Texas Instruments UCC391PW, UCC391P Datasheet

UCC391

ADVANCE INFORMATION

DESCRIPTION

The UCC391 provides an accurate reference, programmable by a 5-bit DAC, in a tiny 8 pin package. Using few external components, the UCC391 converts 5V to an adjustable output ranging from 3.5VDC to 2.1VDC in 100mV steps and 2.05VDC to 1.3VDC in 50mV steps with 1% DC system accuracy.

This device is available in and 8 pin surface mount (150mm SOIC) and TSSOP packages and is specified for operation from 0°C to 70°C.

5-Bit Programmable Output BiCMOS Precision Voltage Reference

FEATURES

•

5 - Bit Digital-to-Analog Converter (DAC) supports Intel Pentium II Microprocessor VID Codes

•

Compatible with 5V Systems

•

1% Output Voltage Accuracy Guaranteed

SLUS437 - NOVEMBER 1998

VCC

COMMAND

GND

DAC

VREF

BLOCK DIAGRAM

UDG-98200

UCC391

MSOP-8, TSSOP-8 (TOP VIEW) P, PW Packages

ABSOLUTE MAXIMUM RATINGS

Supply Voltage VCC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8V

Input Voltage, D0, D1, D2, D3, D4 . . . . . . . . . . . . . . . . . . . . 8V

Currents are positive into, negative out of the specified termi

nal. Consult Packaging Section of Databook for thermal limita

tions and considerations of packages. All voltages are referenced to GND.

GND

COMMAND

VCC

CONNECTION DIAGRAMS

ELECTRICAL CHARACTERISTICS:

Unless otherwise specified these specifications hold for TA= 0°C to 70°C for the

UCC391, T

A=TJ.VCC

= 5V.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Supply Current Section

Supply Current, On V

= 5V 1.8 mA

DAC Reference Section

COMMAND Voltage Accuracy 4.5V < V

< 5.5V, measured on COMMAND, 0°C

< T

< 70°C (Note 1)

–1.00 1.00 %

D0 – D4 Voltage High 4.5 5 5.5 V

D0 – D4 Voltage Threshold 2.5 V

D0 – D4 Input Bias Current V(D4, D3, D2, D1, D0) < 0.5V –90 –20

µA

Output Current (Maximum Load) I

OUT(VCOMMAND

) 0 150 µA

Note 1: Reference and output amplifier offsets are trimmed out before packaging.

GND: (Ground) All voltages measured with respect to

ground. VCC should be bypassed directly to GND with a

0.1µF or larger ceramic capacitor.

VCC: (Positive supply voltage) This pin is normally con

nected to a 5V ± 10% system voltage. Bypass VCC di

rectly to GND with a 0.1µF (minimum) ceramic capacitor.

COMMAND: This pin is the output of the IC. It is con

trolled by the 5-bit input word (D0:D4). This output will have a ±1% system accuracy over temperature, process, and input voltage.

D0, D1, D2, D3, D4: These are the digital input control codes for the DAC. The DAC is comprised of two ranges set by D4, with D0 representing the least significant bit (LSB) and D3, the most significant bit (MSB). A bit is set low by being connected to GND; a bit is set high by float

ing the pin. Each control pin is pulled up to approximately 5V by an internal pull-up. If all ones are commanded on the DAC inputs (no CPU command), the output will be disabled.

PIN DESCRIPTIONS

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