ETC CM3109

PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
2A Sink/Source Regulator
for Front Side Bus and DDR Memory Bus Termination
Features
•
Product Description
Ideal for both PC Front Side Bus and DDR
memory VTT applications
Sinks and sources 2A
Over current protection
Over temperature protection
Shutdown functionality
Integrated power MOSFETs.
Excellent accuracy (0.5% of load regulation)
Minimum external components
8 pin SOIC and PSOP packages
•
•
•
•
•
•
•
•
Applications
•
•
•
•
PC Front Side Bus termination
DDR Memory Termination.
Active Termination Buses.
Graphics Card DDR Memory Termination.
The CM3109 is a sinking and sourcing regulator
specifically designed for series-parallel bus termination for
high speed chip set buses as well as DDR memory
systems. It can source and sink current up to 2A with high
accuracy of 0.5 %. The VTT output voltage is selectable by
VDDQSEL and FSBSEL pins. The VDDQSEL pin controls
whether the CM3109 is in DDR memory mode with VTT =
VDDQ/2, or in FSB mode. In FSB mode, FSBSEL controls
whether VTT is 1.225V or 1.45V. This allows the same
chip to be used in two different circuits on PC
motherboards that support both Northwood and Prescott
processors.
The CM3109 requires no external components to use the
GMCH Enable signal in Intel chipset or corresponding
signals for other chip sets when powering up the PC. For
the boards which support Suspend to RAM (STR)
functionality, CM3109 provides a shutdown (SD#) pin.
When SD# is set low, VTT will be in tri-state mode, causing
the output to go high impedance. In this mode, CM3109
power is saved by significantly reducing the quiescent
current.
The CM3109 provides over current and over temperature
protection. These features protect the chip from excessive
heating due to high current and high temperature. The
CM3109 is available in both 8-pin SOIC and PSOP
packages.
Simplified Electric Schematic
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
1
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
PACKAGE/PIN DIAGRAM
PIN DESCRIPTIONS
PIN
1
2
3
4
5
6
7
8
SYMBOL
VDDQ
VTT
SD
VSENSE
FSBSEL
GND
VDDQSEL
VCC
DESCRIPTION
Input Voltage VDDQ
Output 1.225V/1.45V FSB or VDDQ/2 DDR (note1)
Shutdown
Feedback Input
Select Input for FSB Output Voltage 1.225V/1.45V
Ground
Select Input for DDR/FSB Output
Power for Control Blocks
Table1. VTT Output Selection Truth Table.
VDDQSEL
"1"
OPEN or "0"
OPEN or "0"
FSBSEL
Don't Care
"0"
"1"
VTT
VDDQSEL/2(note1)
1.225V
1.45V
Note
For DDR
For FSB
For FSB
Note1: Assume VDDQ and VDDQSEL are tide together in the DDR application.
STANDARD PART ORDERING INFORMATION
Pins
Package
Ordering Part Number
Part Marking
8
SOIC
CM3109-00SN
CM3109-00SN
8
PSOP
CM3109-00SB
CM3109-00SB
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
2
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
Specifications
Absolute Maximum Ratings
Parameter
Rating
VCC Operating Supply Voltage
7
VDDQ Input Voltage
7
Pin Voltages
VTT Output
7
Any Other Pins
7
ESD Protection (HBM)
2000
Storage Temperature Range
-40 to +150
Operating Temperature Range
Ambient
-45 to +85
Junction
-45 to +150
Note2
Power Dissipation
Internally Limited
Unit
V
V
V
V
V
°C
°C
°C
W
Note 2: The devices must be derated based on thermal resistance at elevated temperature.
The CM3109-xxSN must be derated at θJA = 151°C/W.
Standard Operating Conditions
Parameter
Range
VDDQ, VCC , VDDQSEL
2.5
Ambient OperatingTemperature
25
COUT
220 ± 20%
Unit
V
°C
µF
Electrical Operating Characteristics 3
Conditions
Symbol
VDDQ
VCC
ICC
Parameter
Input Voltage Range VDDQ
Input Voltage Range VCC
VCC Quiescent Current
VTT
Output Voltage
VR LOAD
Load Regulation
ILim
VFSBSEL
VSD
VTT Current Limit
Output Selection Logic
(FSBSEL)
Shutdown Logic
TDISABLE
THYST
Shutdown temperature
Thermal hysteresis
MIN
2.2
2.2
TYP
2.5
2.5
450
MAX
VCC
5.5
UNIT
V
V
µA
1.225
1.2
1.425
1.25
1.225
1.45
1.275
1.25
1.475
V
V
V
1.2
1.425
1.225
1.45
6.25
1.25
1.475
V
V
mV
IVTT = 0A
IVTT = 0A, VDDQ = 2.5V
VDDQSEL = "1" = 2.5V
VDDQSEL = "0", FSBSEL = "0"
VDDQSEL = "0", FSBSEL = "1"
IVTT = 0A, VDDQ = 3.3V
VDDQSEL = "0", FSBSEL = "0"
VDDQSEL = "0", FSBSEL = "1"
IVTT = 0A to 2A or IVTT = -2A to 0A
2.5
Logic "1" Level
Logic "0" Level
Logic "1" Level
Logic "0" Level
1.5
0.4
1.5
0.4
150
50
A
V
V
V
V
°C
°C
Note 3: Operating characteristics are over Standard Operating Conditions unless otherwise specified.
