LX1676
P
RELIMINARY
D
ATA
S
HEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
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Mobile AMD Athlon
TM
VRM Controller
I N T E G R A T E D P R O D U C T S
Copyright
2000
Revision: 0.4b, 9/14/2004
D E S C R I P T I O N
The LX1676 is a highly integrated
VRM power supply controller IC
featuring two PWM switching
regulator stages.
The two constant frequency
voltage-mode PWM phases are
configured as a single biphase high
current output core supply.
In biphase operation, the high
current (>25A) output is generated by
a LoadSHARE
TM
technique that
balances the currents in the two
phases. Power loss and noise, due to
the ESR of the input capacitors, are
minimized by operating the PWMs
180 out of phase.
A synchronized Transient
Correction Loop provides except-
ional control of the output droop and
overshoot during very high di/dt load
changes, the circuit can be configured
for droop only, overshoot only or
both.
This architecture also minimizes
capacitor requirements while
maximizing regulator response.
A true differential input amplifier is
used for remote voltage sensing at the
processor core.
A VID code generator provides an
internal reference that will set the
output voltage. This VID code can be
changed during operation and the
reference will slew the output voltage to
its new setting at a preset rate. During
VID changes on the fly the Power Good
indication will stay valid.
Current through the lower phase 1
MOSFET will be sampled using its
R
DS(ON)
for current limit and shut
down.
For further protection, an over
voltage circuit will trip at a specified
setting and clamp the output by turning
off the upper MOSFETs and turning on
the lower MOSFETs.
The upper MOSFET drivers will use
a bootstrap capacitor to provide the
upper drive voltage over the input
voltage range of 6 to 24 volts.
IMPORTANT:
For the most current data, consult
MICROSEMI
's website:
http://www.microsemi.com
Patent numbers US6292378,US6285571,US6356063, US6605931
K E Y F E A T U R E S
High Current Biphase
Operation
Outputs As Low As 0.925V
Biphase LoadSHARE
TM
Transient Correction Loop
Reduces Required
Capacitance
Differential Amplifier For
Remote Voltage Sensing
Integrated High Current
MOSFET Drivers
200KHz to 1MHz Frequency
Operation
Programmable Slew Rate
Control For Start-Up Sequence
and VID change
VID Changes On The Fly
Power Good Indicator
Short Circuit Protection
Output Over Voltage and
Under Voltage Protection
No current-sense resistors
A P P L I C A T I O N S
AMD Mobile Athlon
TM
or
Duron
TM
Processor Core
Voltage Supply
Voltage Regulator Modules
P R O D U C T H I G H L I G H T
L X 1 6 7 6
5 B i t V I D
7 0 n H
T r a n s i e n t C o r r e c t i o n L o o p
V i n 6 t o 2 4 V
V i n 6 t o 2 4 V
V o u t
V i n + 5 V
P A C K A G E O R D E R I N F O
T
J
(C)
PW
Plastic TSSOP
38-Pin
LQ
Plastic
MLPQ
38-Pin
0 to 70
LX1676-CPW
LX1676-CLQ
Note: Available in Tape & Reel.
Append the letters "TR" to the part number.
(i.e. LX1676-CLQTR)
L
L
X
X
1
1
6
6
7
7
6
6
LX1676
P
RELIMINARY
D
ATA
S
HEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
WWW
.
Microse
m
i
.
CO
M
Mobile AMD Athlon
TM
VRM Controller
I N T E G R A T E D P R O D U C T S
Copyright
2000
Revision: 0.4b, 9/14/2004
A B S O L U T E M A X I M U M R A T I N G S
Supply Input Voltage (VCCL, VCC)................................................-0.3V to 6.0V
Battery Input Voltage (VIN)..............................................................-0.3V to 36V
Current Limit Sense (ILIM1, ILIM3) ................................................-0.3V to 36V
Topside Driver Supply Input Voltage (VC1, VC2, VC3)........-0.3 toVSx + 6.0V
Topside Driver Return Input Voltage (VS1, VS2)................................-5V to 36V
Differential Sense Input Voltage (FB+, FB-)....................................-0.3V to 6.0V
VID0 VID4, Input Voltage ...............................................................-0.3V to 6V
High Side Driver Peak (<500ns) Current (HO1/2, I-MAX) ............................+1A
Low Side Driver Peak (<500ns) Sink Current (LO1/2, I-MIN)....................+1.5A
Operating Junction Temperature.................................................................. 150C
Storage Temperature Range...........................................................-65C to 150C
Lead Temperature (Soldering 10 seconds) .................................................. 300C
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal
.
