Provides Single Chip Solution for Vcore,
GTL+ ,AGP Bus, and 1.8V
Automatic Voltage Selection for AGP slot
Vddq supply
Linear regulator controller on board for 1.8V
Designed to meet Intel Latest VRM specification for next generation micrprocessors
On board DAC programs the output voltage
from 1.3V to 3.5V
Linear regulator controller on board for 1.5V
GTL+ supply
Loss less Short Circuit Protection for all
outputs
Synchronous operation allows maximum
efficiency
Patented architecture allows fixed frequency
operation as well as 100% duty cycle during
dynamic load
Minimum part count
Soft Start
High current totem pole driver for direct
driving of the external Power MOSFET
Power Good function Monitors all Outputs
OVP Circuitry Protects the Switcher Output
and generates a Fault output
APPLICATIONSAPPLICATIONS
Total Power Soloution for Next Generation Intel
Processor application
US3021M
PLUS TRIPPLE LDO CONTROLLER
PRELIMINARY DATASHEET
DESCRIPTIONDESCRIPTION
The US3021M controller IC is specifically designed to
meet Intel specification for next generation microprocessor applications requiring multiple on board regulators . The US3021M provides a single chip control-
ler IC for the Vcore , 3LDO controllers, one with the
automatic select pin that connects to the TYPE DETECT pin of the AGP slot for the AGP Vddq supply,
one for GTL+ and the other for the 1.8V chip set
regulator as required for the next generation PC
applications. The US3021M uses N ch MOSFET as
pass transistor for Vout2(Vddq), Vout3(1.5V) and
Vout4(1.8V). No external resistor divider is necessary for any of the regulators. The switching regulator
feature a patented topology that in combination with a
few external components as shown in the typical application circuit ,will provide well in excess of 20A of output current for an on- board DC/DC converter while automatically providing the right output voltage via the 5 bit
internal DAC .The US3021M also features, loss less cur-
rent sensing for both switcher by using the Rds-on
of the high side Power MOSFET as the sensing resistor, an output under voltage shutdown that detects short circuit condition for the linear outputs
and latches the system off, and a Power Good win-
dow comparator that switches its open collector output
low when any one of the outputs is outside of a pre programmed window.
TYPICAL APPLICATIONTYPICAL APPLICATION
5V
3.3V
Vout2
Vout3
LINEAR
CONTROL
US3021M
LINEAR
CONTROL
PACKAGE ORDER INFORMATIONPACKAGE ORDER INFORMATION
Ta (°C) Device Package
0 TO 70 US3021MCW 28 pin Plastic SOIC WB
Rev. 1.3
12/8/00
SWITCHER
CONTROL
LINEAR
CONTROL
3021Mapp3-1.1
Vout1
Vout4
4-1
Page 2
US3021M
ABSOLUTE MAXIMUM RATINGSABSOLUTE MAXIMUM RATINGS
V5 supply Voltage ........................................... 7V
V12 Supply Voltage ............................................ 20V
Storage Temperature Range ................................. -65 TO 150°C
Operating Junction Temperature Range .......... 0 TO 125°C
Unless otherwise specified ,these specifications apply over ,V12 = 12V, V5 = 5V and Ta=0 to 70°C. Typical values
refer to Ta =25°C. Low duty cycle pulse testing are used which keeps junction and case temperatures equal to the
ambient temperature.
Switching Controllers; Vcore (Vsen 1) and AGP (Vsen 2)
VID Section (Vcore only)
DAC output voltage (note 1)0.99VsVs1.01VsV
DAC Output Line Regulation0.1%
DAC Output Temp Variation0.5%
VID Input LO0.8V
VID Input HI2V
VID input internal pull-up
resistor to V527kΩ
Vsen2 VoltageSelect<0.8V1.5V
Select>2V3.3V
4-2
Rev. 1.3
12/8/00
Page 3
US3021M
Error Comparator Section
Input bias current2uA
Input Offset Voltage-2+2mV
Delay to OutputVdiff=10mV100nS
LSB input to the DAC that programs the output voltage. This pin is TTL compatible that
realizes a logic “1” as either HI or Open. When left open,his pin is pulled up internally by
a 27kΩ resistor to 5V supply.
