www.fairchildsemi.com
FAN5056MV85
High Performance Programmable Synchronous
DC-DC Controller for Multi-Voltage Platforms
Features
Description
• Output programmable in 25mV steps from 1.05V to
1.825V using a dynamically programmable integrated
5-bit DAC
• Controls adjustable linears for Vclock (2.5V),
Vnorthbridge (1.8V) or Vagp (selectable 1.5V/3.3V), and
Vadj (1.2V nominal)
• Remote sense
• Programmable Active Droop™ up to 200mV
• Drives N-Channel MOSFETs
• Overcurrent protection using MOSFET sensing
• Overvoltage protection including startup
• 85% efficiency typical at full load
• Integrated Power Good and Enable/Soft Start functions
• Meets Intel VRM8.5 specifications using minimum
number of external components
• 24 pin SOIC package
The FAN5056 is a synchronous mode DC-DC controller IC
which provides a highly accurate, programmable set of output
voltages for multi-voltage platforms such as the Intel Pentium III,
and provides a complete solution for all Intel VRM8.5 CPU
applications, and for other high-performance processors. The
FAN5056 features remote voltage sensing, independently
adjustable current limit, and a proprietary wide-range Programmable Active Droop™ for optimal converter transient
response and VRM8.5 compliance. The FAN5056 uses a 5-bit
D/A converter to dynamically program the output voltage during operation from 1.05V to 1.825V in 25mV steps. The
FAN5056 uses a high level of integration to deliver load currents in excess of 28A from a 5V source with minimal external circuitry. Synchronous-mode operation offers optimum
efficiency over the entire specified output voltage range. An
on-board precision low TC reference achieves 0.8% voltage
regulation without expensive external components. The
FAN5056 includes linear regulator controllers for Vclock
(2.5V),Vnorthbridge (1.8V) or Vagp (selectable 1.5V/3.3V),
and Vadjustable (1.2V nominal) each adjustable with an
external divider. The FAN5056 also offers integrated functions
Applications
• Power supply for Pentium® III Platforms
• VRM for Pentium III processor
• Programmable multi-output power supply
Block Diagram
+3.3V
+5V
VCCA 21
+1.2V/Adj
9
+
-
RD
PWRGD,
OCL
10
VCCP
11
19
+
REF
OCL
+
-
REF
+12V
PWRGD,
OCL
12
+2.5V
+
OSC
+5V
18
RS
20
24 VCCP
1 HIDRV
+
15
14
V
+
Digital
Control
+
2
23 LODRV
PWRGD, OCL
13
VCC
22
3.3/1.5V
GNDP
5-Bit
DAC
8 7 65 4
VID0 VID2 VID4
VID1 VID3
1.24V
Reference
Power
Good
3
GNDA
17
PWRGD
16
ENABLE/SS
Pentium is a registered trademark of Intel Corporation. Programmable Active Droop is a trademark of Fairchild Semiconductor.
REV. 1.0.9 9/4/01
PRODUCT SPECIFICATION
FAN5056MV85
Absolute Maximum Ratings
Supply Voltage VCCP to GND
15V
Supply Voltage VCCA to GND
13.5V
Voltage Identification Code Inputs, VID0-VID4
VCCA
All Other Pins
13.5V
Junction Temperature, TJ
150°C
Storage Temperature
-65 to 150°C
Lead Soldering Temperature, 10 seconds
300°C
Thermal Resistance Junction-to-case, Θ 1JA
75°C/W
Note 1: Component mounted on demo board in free air.
Recommended Operating Conditions
Parameter
Conditions
Min.
Typ.
Max.
Units
Supply Voltage VCCA
4.50
5
5.25
V
Input Logic HIGH
2.0
V
Input Logic LOW
0.8
Ambient Operating Temperature
70
0
Output Driver Supply, VCCP
10.8
12
V
°C
13.2
V
Electrical Specifications
(VCCA = 5V, VCCP = 12V, VOUT = 1.425V, and TA = +25°C using circuits in Figure 1, unless otherwise noted.)
The • denotes specifications which apply over the full operating temperature range.
Parameter
Conditions
Min.
Typ.
Max. Units
VCC Regulator
Output Voltage
See Table I
FAN5056MV85
•
1.05
Output Current
Output Temperature Drift
TA = 0 to 70°C, VVID = 1.425V
Line Regulation
VIN = 4.75V to 5.25V
A
1.453 1.465 1.477
V
•
-6
mV
•
+10
mV/V
ILOAD = 0.8A, VVID = 1.425V
Impedance3
ILOAD = 0.8A to 30A
Maximum Programmable Droop
Output Ripple
13.0
•
Transient2
14.4
15.8
200
20MHz BW, ILOAD = 28A
Total Output Variation, Steady State1 VVID = 1.425V3
Total Output Variation,
V
28
Initial Voltage Setpoint
Internal Droop
1.825
KΩ
mV
20
mVpk
Short Circuit Detect Current
1.360
1.490
V
•
1.335
1.515
V
•
ILOAD = 0.8A to Imax, VVID = 1.425V
•
45
60
µA
50
Efficiency
ILOAD = 18A, VVID = 1.425V
83
%
Output Driver Rise & Fall Time
See Figure 3
50
nsec
Output Driver Deadtime
See Figure 3
50
nsec
Duty Cycle
0
100
%
V
5V UVLO
•
3.76
4
4.24
12V UVLO
•
7.65
8.5
9.35
V
17
µA
Soft Start Current
REV. 1.0.9 9/4/01
5
3