UCD3028RMHT datasheet(29/81 Pages) TI1

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EAPx

EANx

DACVAL

Result

800mV

Vrefp

Vrefm

Veadp

Veadm

EAPx

EANx

EADC DAC

10-Bit

EADC

6-Bit

–

Thermo

-to-

2'sComp

UCD3040

UCD3028

UCD3020

www.ti.com

SLUS868H – DECEMBER 2009 – REVISED OCTOBER 2013

PERIPHERALS

Fusion Digital Power Peripherals

At the core of the UCD30xx controller are its four Fusion Digital Power peripherals (FDPP). Each FDPP can be

configured to drive from one to eight DPWM outputs. Each FDPP consists of a differential input error ADC

(EADC), a hardware-accelerated digital three-pole/three-zero (3p/3z) compensator, and a digital PWM module.

Error ADC (EADC) Module

Programmer's Reference Manual: UCD30xx Fusion Digital Power Peripherals Programmer’s Manual

For initialization of the EADC module, see the UCD30xx Fusion Digital Power Peripherals Programmer’s

Manual.

The EADC module within the UCD30xx is shown in Figure 4. It contains a differential input, switch-capacitor filter

circuit for receiving the differential voltage signal (signal being sensed) from external pins EAPx and EANx. It is

compared with an internal 10-bit DAC output in order to measure the error voltage signal. Gain control (G) is

provided in the amplifier for 1-, 2-, 4-, or 8-times amplification of the differential error signal. This error signal is

then summed with an internal reference voltage (800 mV) and compared against this same reference voltage as

input to the EADC module. Thus the error signal input to EADC is:

Error = G × [(Vrefp – Vrefm) – (EAPx – EANx)]

The full-scale of the EADC range is effectively 512 mV (8 mV times 64). Finally, the EADC value is converted

from thermometer code to a 2s-complement value for digital processing.

Figure 4. Error ADC Module

The EADC control logic receives the sample request from the DPWM module for initiating an EADC conversion.

EADC control circuitry captures the EADC 6-bit code and strobes the 3p/3z digital compensator for processing of

the representative error.

Table 3. EADC and DAC Parameters

EADC

Input differential range (EAPx – EANx)

0 V–1.6 V

Common-mode range (EAPx, EANx)

0 V–1.6 V

Input impedance

1.5 M

Ω (typical)

Sampling rate

> 10 Msps

Conversion time

< 100 nS

INL

±2 LSB (max)

DNL

±1 LSB (max)

Gain error

±1 LSB (~1.5% max)

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