Lattice Semiconductor

ispPAC-POWR6AT6 Data Sheet

13

Figure 8 shows the resistor network between the TrimCell #N in the ispPAC-POWR6AT6 and the DC-DC converter.

The values of these resistors depend on the type of DC-DC converter used and its operating voltage range. The

method to calculate the values of the resistors R1, R2, and R3 are described in a separate application note.

Voltage Profile Control

The Margin / Trim Block of ispPAC-POWR6AT6 consists of six TrimCells. Because all six TrimCells in the Margin /

Trim Block are controlled by a common voltage profile control signals, they all operate at the same voltage profile.

The voltage profile control input comes from a pair of device pins: VPS0, VPS1.

TrimCell Architecture

The TrimCell block diagram is shown in Figure 9. The 8-bit DAC at the output provides the trimming voltage

required to set the output voltage of a programmable supply. Each TrimCell can be operated in any one of the four

voltage profiles. In each voltage profile the output trimming voltage can be set to a preset value. There are six 8-bit

registers in each TrimCell that, depending on the operational mode, set the DAC value. Of these, four DAC values

(DAC Register 0 to DAC Register 3) are stored in the E

stored in volatile registers. Two multiplexers (Mode Mux and Profile Mux) control the routing of the code to the DAC.

The Profile Mux can be controlled by common TrimCell voltage profile control signals.

Figure 9. ispPAC-POWR6AT6 Output TrimCell

Figure 7 shows four power supply voltages next to each DC-DC converter. When the Profile MUX is set to Voltage

Profile 3, the DC supply controlled by Trim 1 will be at 0.95V, the DC supply controlled by Trim 2 will be at 1.14V,

1.42V for Trim 3 and 3.13V for Trim 8. When Voltage Profile 0 is selected, Trim 1 will set the supply to 1V, Trim 2 and

Trim 3 will be set by the values that have been loaded using I

The following table summarizes the voltage profile selection and the corresponding DAC output trimming voltage.

The voltage profile selection is common to all six TrimCells.

DAC REGISTER 0

CLOSED LOOP

TRIM REGISTER

DAC REGISTER 3

VOLTAGE PROFILE 0

MODE SELECT

(E2CMOS)

DAC

00

01

10

11

TRIMx

2

8

8

8

8

8

8

8

DAC REGISTER

(I

8

VOLTAGE

PROFILE 3

VOLTAGE

PROFILE 2

VOLTAGE

PROFILE 1

VOLTAGE

PROFILE 0

DAC REGISTER 2

DAC REGISTER 1

FROM CLOSED LOOP

TRIM CIRCUIT

TRIMCELL ARCHITECTURE

COMMON TrimCell

VOLTAGE PROFILE

CONTROL