ADP1050ACPZ-R7 datasheet(29/93 Pages) AD

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ADP1050

Data Sheet

VOLTAGE READINGS

Input Voltage Reading

The input voltage, which is reported in the READ_VIN command

(Register 0x88), is updated every 10 ms. The VIN_SCALE_

MONITOR command (Register 0xD8) is set for correct input

voltage reading.

The input voltage is sensed through the VF pin (Pin 4). The

VF ADC has an input range of 1.6 V. The raw data is stored in

is 1.6 V/2048 = 781.25 μV.

Because the input voltage signal can be sensed through the

switching node of the secondary windings, the voltage drop

caused by the conduction current in the primary switches,

transformer windings, and copper trace adds to the error to

the input voltage sense. The following equation is used to

compensate for the error:

YCOMP = YUNCOMP ± (N × X ÷ 211)

where:

YCOMP is the compensated VF value in Register 0xFEAC[15:5].

YUNCOMP is the uncompensated VF value in Register 0xFEAC[15:5].

N is the compensation coefficient set in Register 0xFE59[7:0],

and the polarity is set in Register 0xFE58[0].

X is the CS1 current value in Register 0xFEA7[15:4].

The compensated VF value is used for conversion of the

READ_VIN value.

Output Voltage Reading

The output voltage is reported in the READ_VOUT command

(Register 0x8B) and updated every 10 ms. The VOUT_SCALE_

MONITOR command (Register 0x2A) is programmed for correct

output voltage reading.

The VS voltage value register (Register 0xFEAA) is updated

every 10 ms via the VS low frequency ADC.

The VS low frequency ADC has an input range of 1.6 V. The raw

data is stored in Register 0xFEAA. The reading is 12 bits, which

means that the LSB size is 1.6 V/4096 = 390.625 μV.

CURRENT READINGS

By default, the current readings are updated every 10 ms; however,

52 ms, 105 ms, or 210 ms.

Input Current Reading

The input current is reported in the READ_IIN command

(Register 0x89). The IIN_SCALE_MONITOR command

(Register 0xD9) is set for correct input current reading.

The input current reading is derived from the CS1 ADC, which has

an input range of 1.6 V. The raw data is stored in Register 0xFEA7.

The reading is 12 bits, which means that the LSB size is 1.6 V/

4096 = 390.625 μV.

CS3 Current Reading

The CS3 reading is an alternative output current reading that is

calculated using the CS1 reading and the duty cycle values. The

CS3 reading can be used as an alternate output current reading

and protection when the current sense resistor is not used. The

output current reading is derived from the following equation:

IOUT = ICS3 × n

where ICS3 is read from Register 0xFEA9[15:4], and n is the turns

ratio of the main transformer (n = NPRI/NSEC).

Each LSB size in Register 0xFEA9[15:4] is 4× the LSB size of the

CS1 reading in Register 0xFEA7. For example, if 1 LSB = 0.1 A

in Register 0xFEA7[15:4], 1 LSB in Register 0xFEA9[15:4] = 0.4 A.

POWER READINGS

Input Power Reading

The input power value (Register 0xFEAE) is the product of the

VF voltage value in Register 0xFEAC[15:5] and the CS1 current

value in Register 0xFEA7[15:4]. Therefore, a combination of both

voltage and current formulas is used to calculate the power reading

in watts (W). Register 0xFEAE is a 16-bit word. It multiplies two

12-bit numbers and then discards the eight LSBs.

For example, if 1 LSB in Register 0xFEAC[15:5] is 0.01 V and 1

LSB in Register 0xFEA7[15:4] is 0.01 A, 1 LSB in Register

0xFEAE[15:0] is 0.01 V × 0.01 A × 28 = 0.0256 W.

DUTY CYCLE READING

The READ_DUTY_CYCLE command (Register 0x94, which gives

the duty cycle of the PWM output value) is updated every 10 ms.

type topologies; these bits select the PWM channel (OUTA or

OUTB) for which the duty cycle value is reported.

SWITCHING FREQUENCY READING

The READ_FREQUENCY command (Register 0x95) is used to

report the switching frequency information in kHz.

Rev. A | Page 28 of 92

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