ADP1048WARQZ-R7 datasheet(31/82 Pages) AD

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Data Sheet

ADP1048W

Three load lines address super high line, high line, and low line

input voltage conditions.

When the rms value of the input voltage is higher than the super

high line input (for example, 250 V), the load line is flat, that is,

the output voltage remains at VOH, which is independent of the

power. To avoid output voltage oscillation when the input voltage

is around the super high line level, voltage hysteresis can be

programmed using Register 0xFE4D. It is recommended that

at least 16 V of hysteresis be programmed.

When the rms value of the input voltage is lower than the super

high line input but higher than the high line threshold, there is

a load line between P1 and P2 in terms of power. The output

voltage varies between VOH1 and VOH2 as a linear function

of the output power when the output power falls within the

range between P1 and P2. The power levels of P1 and P2 are

programmable using Register 0xFE44 and Register 0xFE45,

respectively. When the power is below P1, the output voltage

remains unchanged at VOH1. When the power is higher than

P2, the output voltage remains unchanged at VOH2.

The bottom load line in Figure 26 applies when the rms value of

the input voltage is lower than the low line threshold. The output

voltage varies between VOL1 and VOL2 as a linear function of

the output power when the output power falls within the range

between P1 and P2. When the power is below P1, the output

voltage remains unchanged at VOL1. When the power is higher

than P2, the output voltage remains unchanged at VOL2.

The user can program values for VOH, VOH2, VOH1, VOL2, and

VOL1 using Register 0xFE4A, Register 0xFE49, Register 0xFE48,

SMART SWITCHING FREQUENCY

For higher efficiency, the switching frequency of the

ADP1048W can be programmed according to the load power

condition (see Figure 27). To enable the smart switching

frequency feature, set Register 0xFE4F, Bit 3, to 1.

Figure 27. Smart Switching Frequency Control

The smart switching frequency feature uses two different

switching frequencies for heavy load and light load conditions.

When the output power is lower than the low power threshold,

PTH, the PFC circuit switches at the fSL frequency. When the out-

put power is higher than PTH plus power hysteresis, the circuit

switches at the normal set frequency, fS.

Hysteresis can be programmed in Register 0xFE4E. The user

can program the values for fSL and PTH in Register 0xFE1C and

CURRENT LOOP FILTER FOR LIGHT LOAD

To achieve low THD under light load conditions, the ADP1048W

offers current loop filter presets for light load operation under

both high line input and low line input (see Figure 28). To enable

the current loop filter for light load feature, set Register 0xFE4F,

Bit 5, to 1.

Figure 28. Current Loop Filter at Light Load Condition

When the input power drops below the low power threshold, PTH

(set in Register 0xFE32), the current loop filter switches to the

light load filter after four full line cycles. When the input power

goes above PTH plus the programmed hysteresis, the current loop

filter switches back to the normal mode filter immediately. This

applies to both high line and low line input.

PHASE SHEDDING

To achieve high efficiency at light load, the ADP1048W can

shut down one PWM output under light load conditions. When

the input power drops below the low power threshold, PTH (set

in Register 0xFE32), one PWM output is disabled. When the

input power goes above the low power threshold plus power

hysteresis (set in Register 0xFE4E), the PWM resumes operation.

To enable phase shedding for the ADP1048W, set Register

0xFE4F, Bit 4, to 1.

CURRENT LOOP FEEDFORWARD

Current loop feedforward is implemented in the ADP1048W to

improve the power factor and reduce THD under light load

conditions (see Figure 29). To enable current loop feedforward,

set Register 0xFE4F, Bit 6, to 1.

Figure 29. Current Loop Feedforward

POWER

fSL

FULL POWER

PTH

SWITCHING

FREQUENCY

HIGH LINE

LIGHT LOAD

HIGH LINE

LOW LINE

LIGHT LOAD

INPUT POWER

POWER

THRESHOLD

LOW LINE

HIGH/LOW LINE

THRESHOLD

AC LINE

VAC

–VREF

–

IREF

HI (z)

DUTY CYCLE

Rev. 0 | Page 31 of 82

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