Document
US3027
5 BIT PROGRAMMABLE SYNCHRONOUS BUCK PLUS TRIPPLE LDO CONTROLLER
PRELIMINARY DATASHEET
FEATURES
Designed to meet VRM 9.0 specification for next generation micrprocessors On board 5 bit DAC programs the output voltage from 1.075V to 1.850V in 25mV steps Linear regulator controller on board for 1.8V 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 1.5V 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
DESCRIPTION
The US3027 controller IC is specifically designed to meet VRM 9.0 specification for next generation microprocessor applications requiring multiple on board regulators . The US3027 provides a single chip controller 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 US3027 is designed to use either Bipolar transistors for Vout3(1.5V) and Vout4(1.8V) or if Vaux pin is connected to 12V, then MOSFETs can also be used as external pass elements. 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 US3027 also features, loss less current 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 window comparator that switches its open collector output low when any one of the outputs is outside of a pre programmed window.
APPLICATIONS
Total Power Soloution for Next Generation Intel Processor application AMD K7 Low Cost Solution
TYPICAL APPLICATION
5V 3.3V LINEAR CONTROL SWITCHER CONTROL Vout1
Vout2
US3027
LINEAR CONTROL Vout3
LINEAR CONTROL Vout4
3027app3-1.0
PACKAGE ORDER INFORMATION
Ta (°C) 0 TO 70
Rev. 1.3 12/8/00
Device US3027CW
Package 28 pin Plastic SOIC WB
4-1
US3027
ABSOLUTE 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
PACKAGE INFORMATION
28 PIN WIDE BODY PLASTIC SOIC (W)
TOP VIEW
Drive2 1 Fix 2 VID4 3 VID3 4 VID2 5 VID1 6 VID0 7 PGood 8 SD 9 Vsen2 10 Select 11 SS 12 Fault / Rt 13 Vsen4 14
28 V12 27 UGate 26 Phase 25 LGate 24 PGnd 23 OCSet 22 Vsen1 21 Fb 20 V5 19 Vsen3 18 Drive3 17 Gnd 16 NC 15 Drive4
θJA =80°C/W
ELECTRICAL SPECIFICATIONS
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. PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS Supply UVLO Section UVLO Threshold-12V Supply ramping up 10 V UVLO Hysterises-12V 0.6 V UVLO Threshold-5V Supply ramping up 4.4 V UVLO Hysterises-5V 0.3 V Supply Current Operating Supply Current V12 6 mA V5 30 Switching Controllers; Vcore (Vsen 1) and AGP (Vsen 2) VID Section (Vcore only) DAC output voltage (note 1) 0.99Vs Vs 1.01Vs V DAC Output Line Regulation 0.1 % DAC Output Temp Variation 0.5 % VID Input LO 0.8 V VID Input HI 2 V VID input internal pull-up resistor to V5 27 kΩ Vsen2 Voltage Select<0.8V 1.5 V Select>2V 3.3 V
4-2
Rev. 1.3 12/8/00
US3027
Error Comparator Section Input bias current Input Offset Voltage Delay to Output Current Limit Section C.S Threshold Set Current C.S Comp Offset Voltage Hiccup Duty Cycle Output Drivers Section Rise Time Fall Time Dead band Time Between High side and Synch Drive (Vcore Switcher Only) Oscillator Section (internal) Osc Frequency 1.8V Regulator (Vsen 4) Vsense Voltage Vo4 Vsense Voltage Input bias current Output Drive Current 1.5V Regulator (Vsen 3) Vsense Voltage Vsense Voltage Input bias current Output Drive Current Power Good Section Vsen1 UV lower trip point Vsen1 UV upper trip point Vsen1 UV Hysterises Vsen1 HV upper trip point Vsen1 HV lower trip point Vsen1 HV Hysterises Vsen2 trip point Vsen4 trip point Vsen3 trip point Power Good Output LO Power Good Output HI .