FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller
January 2007
FAN5033
8-Bit Programmable, 2- to 3-Phase, Synchronous Buck Controller
Features
Selectable 2- or 3-phase operation at up to 1MHz
per phase
±7.7mV worst-case differential sensing error over
temperature
Active current balancing between the output phases
Power Good and Crowbar blanking supports
on-the-fly VID code changes
0.5V to 1.6V output
Fully compliant with the Intel
®
VR10 and VR11
specifications
Selectable VR10 extended (7-bit) and VR11 (8-bit)
VID tables
Programmable soft-start ramp
Programmable short-circuit protection and
latch-off delay
Description
The FAN5033 device is a multi-phase buck switching
regulator controller optimized to convert a 12V input
supply to the processor core voltage required by high
®
performance Intel processors. It has an internal 8-bit
DAC that converts a digital voltage identification (VID)
code, sent from the processor, to set the output voltage
between 0.5V and 1.6V in 6.25mV steps. It outputs
PWM signals to external MOSFET drivers that drive the
switching power MOSFETs. The switching frequency of
the design is programmable by a single resistor value.
The number of phases can be programmed to support
two- or three-phase applications.
The FAN5033 also includes programmable no-load
offset and droop functions to adjust the output voltage
as a function of the load current, as required by the Intel
specifications. The FAN5033 provides an accurate and
reliable short-circuit protection function with an
adjustable over-current set point.
The FAN5033 is specified over the commercial
temperature range of 0°C to +85°C and is available in a
32-lead MLP package.
Applications
Desktop PC/Server processor power supplies for
existing and next-generation Intel processors
VRM modules
Ordering Information
Part Number
FAN5033MPX
Temperature Range
0°C to 85°C
Pb-Free
Yes
Package Type
MLP-32
Packing Method
Tape and Reel
Quantity
3,000 per Reel
Intel is a registered trademark of Intel Corporation.
®
© 2007 Fairchild Semiconductor 2006
FAN5033 Rev. 1.0.0
www.fairchildsemi.com
FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller
Block Diagram
VCC
RT
RAM PADJ
FAN5033
UVLO
SHUTDOWN
& BIAS
GND
OSCILL ATOR
SET EN
RESE T
PWM1
OD
+
–
CMP
Threshold
EN
–
+
+
CURREN T
BALANCING
CIRCUI T
–
+
–
+
–
CMP
RESE T
PWM2
DAC+OV P
CSREF
CMP
RESE T
PWM3
+
DAC - UV P
2 / 3 - PHASE
DRIVER LOGIC
–
PWRGD
DEL AY
CROWBAR
CURREN T
LIMIT
SW1
SW2
SW3
NC
CSCOM P
ILIMI T
DEL AY
CURREN T
LIMIT
CIRCUI T
+
–
CSREF
CSSUM
Z
+
COM P
–
PRECISION
REFERENCE
FBRTN
START-UP
CONTRO L
+
–
–
FB
+
Boot Control
VID
DAC
VIDSE L
DAC
BUFF
SS
VID7
VID6
VID5
VID4
VID3
VID2
VID1
VID0
Figure 1: Block Diagram
© 2007 Fairchild Semiconductor 2006
FAN5033 Rev. 1.0.0
www.fairchildsemi.com
2 of 39
FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller
Pin Assignment
Figure 2: Pin Assignment
Pin Definitions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
Name
EN
PWRGD
FBRTN
FB
COMP
SS
DELAY
ILIMIT
RT
RAMPADJ
CSREF
CSSUM
CSCOMP
Description
Power Supply Enable Input.
Analog comparator input with hysteresis. If input voltage
is higher than the internal threshold, the controller is enabled. If lower, the controller is
disabled.
Power Good Output.
Open drain output that pulls to GND when the output voltage is
outside the proper operating range.
Feedback Return.
VID DAC and Error Amplifier reference for remote sensing of output
voltage.
Feedback Input.
Error amplifier input for remote sensing of output voltage. A positive
internal current source is connected to this pin to allow the output voltage to be offset
lower than the DAC voltage.
Error Amplifier Output.
For loop compensation.
Soft-Start Input.