x denotes
respective pin designator 1, 2, or 3
P A C K A G E P I N O U T
1
2
3
4
5
6
7
8
9
10
11
12 13 14 15 16 17 18 19 20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
FB-
DFOUT
EO1
EA1-
DACOUT
PWGD
GND
ROSC
ENA
VID4
VID3
PGN3
I-MIN
VCCL
LO2
PGN
LO1
VS1
HO1
VC1
VC3
I-MAX
IL
IM
3
IL
IM
1
LP
1
LP
2
EA2-
EO
2
FB+
VI
D
2
VI
D
1
VI
D
0
VS2
HO
2
VC
2
VCC
VIN
VS3
Connect Bottom to
Power GND
LQ
P
ACKAGE
(Top View)
1
19
38
20
FB-
DFOUT
EO1
EA1-
DACOUT
PWGD
GND
VIN
ROSC
ENA
VID4
VID3
VID2
VID1
VID0
VS2
H02
VC2
VCC
PGN3
I-MIN
VCCL
LO2
PGN
LO1
VC1
VC3
VS3
ILIM3
ILIM1
LP1
LP2
EA2-
EO2
FB+
VS1
HO1
I-MAX
PW
P
ACKAGE
(Top View)
R E C O M M E N D E D O P E R A T I N G C O N D I T I O N S
LX1676
Parameter
Symbol
Min Typ Max
Units
IC Input Supply Voltage
VCC
4.5
5.5
V
Battery Input Voltage
VIN
5.7
25.2
V
Biphase Topside Driver Return Voltage
VS1, VS2
0
25.2
V
Transient Correction Phase Driver Return Voltage
VS3
0
5.5
V
P
P
A
A
C
C
K
K
A
A
G
G
E
E
D
D
A
A
T
T
A
A
LX1676
P
RELIMINARY
D
ATA
S
HEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
WWW
.
Microse
m
i
.
CO
M
Mobile AMD Athlon
TM
VRM Controller
I N T E G R A T E D P R O D U C T S
Copyright
2000
Revision: 0.4b, 9/14/2004
F U N C T I O N A L P I N D E S C R I P T I O N
Name Description
FB+
Differential Amplifier Positive Input Feedback from output
FB-
Differential Amplifier Negative Input Feedback from output
DFOUT
Differential Amplifier Output
EA1-
Phase 1 Error Amplifier Negative Input
EO1
Phase 1 Error Amplifier Output
GND Analog
Ground
ROSC
A resister to ground sets PWM frequency
ENA
Enable Input Logic Low disables all converter phases
DACOUT
DAC Output voltage 50uA bi-directional current source
VID4
Digital Input for VID code Has an internal pull-up resister
VID3
Digital Input for VID code Has an internal pull-up resister
VID2
Digital Input for VID code Has an internal pull-up resister
VID1
Digital Input for VID code Has an internal pull-up resister
VID0
Digital Input for VID code Has an internal pull-up resister
PWGD
Power Good Output Pin Open drain output pin for power good indication. High = Power Good
VCC
IC Supply Voltage. Nominal +5V
VC3
Supply for transient correction phase upper MOSFET driver, bootstrap voltage
PGN3
Power ground pin for Transient Correction Loop driver
I-MIN
Output Driver for lower Transient Correction Loop MOSFET
VS3
Low side of upper driver for Transient Correction Loop MOSFET Driver power return
I-MAX
Output Driver for upper Transient Correction Loop MOSFET
ILIM3
Transient Correction Loop current sense A resister sets an upper limit for over current detection and shut down.
