• Programmable output from 1.10V to 1.85V in 25mV steps
using an integrated 5-bit DAC
• Two interleaved synchronous slices for maximum
performance
• 100nsec response time
• Built-in current sharing between slices
• Remote sense
• Programmable Active Droop
(Voltage Positioning)
• Programmable frequency from 200KHz to 2MHz
• Adaptive delay gate switching
• Integrated high-current gate drivers
• Integrated Power Good, OV, UV, Enable/Soft Start
functions
• Drives N-channel MOSFETs
• Operation optimized for 5V operation
• High efficiency mode (E*) at light load
• Overcurrent protection using MOSFET sensing
• 24 pin TSSOP package
Description
The FAN5091 is a synchronous multi-slice DC-DC controller
IC which provides a highly accurate, programmable output
voltage for all high-performance processors. Two interleaved
synchronous buck regulator slices with built-in current shar-
ing operate 180° out of phase to provide the fast transient
response needed to satisfy high current applications while
minimizing external components. The FAN5091 features
remote voltage sensing and Programmable Active Droop
for 100nsec converter transient response with minimum out-
put capacitance. It has integrated high-current gate drivers,
with adaptive delay gate switching, eliminating the need for
external drive devices. The FAN5091 uses a 5-bit D/A con-
verter to program the output voltage from 1.10V to 1.85V in
25mV steps with an accuracy of 1%. The FAN5091 uses a
high level of integration to deliver load currents in excess of
50A from a 5V source with minimal external circuitry. The
FAN5091 also offers integrated functions including Power
Good, Output Enable/Soft Start, under- voltage lockout,
over-voltage protection, and adjustable current limiting with
independent current sense on each slice. It is available in a
24 pin TSSOP package.
Applications
•
•
•
•
Power supply for Pentium
IV
Power supply for Athlon
VRM for Pentium IV processor
Programmable step-down power supply
Block Diagram
Bypass
6
5V Reg
+12V
18
+12V
13
23
+5V
OSC
14
+
-
Digital
Control
15
+12V
17
16
VO
+12V
12
11
+5V
-
+
-
+
-
+
-
+
Digital
Control
10
+12V
8
9
5-Bit
DAC
1 2 3 4
5
24
Power
Good
19
PWRGD
21
7
22
ENABLE/SS
20
ILIM
VID0 VID2 VID4
VID1 VID3
DROOP/E* GNDA
Pentium is a registered trademark of Intel Corporation. Athlon is a registered trademark of AMD. Programmable Active Droop is a trademark of Fairchild Semiconductor.
REV. 1.0.0 5/10/01
FAN5091
PRODUCT SPECIFICATION
Pin Assignments
VID0
VID1
VID2
VID3
VID4
BYPASS
AGND
LDRVB
PGNDB
SWB
HDRVB
BOOTB
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
VFB
RT
ENABLE/SS
DROOP/E*
ILIM
PWRGD
VCC
LDRVA
PGNDA
SWA
HDRVA
BOOTA
FAN5091
Pin Definitions
Pin Number
1-5
Pin Name
VID0-4
Pin Function Description
Voltage Identification Code Inputs.
These open collector/TTL compatible
inputs will program the output voltage over the ranges specified in Table 1.
Pull-ups are internal to the controller.
5V Rail.
Bypass this pin with a 1
µ
F ceramic capacitor to AGND.
Analog Ground.
Return path for low power analog circuitry. This pin should be
connected to a low impedance system ground plane to minimize ground loops.
Low Side FET Driver for B.
Connect this pin to the gate of an N-channel
MOSFET for synchronous operation. The trace from this pin to the MOSFET gate
should be <0.5
"
.
Power Ground B.
Return pin for high currents flowing in low-side MOSFET.
Connect directly to low-side MOSFET source.
High side driver source and low side driver drain switching node B.
Gate
drive return for high side MOSFET, and negative input for low-side MOSFET
current sense.
High Side FET Driver B.
Connect this pin to the gate of an N-channel MOSFET.
The trace from this pin to the MOSFET gate should be <0.5
"
.
Bootstrap B.
Input supply for high-side MOSFET.
Bootstrap A.
Input supply for high-side MOSFET.
High Side FET Driver A.
Connect this pin to the gate of an N-channel MOSFET.
The trace from this pin to the MOSFET gate should be <0.5
"
.
High side driver source and low side driver drain switching node A.
Gate
drive return for high side MOSFET, and negative input for low-side MOSFET
current sense.
Power Ground A.
Return pin for high currents flowing in low-side MOSFET.
Connect directly to low-side MOSFET source.
Low Side FET Driver for A.
Connect this pin to the gate of an N-channel
MOSFET for synchronous operation. The trace from this pin to the MOSFET gate
should be <0.5
"
.
VCC.
Internal IC supply. Connect to system 12V supply, and decouple with a
0.1
µ
F ceramic capacitor.
Power Good Flag.
An open collector output that will be logic LOW if the output
voltage is not within +10/-15% of the nominal output voltage setpoint.
6
7
8
BYPASS
AGND
LDRVB
9
10
PGNDB
SWB
11
12
13
14
15
HDRVB
BOOTB
BOOTA
HDRVA
SWA
16
17
PGNDA
LDRVA
18
19
VCC
PWRGD
2
REV. 1.0.0 5/10/01
PRODUCT SPECIFICATION
FAN5091
Pin Number
20
21
Pin Name
ILIM
DROOP/E*
Pin Function Description
Current Limit.