An external capacitor connected between this pin and GND sets the
soft-start ramp-up time.
Delay Timer Input.
An external capacitor connected between this pin and GND sets the
over-current latch-off delay time, BOOT voltage hold time, EN delay time, and PWRGD
delay time.
Current Limit Set.
An external resistor from this pin to GND sets the current limit
threshold of the converter.
Frequency Set Input.
An external resistor connected between this pin and GND sets
the oscillator frequency of the device.
PWM Ramp Set Input.
An external resistor connected between this pin and the
converter input voltage sets the internal PWM ramp.
Current Sense Amplifier Positive Input.
The voltage on this pin is used as the
reference for the current sense amplifier. The Power Good and Crowbar functions are
also internally connected to this pin.
Current Sense Amplifier Negative Input.
Current Sense Amplifier Compensation Output.
© 2006 Fairchild Semiconductor 2006
FAN5033 Rev. 1.0.0
www.fairchildsemi.com
3 of 39
FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller
Pin #
14
15
16
17 to 19
Name
GND
OD
NC
SW3 to
SW1
PWM3 to
PWM1
VCC
VID7 to
VID0
VIDSEL
Exposed
Paddle
Description
Ground.
All internal biasing and logic output signals of the device are referenced to this
ground.
Output Disable.
This pin is actively pulled low when the EN input is low or when V
CC
is
below its UVLO threshold to disable the external MOSFET drivers. (Also referred to as
OD# in the text of this document.)
No Connection.
This pin is not connected internally.
Switching Node Current Balance Inputs.
Sense the switching side of the inductor and
used to measure the current level in each phase. The SW pins of unused phases should
be left open.
PWM Outputs.
Each output is connected to the input of an external MOSFET driver,
such as the FAN5109. Connecting the PWM3 output to VCC disables that phase,
allowing the FAN5033 to operate as a two-phase controller.
Supply Voltage for the Device.
Voltage Identification Code Inputs.
These digital inputs are connected to the internal
DAC and used to program the output voltage. These pins have 1µA internal pull-down;
so if they are left open, the input state is decoded as logic low.
VID Table Select Input.
A logic low selects the extended VR10 DAC table and a logic
high selects the VR11 DAC table. This pin has a 1µA internal pull-down; so if left open,
the input state is decoded as logic low.
Internally connected to die ground.
May be connected to ground or left floating.
Connect to ground for lowest package thermal resistance.
20 to 22
23
24 to 31
32
-
© 2006 Fairchild Semiconductor 2006
FAN5033 Rev. 1.0.0
www.fairchildsemi.com
4 of 39
FAN5033 — 8-Bit Programmable 2- to 3-Phase Synchronous Buck Controller
Absolute Maximum Rating
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability.
The absolute maximum ratings are stress ratings only.
Unless otherwise specified, all other voltages are referenced to GND.
Symbol
V
CC
Supply Voltage
FBRTN
RAMPADJ, PWM3
SW1 – SW3
Parameter
Min.
-0.3
-0.3
-0.3
-10
-0.3
0
-65
Typ.
Max.
+15
+0.3
V
CC
+ 0.3
+25
+5.5
+125
+150
300
260
45
Unit
V
V
V
V
V
°C
°C
°C
°C
°C/W
All Other Inputs and Outputs
T
J
T
STG
T
L
T
LI
θ
JA
Operating Junction Temperature
Storage Temperature
Lead Soldering Temperature (10 seconds)
Lead Infrared Temperature (15 seconds)
Thermal Resistance Junction-to-Ambient
(1)
Note:
1. Junction-to-ambient thermal resistance,
θ
JA
, is a strong function of PCB material, board thickness, thickness and
number of copper planes, number of via used, diameter of via used, available copper surface, and attached heat
sink characteristics.
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to absolute maximum ratings.
Symbol
V
CC
T
A
Ambient Temperature
Parameter
Supply Voltage, VCC to GND
Min.
9.6
0
Typ.
12
Max.
14.4
+85
Unit
V
°C
© 2006 Fairchild Semiconductor 2006
FAN5033 Rev. 1.0.0
www.fairchildsemi.com
5 of 39
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