LP1
Phase 2 differential amplifier positive input, filtered feedback from phase 1 output
EA2-
Negative Input of phase 2 integrating amplifier
EO2
Output of phase 2 integrating amplifier
LP2
Phase 2 differential amplifier negative input, filtered feedback from phase 2 output
VIN
Battery Voltage Input.
LO2
Driver Output for phase 2 lower MOSFET
VS2
Low side of upper gate driver for phase 2.
HO2
Driver Output for phase 2 upper MOSFET
VC2
Supply for phase 2 upper MOSFET driver, bootstrap voltage
PGN
Power ground pin for current sensing of lower MOSFET R
DS(ON)
for phase 1.
LO1
Driver Output for phase 1 lower MOSFET
ILIM1
Over-Current Limit Set A resister sets an upper limit for over current detection and shut down.
VS1
Low side of upper gate driver for phase #1.
HO1
Driver Output for phase 1 upper MOSFET
VC1
Supply for phase 1 upper MOSFET driver, bootstrap voltage
VCCL
Voltage bus for the lower MOSFET drivers. Nominal +5V
P
P
A
A
C
C
K
K
A
A
G
G
E
E
D
D
A
A
T
T
A
A
LX1676
P
RELIMINARY
D
ATA
S
HEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
WWW
.
Microse
m
i
.
CO
M
Mobile AMD Athlon
TM
VRM Controller
I N T E G R A T E D P R O D U C T S
Copyright
2000
Revision: 0.4b, 9/14/2004
E L E C T R I C A L C H A R A C T E R I S T I C S
Unless otherwise specified, the following specifications apply over the operating ambient temperature 0C
T
A
70C except where
otherwise noted and the following test conditions: VCC = 5V, VCCL = 5V, VIN = 12V, Switching Frequency = 500KHz.
LX1676
Parameter Symbol
Test
Conditions
Min Typ Max
Units
REGULATOR
ENA = VCC, FB+ = FB-
1
5
9
mA
IC Supply Current
I
Q(VCC)
ENA = GND
1
A
Low Side Driver Operating
Current
I
Q(VCCL)
ENA = VCC, FB+ = FB-
0.5
1
mA
High Side Driver Operating
Current
I
Q(VCx)
ENA = VCC, FB+ = FB-
2
4
mA
ERROR AMPLIFIER: PHASE 1
Input Offset Voltage
V
OS
Common Mode Voltage (V
CM
) = 1.4V
-6
6
mV
Input Bias Current
I
EA1
-100
100
nA
DC Open Loop Gain
60
70
dB
Input Common Mode Range
V
ICM
CMRR > 50dB
0.8
2.5
V
V
EO1(MAX)
I
EA1
= 2mA
4.0
Output Voltage Swing
V
EO1(MIN)
I
EA1
= -20uA
0.15
0.5
V
Unity Gain Bandwidth
UGBW
20
MHz
DIFFERENTIAL AMPLIFIER
Input Offset Voltage
V
OS
V
CM
=1.4V -6
6
mV
Gain
A
DA
0.99 1 1.01 V/V
Common Mode Rejection Ratio
CMRR
DA
0.8V < V
CM
< 2.5V
65
dB
Input
Resistance
R
IN
Measured at FB+ Input
30
K
Input Common Mode Range
V
CM
0
3
V
Source / Sink Current
V
DFOUT
= 0V
5
mA
V
DFOUT(MAX)
I
DFOUT
= 2mA
4.0
Output Voltage Swing
V
DFOUT (MIN)
I
EA1
= -20uA
0.2
V
Unity Gain Bandwidth
UGBW
10
MHz
Slew
Rate
SR
5
V/
s
OSCILLATOR
Maximum Clock Frequency
f
MAX
R
PWM
=10k
0.9 1 1.1
MHz
Minimum Clock Frequency
f
MIN
R
PWM
=50k
180 200 220 KHz
Frequency Stability
4
%
PWM OUTPUT
During Transient Correction Switching
100
Maximum Duty Cycle
DC
MAX
Transient Correction Not Switching
40
50
%
Minimum Pulse Width
t
PWM(MIN)
3000pF
Load
60
nS
Dead Time
3000pF Load at 50% of VCCL
50
80
200
nS
VIN = 6V
0.70
VIN = 12
1.40
Ramp Amplitude
V
RAMP
VIN = 24 V
2.80
V
PHASE 2 INTEGRATING AMPLIFIER
Input Offset Voltage
V
OS
V
CM
=1.4V
-6
6
M V
DC Open Loop Gain
70
dB
V
EO2(MAX)
I
EA2
= 2mA
4.0
Output Voltage Swing
V
EO2(MIN)
I
EA2
= -20uA
0.15
0.5
V
Unity Gain Bandwidth
UGBW
20
MHz
E
E
L
L
E
E
C
C
T
T
R
R
I
I
C
C
A
A
L
L
S
S
LX1676
P
RELIMINARY
D
ATA
S
HEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
WWW
.