Input to the DAC that programs the output voltage. This pin is TTL compatible that realizes a logic “1” as either HI or Open. When left open,his pin is pulled up internally by a
27kΩ resistor to 5V supply.
Input to the DAC that programs the output voltage. This pin is TTL compatible that realizes a logic “1” as either HI or Open. When left open,his pin is pulled up internally by a
27kΩ resistor to 5V supply.
MSB input to the DAC that programs the output voltage. This pin is TTL compatible that
realizes a logic “1” as either HI or Open. When left open,his pin is pulled up internally by
a 27kΩ resistor to 5V supply.
This pin selects a range of output voltages for the DAC.When in the LOW state the range
is 1.3V to 2.05V and when it switches to HI state the range is 2.0V to 3.5V. This pin is
TTL compatible that realizes a logic “1” as either HI or Open. When left open,his pin is
pulled up internally by a 27kΩ resistor to 5V supply.
This pin is an open collector output that switches LO when any of the outputs are outside
of the specified under voltage trip point. It also switches low when Vsen1 pin is more than
10% above the DAC voltage setting.
This pin provides the feedback for the synchronous switching regulator. Typically this pin
can be connected directly to the output of the switching regulator. However, a resistor
divider is recommended to be connected from this pin to vout1 and GND to adjust the
output voltage for any drop in the output voltage that is caused by the trace resistance.
The value of the resistor connected from Vout1 to FB1 must be less than 1000Ω.
This pin controls the gate of an external MOSFET for the AGP linear regulator.
This pin provides shutdown for all the regulatos. A TTL compatible, logic level high applied
to this pin disables all the outputs and discharges the soft start capacitor. The SD signal
turns off the synchronous allowing body diode to conduct and discharge the output cap.
4-4
Rev. 1.3
12/8/00
Page 5
US3021M
PIN# PIN SYMBOL
22Vsen1
10Vsen2
15Drive4
23OCSET
26PHASE
12SS
13FAULT/Rt
18Drive3
19Vsen3
16NC
Pin Description
This pin is internally connected to the undervoltage and overvoltage comparators sensing
the Vcore status. It must be connected directly to the Vcore supply.
This pin provides the feedback for the AGP linear regulator. The Select pin when connected to the "Type Detect" pin of the AGP slot automatically selects the right voltage for
the AGP Vddq.
This pin controls the gate of an external MOSFET for the 1.8V chip set linear regulator.
This pin is connected to the Drain of the power MOSFET of the Core supply and it
provides the positive sensing for the internal current sensing circuitry. An external resistor programs the C.S threshold depending on the Rds of the power MOSFET. An external
capacitor is placed in parallel with the programming resistor to provide high frequency
noise filtering.
This pin is connected to the Source of the power MOSFET for the Core supply and it
provides the negative sensing for the internal current sensing circuitry.
This pin provides the soft start for all the regulators. An internal current source charges
an external capacitor that is connected from this pin to GND which ramps up the outputs
of the regulators, preventing the outputs from overshooting as well as limiting the input
current. The second function of the Soft Start cap is to provide long off time (HICCUP) for
the synchronous MOSFET during current limiting.
This pin has dual function. It acts as an output of the OVP circuitry or it can be used to
program the frequency using an external resistor . When used as a fault detector, if any
of the switcher outputs exceed the OVP trip point, the FAULT pin switches to 12V and
the soft start cap is discharged. If the FAULT pin is to be connected to any external
circuitry, it needs to be buffered.
This pin controls the gate of an external transistor for the 1.5V GTL+ linear regulator.
This pin provides the feedback for the linear regulator that its output drive is Drive3.
