA, 0.9 mcd, 0.068 x 0.049 inch
LN1371G-(TR)
Panasonic
1
D3
Diode, Zener, 4.3 V, SOT23
MMBZ5229B
Motorola
1
D4
Diode, SMT TVS 400 W, 1 A, 15 V, SMA
SMAJ15A
Diodes
1
D5
Diode, Schottky, 1000 mA, 30 V, SOD123
MBR130LSFT1
STD
4
J1, J2, J4, J5
Screw terminal, 0.310 x 0.310 inch
7693
Keystone
1
J3
Header, 2 pin, 100-mil spacing, (36-pin strip), 0.100
inch x 2
PTC36SAAN
Sullins
2
Q1, Q2
Bipolar, PNP, xx-V, yy-mA, zz-W, SOT23
MMBT3906LT1
On Semi
1
R1
Resistor, chip, 0.5 W, 1%, 499 Ω, 2512
STD
STD
1
R11
Resistor, chip, 1/16 W, 1%, 24.9 kΩk, 603
STD
Vishay
1
R12
Resistor, chip, 1/16 W, 1%, 40.2 kΩ, 603
STD
Vishay
1
R13
Resistor, chip, 1/16 W, 1%, 49.9 kΩ, 603
STD
Vishay
2
R2, R3
Resistor, chip, 1/16 W, 5%, 10 kΩ, 603
STD
Vishay
2
R4, R5
Resistor, chip, 1/16 W, 1%, 1 kΩ, 603
STD
Vishay
1
R6
Resistor, chip, 1/16 W, 1%, 10 kΩ, 603
STD
Vishay
2
R7, R9
Resistor, chip, 1/16 W, 5%, 20 kΩ, 603
STD
Vishay
2
R8, R10
Resistor, chip, 1/10 W, 5%, 300 Ω, 805
STD
Vishay
1
S1
Switch, SPDT, slide, PC mount, 500 mA, 0.400 x 0.100
inch
09-03201-02
EAO
9
TP1, TP2, TP3, Test point, white, thru hole, 0.125 x 0.125 inch
TP4, TP5, TP6,
TP7, TP8, TP9
5012
Keystone
4
TP10, TP11,
TP12, TP13
Test point, SM, 0.150 x 0.090, 0.185 x 0.135 inch
5016
Keystone
0
TP14, TP15,
TP16, TP17
Test point, 0.062 Hole, 0.250 inch
5012
Keystone
1
U1
0 to 12V Integrated FET Hot Swap, QFN-16
TPS2420RSA
TI
1
U2
0 to 12V Integrated FET Hot Swap, SO8[DDA]
TPS2421-1DDA
TI
1
U2
0 to 12V Integrated FET Hot Swap, SO8[DDA]
TPS2421-2DDA
TI
1
--
Shunt, 100-mil, black
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5
Board Outline
6
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Board Outline
Figure 3. Board Outline (top)
Figure 4. Board Outline (bottom)
6
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Board Outline
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6.1
Test Points
Test Points TP14, TP15, TP16, TP17, are not installed. These are placed on the board unmarked near
Load and Load Return. This is a user option to hardwire additional capacitors, etc to the output.
Table 2. Test Points
6.2
TEST POINT
NAME
TP1
VIN
TP2
4.3 V REF
DESCRIPTION
Input voltage power supply
$0.3 V reference
TP3
EN
Enable signal, high true
TP4
FLT
Fault signal, low true
TP5
PG
Power good signal, low true
TP6
IMON
TP7
LATCH
Latch signal, high true, low for retry
TP8
VOUT
Output voltage
TP9
CT
TP10
GND
Scope ground test point
TP11
GND
Scope ground test point
TP12
GND
Scope ground test point
TP13
GND
Scope ground test point
Output current monitor, @@Volts / Amp
Fault timer capacitor
Connectors
Table 3. Connectors
CONNECTOR
6.3
DESCRIPTION
J1
Main power input, VIN
J2
Main power ground, GND
J4
Load
J5
Load ground, GND
Jumpers
Jumper J6 is used to disconnect the LEDs for test measurement of TPS2420 quiescent current. This
jumper is normally installed.
Table 4. Jumpers
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JUMPER
DESCRIPTION
J3
TPS2420 only off = latch, on = retry
J6
Installed for normal operation
TPS2420 Hot Swap Controller System Test Board
7
Equipment
6.4
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Switches
6.4.1
Enable Switch S1
The Enable slide switch turns on the hot plug controller to ramp the output voltage. When the switch is off,
the output is off.
6.5
Indicators
•
•
Green LED Indicator for Power Good (PG)
Red LED Indicator for FAULT (FLT)
7
Equipment
7.1
Equipment Needed
7.1.1
6.1.1 Voltage Source
The input voltage source, VIN is a 20-V variable dc source at 10 A.
7.1.2
6.1.3 Oscilloscope
A digital oscilloscope can be used to monitor the test points. Table 2 lists the test points.
7.1.3
6.1.4 Current Probe
A current probe is helpful to observe turn on characteristics of the external load.
7.1.4
6.1.5 Recommended Wire Gague
Power is limited to 5 W; 18 gage wire minimum is recommended.
7.2
6.2 Equipment Supplied
The TPS242x Module configured with TPS2420/21 is supplied.
Table 5. EVM Configurations
8
EVALUATION MODULE
COMPONENT
HPA270EVM-001
TPS2420
HPA270EVM-002
TPS2421-1
HPA270EVM-003
TPS2420-2
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Getting Started (example)
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8
Getting Started (example)
8.1
Equipment Connections
Reference Figure 5 for equipment connections.
• Input power supply positive voltage to J1 and negative voltage to GND, J2. Connectors J1 and J2 can
accept #6 ring or spade lugs.
• RC load at J4 and the load return at J5. The example here uses 220 µF, 15 Ω.
• Scope to current probe to measure the load current.
• Scope the VOUT - TP8, EN - TP3, PG - TP5.
Current
Probe
+
Power
Supply
12V@10A
EN/
Vout
J1
J4
220uF
15O
PG/
Scope
J2
J5
Note:
Connects to Scope
Figure 5. Equipment Connections
8.2
Operation
•
•
•
Turn on the power supply.
Trigger the scope on EN low going edge.
Slide the EN to the EN position as screened on the circuit board.
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9
Getting Started (example)
8.3
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Test Results
Observe waveforms similar to Figure 6.
• The current to the load is not constant but increases after the initial inrush. Current is low initially
because the voltage across the internal MOSFET is initially at its highest level and the controller is
power limiting the MOSFET.
VPASS = VIN - VOUT
PTPS 2420 = VPASS ´ IOUT
•
•
•
Although the current limit, IFLT, is set to 4 A, the start up current never goes above 2.2 A because of
the power limiting. However, 4 A is available to the steady state load when the MOSFET is fully
enhanced.
At the end of the capacitor charge time, the current drops to the dc level powering the resistive part of
the load, about 0.8 A.
Power Good (PG) is true when the output voltage is within 0.3 V of the input voltage.
Figure 6. Example Scope Trace
10
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This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES
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EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input voltage range of and the output voltage range of 3 VDC to 18 VDC.
Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions
concerning the input range, please contact a TI field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM.
Please consult the EVM User's Guide prior to connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than 85°C. The EVM is designed to operate
properly with certain components above as long as the input and output ranges are maintained. These components include but are not
limited to linear regulators, switching transistors, pass transistors, and current sense resistors. These types of devices can be identified
using the EVM schematic located in the EVM User's Guide. When placing measurement probes near these devices during operation,
please be aware that these devices may be very warm to the touch.
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