Texas Instruments Incorporated
`
`Power Management
`
`Extended output voltage adjustment
`(0 V to 3.5 V) using the TI TPS5210
`
`By Bang Sup Lee
`Application Specialist, Power Management
`This application note describes the design of a 12-V
`input/0-V to 1.3-V output synchronous buck regulator
`using the TI TPS5210 programmable controller. Although
`the output voltage can be extended down to 0 V to 1.3 V
`using the auxiliary circuitry described in this note, the
`supply will still be capable of providing an output voltage
`range from 1.3 V to 3.5 V, determined by the voltage iden-
`tification code (VID).
`The TPS5210, a synchronous buck regulator controller,
`provides an accurate, programmable supply voltage suit-
`able for microprocessor power applications that require
`fast response to rapidly changing loads and precise voltage
`regulation.
`A simplified diagram of the regulator circuit is shown in
`Figure 1. The diagram shows the 1% voltage reference,
`hysteresis control and gate drivers with adaptive dead-
`time control. The reference voltage ranging from 1.3 V to
`3.5 V is determined by the VID. The hysteresis controller
`senses the output voltage through the feedback loop
`(VSENSE pin) and the supply regulates the DC voltage level
`to the reference value (VREF) set using the data on the
`VID pins. When the feedback voltage VSENSE is rescaled to
`a specific value, the regulator output voltage can be
`extended to 0 V to 1.3 V.
`Figure 2 shows the application circuit of the extended
`1-V output, which is identical to the application shown in
`
`Figure 1. Synchronous buck regulator using
`the TPS5210
`
`Input
`12 V
`
`L1
`
`C1
`
`TPS5210
`
`HIGHDR
`
`Adaptive
`Deadtime
`Control
`
`LOWDR
`
`VSENSE
`R2
`10kW
`
`L2
`
`Output
`
`C2
`
`R1
`150W
`
`C3
`1000 pF
`
`VREF
`
`Selection
`of VREF
`by VID
`
`VID0
`VID1
`VID2
`VID3
`VID4
`
`Figure 2. 1-V regulator using the TPS5210
`
`12 V
`
`VCC
`
`5 V
`
`VID0
`VID1
`VID2
`VID3
`VID4
`
`L1
`
`Input
`12 V
`
`TPS5210
`
`C1
`
`HIGHDR
`
`LOWDR
`
`DRVGND
`
`VSENSE
`
`L2
`
`C2
`
`1-V
`Output
`
`R1
`150W
`
`R3
`2.3kW
`
`R4
`1.3kW
`
`R5
`47W
`
`12 V
`
`Auxiliary Circuit
`
`R2
`10kW
`
`C3
`1000 pF
`
`Dz
`6.2 V
`
`Adding a few inexpensive components in the feedback path of
`TPS5210 enables the generation of 0-V to 1.3-V regulated.
`
`Figure 1 (TPS5210 data sheet, literature number
`SLVS171A, Figure 18), except for the auxiliary circuit.
`To operate the circuit for a 1-V output, the voltage ref-
`erence (VREF) should be set to 1.3 V using the VID code.
`The internal hysteresis comparator in the TPS5210 regu-
`lates the output voltage to 1.3 V, comparing VREF (1.3 V)
`with the output feedback voltage, VSENSE. Since the output
`voltage feedback signal (VSENSE) is scaled to 1.3/1.0 V
`(VSENSE/VOUT) by using a resistive voltage divider (R1-R3)
`as shown in Figure 2, the output voltage is regulated at
`1 V. The demand resistor (R3) value required for a 1-V
`output is calculated using Equation 1.
`
`=
`3R
`
`DZ VV
`SENSE
`VVV
`+
`SENSEOUTSENSE
`150
`2R1R
`
`=
`
`3.12.6
`+
`0.13.1
`3.1
`k10
`
`W=
`(1)
`k3.2
`This method can also be applied to any output voltage
`ranging between 0 V to 1.3 V by using the above equation.
`
`Analog Applications
`
`August 1999
`
`Analog and Mixed-Signal Products
`
`www.ti.com/sc/docs/products/analog/tps5210.html
`
`13
`
`MICROCHIP TECHNOLOGY INC. EXHIBIT 1040
`Page 1 of 2
`
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`SLYT195
`
`MICROCHIP TECHNOLOGY INC. EXHIBIT 1040
`Page 2 of 2
`
`