A resistor from this pin to ground sets the over current trip level.
Droop Control/Energy Star Mode Control.
A resistor from this pin to ground
sets the amount of droop by controlling the gain of the current sense amplifier.
When this pin is pulled high to BYPASS, the slice A drivers are turned off for
Energy-star operation.
Output Enable/Softstart.
A logic LOW on this pin will disable the output. An
internal current source allows for open collector control. This pin also doubles as
soft start.
Frequency Set.
A resistor from this pin to ground sets the switching frequency.
Voltage Feedback.
Connect to the desired regulation point at the output of the
converter.
22
ENABLE/SS
23
24
RT
VFB
Absolute Maximum Ratings
Parameter
Supply Voltage VCC
Supply Voltages BOOTA, BOOTB
Voltage Identification Code Inputs, VID0-VID4
VFB, ENABLE/SS, PWRGD, DROOP/E*
SWA, SWB
PGNDA, PGNDB to AGND
Gate Drive Current, peak pulse
Junction Temperature, T
J
Storage Temperature
Lead Soldering Temperature, 10 seconds
Power Dissipation, P
D
Thermal Resistance Junction-to-Case,
Θ
JC
-55
-65
300
950
13
-3
-0.5
3
150
150
Min.
Typ.
Max.
15
18
6
6
15
0.5
Unit
V
V
V
V
V
V
A
°
C
°
C
°
C
mW
°
C/W
Recommended Operating Conditions
Parameter
Output Driver Supply, BOOT
Input Logic HIGH
Input Logic LOW
Ambient Operating Temperature
0
Conditions
Min.
10.8
2.4
0.8
70
Typ.
12
Max.
13.2
Units
V
V
V
°
C
REV. 1.0.0 5/10/01
3
FAN5091
PRODUCT SPECIFICATION
Electrical Specifications
(V
CC
= 12V,V
OUT
= 1.500V, and T
A
= +25°C using circuit in Figure 1, unless otherwise noted.)
The
•
denotes specifications which apply over the full operating temperature range.
Parameter
Output Voltage
Output Current
Initial Voltage Setpoint
Output Temperature Drift
Line Regulation
Droop
3
Programmable Droop Range
Total Output Variation,
Steady State
1
Response Time
Gate Drive On-Resistance
Upper Drive Low Voltage
Upper Drive High Voltage
Lower Drive Low Voltage
Lower Drive High Voltage
Output Driver Rise & Fall Time
Current Mismatch
Output Overvoltage Detect
Efficiency
Oscillator Frequency
Oscillator Range
Maximum Duty Cycle
Minimum LDRV on-time
Input LOW current, VID pins
Soft Start Current
Enable Threshold
BYPASS Voltage
BYPASS Capacitor
PWRGD Threshold
PWRGD Hysteresis
PWRGD Output Voltage
PWRGD Delay
12V UVLO
UVLO Hysteresis
12V Supply Current
Over Temperature Shutdown
Over Temperature Hysteresis
4
HDRV and LDRV Open
I
sink
= 4mA
High
→
Low
•
8.5
500
9.5
0.5
20
150
40
10.5
Logic LOW, minimum
Logic LOW, maximum
•
•
ON
OFF
0.4
4.75
100
81
106
85
110
20
0.4
89
114
5
5.25
V
nF
%V
out
mV
V
µsec
V
V
mA
°C
°C
REV. 1.0.0 5/10/01
Conditions
See Table 1
I
LOAD
= 5A
T
A
= 0 to 70°C
V
CC
= 11.4V to 12.6V
I
LOAD
= 0.8A to I
max
I
LOAD
= 0.8A to I
max
•
•
•
•
Min.
1.100
Typ.
50
Max.
1.850
Units
V
A
V
mV
µV
1.485
1.500
+5
+130
1.515
-90
-10
1.430
1.430
-100
-110
0
1.570
1.570
mV
%Vout
V
V
nsec
Ω
V
V
V
V
nsec
%
Total Output Variation, Transient
2
I
LOAD
= 0.8A to I
max
∆
V
out
= 10mV
V
HDRV
–V
SW
at I
sink
= 10µA
V
BOOT
–V
HDRV
at I
source
= 10µA
I
sink
= 10µA
V
CC
–V
LDRV
at I
source
= 10µA
See Figure 3
R
DS,on
(A) = R
DS,on
(B), I
LOAD
= I
max
100
1.0
0.2
0.5
0.2
0.5
20
5
•
2.1
85
70
•
450
200
90
330
50
10
1.0
600
750
2000
2.3
V
%
KHz
KHz
%
nsec
µA
µA
V
I
LOAD
= I
max
I
LOAD
= 2A (E*-mode)
RT = 41.2K
Ω
RT = 125K
Ω
to 12.5 K
Ω
RT = 125K
Ω
RT = 12.5K
Ω
V
VID
= 0.4V
PRODUCT SPECIFICATION
FAN5091
Notes:
1. Steady State Voltage Regulation includes Initial Voltage Setpoint, Output Ripple and Output Temperature Drift and is
measured at the converter’s VFB sense point.
2. As measured at the converter’s VFB sense point. For motherboard applications, the PCB layout should exhibit no more than
0.5m
Ω
trace resistance between the converter’s output capacitors and the CPU. Remote sensing should be used for optimal
performance.
3. Using the VFB pin for remote sensing of the converter’s output at the load, the converter will be in compliance with Intel’s
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