Microse
m
i
.
CO
M
Mobile AMD Athlon
TM
VRM Controller
I N T E G R A T E D P R O D U C T S
Copyright
2000
Revision: 0.4b, 9/14/2004
E L E C T R I C A L C H A R A C T E R I S T I C S ( C O N T I N U E D )
Unless otherwise specified, the following specifications apply over the operating ambient temperature 0C
T
A
70C except where
otherwise noted and the following test conditions: VCC = 5V, VCCL = 5V, VIN = 12V, Switching Frequency = 500KHz.
LX1676
Parameter Symbol
Test
Conditions
Min Typ Max
Units
PHASE 2 DIFFERENTIAL AMPLIFIER
Input Offset Voltage
V
OS
LP1=LP2 -6
6
mV
Gain
A
DA
0.98 1 1.02 V/V
Common Mode Rejection Ratio
CMRR
DA
Common Mode Voltage = 0 to 2 V
60
dB
Input
Resistance
R
B
180
K
Unity Gain Bandwidth
UGBW
4
MHz
TRANSIENT CONTROL LOOP
Voltage Droop Sense
Propagation Delay : FB+ and
FB- to I-MAX
50 nS
Voltage Overshoot Sense
Propagation Delay : FB+ and
FB- to I-MIN
50 nS
Voltage Droop Sense Threshold
V
DFOUT
Rising 3000pF Load
40
mV
Voltage Overshoot Sense
Threshold
V
DFOUT
Falling 3000pF Load
40
mV
OUTPUT DRIVERS
Driver
Rise
Time
Fall
Time
t
RISE
t
FALL
CL = 3000pF, VCx - VSx = 5V
50
50
nS
High Side Driver Voltage:
[V
HOx
- V
VSx
]
Drive
High
Drive
Low
V
HOx
= 20mA, VCx - VSx = 5.0 V
V
HOx
= -20mA, VCx - VSx = 5.0 V
4.8
4.9
0.1
0.2
V
Low Side Driver Voltage:
[V
LOx
V
PGN
]
Drive
High
Drive
Low
V
LOx
= 20mA, VCCL - VPGN = 5.0 V
V
LOx
= -20mA, VCCL - VPGN = 5.0 V
4.8
4.9
0.1
0.2
V
High Side Driver Current
I
HOx
VCx - VSx = 5.0 V, Load = 3300pf at
<500nSec
1 A
Lower MOSFET Driver Current
I
LOx
VCCL - PGN = 5.0 V, Load = 3300pf at
<500nSec
1.5 A
PHASE 1 OVER CURRENT PROTECTION
Current Sense Bias Current
I
ILIM1
44
50
60
A
Current Sense Delay
t
CSD(ILIM1)
200
400
500 nS
TRANSIENT CORRECTION LOOP OVER CURRENT PROTECTION
Current Sense Bias Current
I
ILIM3
40
50
60
A
Current Sense Delay
t
CSD(ILIM3)
200
400
500 nS
ENABLE INPUT / VOLTAGE IDENTIFICATION (VID)
Logic Low Threshold
1.5 V
Hysteresis
0.3 V
Pullup Resistance
100 K
POWER GOOD
Low Output Voltage
V
PWGD
I
PWGD
= -3mA
0.5
V
E
E
L
L
E
E
C
C
T
T
R
R
I
I
C
C
A
A
L
L
S
S
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