This pin is not connected internally.
14Vsen4
17GND
24PGND
25LGATE
27UGATE
28V12
20V5
11Select
2
This pin provides the feedback for the linear regulator that its output drive is Drive4.
This pin serves as the ground pin and must be connected directly to the ground plane.
This pin serves as the Power ground pin and must be connected directly to the GND
plane close to the source of the synchronous MOSFET. A high frequency capacitor
(typically 1 uF) must be connected from V12 pin to this pin for noise free operation.
Output driver for the synchronous power MOSFET for the Core supply.
Output driver for the high side power MOSFET for the Core supply.
This pin is connected to the 12 V supply and serves as the power Vcc pin for the output
drivers. A high frequency capacitor (typically 1 uF) must be placed close to this pin and
PGND pin and be connected directly from this pin to the GND plane for the noise free
operation.
5V supply voltage. A high frequency capacitor (0.1 to 1 uF) must be placed close to this
pin and connected from this pin to the GND plane for noise free operation.
This pin provides automatic voltage selection for the AGP switching regulator. When it is
pulled LO, the voltage is 1.5V and when left open or pulled to HI, the voltage is 3.3V.
Leaving this pin open provides fixed output voltages of the 1.5V and 1.8V for the #3 and #4
linear regulators. When this pin is grounded the reference to the linear regulators are set
to 1.26V and therefore the output of the regulators can be programmed to any voltages
above the 1.26V using; Vout=1.26*(1+Rtop/Rbot)
Where:
Rtop=Top resistor connected from the output to the Vsense pin
Rbot=Bottom resistor connected from the Vsense pin to ground.
Rev. 1.3
12/8/00
4-5
Page 6
US3021M
BLOCK DIAGRAMBLOCK DIAGRAM
V12
V5
SD
Vsen1
PGood
Vsen3
Vsen4
Fix
Drive4
Drive3
Select
Drive2
Vsen2
UVLO
1.26V
Enable
Fb
1.17Vset
Over
Voltage
Vset
Enable
V12
UGate
PWM
1.1Vset
+
Slope
Comp
Osc
Control
V12
LGate
Phase
Soft
0.9Vset
Enable
Start &
Fault
Logic
R
3R
Over
Current
200uA
Vset
OCSet
PGnd
Gnd
Fault / Rt
SS
VID0
1.5V
R
3R
3.3V
5Bit
DAC
3021Mblk1-1.0
VID1
VID2
VID3
VID4
4-6
Figure 1 - Simplified block diagram of the US3021M.
Rev. 1.3
12/8/00
Page 7
TYPICAL APPLICATIONTYPICAL APPLICATION
(Dual Layout with HIP6021)
US3021M
12V
Type Detect
3.3Vin
Vout2
1.5V / 3.3V
Vout3
1.5V
Vout4
1.8V
R1
L1
5V
C1
C6
C2
R3
R5
Q2
C13
Q4
C18
Q5
3021Mapp2-1.2
C19
28
V12
SD
9
FIX2
SELECT
11
NC
16
(Vaux)
DRIVE2
1
VSEN210
DRIVE3
18
VSEN3
19
DRIVE4
15
VSEN4 GND
U1
1714
23
OCSET
UGATE 27
PHASE
LGATE
PGND
VSEN1
(COMP)
VID0
VID1
VID2
VID3
VID4 3
PGOOD 8
FAULT/RT
SS
12
R4
26
R7
25
24
22
21
FB
R9
V5
20
C15
7
6
5
4
13
C20
C17
Q1
Q3C22
C16
R12
Vcc3
R14
R8
C3C4R2C5
L2
Vcore
C7
R6
R10
C14
R11
R13
PGood
C21
Figure 2 - Typical application of US3021M in a dual layout with HIP6021 for an on board DC-DC converter
providing power for the Vcore , GTL+, 1.8V chip set supply as well as auto select AGP supply for the next