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
3
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
Performance Information
Typical DC Characteristics (nominal conditions unless specified otherwise)
Output Voltage with Supply (VDDQSEL=2.5V)
Load Regulation (Sink)
Reference Voltage with Supply (VDDQSEL = 2.5V)
Load Regulation (Source)
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
4
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
Performance Information (cont'd)
Typical DC Characteristics (nominal conditions unless specified otherwise)
Over Current Limit (Source)
Over Current Limit (Sink)
Output Voltage with Supply Voltage (VDDQSEL=0V,
FSBSEL=0
Output Voltage with Supply Voltage (VDDQSEL=0V,
FSBSEL=2.5V)
Supply Current with Supply Voltage
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
5
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
Performance Information (cont'd)
Typical Transient Characteristics (nominal conditions unless specified otherwise)
Load Transient (0A to 1.5A Sink)
Line Transient (0A to 1.5A Source)
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
6
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
Typical Thermal Characteristics
The overall junction to ambient thermal
resistance (θJA) for device power dissipation (PD)
consists primarily of two paths in series. The first
path is the junction to the case (θJC) which is
defined by the package style, and the second
path is case to ambient (θCA) thermal resistance
which is dependent on board layout. The final
operating junction temperature for any set of
conditions can be estimated by the following
thermal equation:
CM3109-00SN and maximum instantaneous
current of 2A should not be exceeded 29% of the
time. For CM3109-00SB, the maximum RMS
current increases from 1.3A to 2.2A. Thus, the
maximum continuous current can be 2A all the
time.
Duty Cycle vs. Ambient Temperature (2A)
TJUNC = TAMB + PD (θJC ) + PD (θCA )
= TAMB + PD (θJA)
When a CM3109–00SN (SOIC) is mounted on a
double sided printed circuit board with two square
inches of copper allocated for “heat spreading,"
the resulting θJA is 151°C/W. Based on the over
temperature limit of 150°C with an ambient of
85°C, the available power of this package will be:
PD = (150°C - 85°C) / 151°C/W = 0.43W.
For the CM3109-00SB (PSOP) the θJA is 40°C/W,
and the available power for this package will be:
PD = (150°C -85°C) / 40°C/W = 1.625W.
Duty Cycle vs. Output Current (70C)
DDR Memory Application
Since the output voltage is 1.25V, and the device
can either source current from VDDQ or sink
current to Ground, the power dissipated in the
device at any time is 1.25V times the current load.
This means the maximum average RMS current
(in either direction) is 0.344A for CM3109-00SN
and 1.3A for CM3109-00SB. The maximum
instantaneous current is specified at 2A, so this
condition should not be exceeded 17% and 65%
of the time for CM3109-00SN and CM3109-00SB,
respectively. It is highly unlikely in most usage of
DDR memory that this might occur, because it
means the DDR memory outputs are either all
high or all low for 17% (SOIC) and 65% (PSOP)
of the time.
If the ambient temperature is 40°C instead of
85°C, which is typically the maximum in most
DDR memory applications, the power dissipated
PD can be 0.73W for CM3109-00SN and 2.75W
for CM3109-00SB. So the maximum average
RMS current increases from 0.42A to 0.58A for
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
7
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
Typical
(cont')
Thermal
Characteristics
The CM3109-00SB has a heat spreader attached to
the underneath of the PSOP-8 package in order for
heat to be transferred much easier from the package
to the PCB. The heat spreader is a copper pad of
dimensions just smaller than the package itself. By
positioning the matching pad on the PCB top layer to
connect to the spreader during manufacturing, the
heat will be transferred between the two pads. The
drawing below shows the recommended PCB layout.
Note that there are six vias on either side to allow
the heat to dissipate into the ground and power
planes on the inner layers of the PCB. Vias can be
placed underneath the chip, but this can cause
blockage of the solder. The ground and power
planes should be at least 2 sq in. of copper by the
vias. It also helps dissipation to spread if the chip is
positioned away from the edge of the PCB, and not
near other heat dissipating devices. A good thermal
link from the PCB pad to the rest of the PCB will
ensure a thermal link from the CM3109 package to
ambient, θJA, of around 40°C/W.
Top layer copper connects to heat spreader
Filled via between
top layer copper
and ground plane
Ground layer
Solder mask opening
for heat slug soldering
(not shown for other
soldering locations)
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
8
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
Application Information – Front Side Bus
The above diagram shows the CM3109 connected to the
Intel 865 GMCH Front Side Bus VTT pin GMCHVCCP.
The Enable signal GMCH_EN is used to shut down the
output of the CM3109 to save power during shutdown
periods. The VDDQSEL input ensures that the CM3109 is
in Front Side Bus mode, and the BOOTSEL from the
GMCH ensures the right Microprocessor VTT voltage is
applied.
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
9
PRELIMINARY
CM3109
CALIFORNIA MICRO DEVICES
SOIC-8 or PSOP-8 Package Dimensions
© 2003 California Micro Devices Corp. All rights reserved.
09/10/03
430 N. McCarthy BLVD, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
10