ADP1074

Data Sheet

Rev. D | Page 12 of 32

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

SR1

24

SR2

23

PGND2

22

AGND2

21

VREG2

20

VDD2

19

OVP

18

FB

17

COMP

16

SS2

15

PGOOD

14

MODE

13

ADP1074

(Not to Scale)

TOP VIEW

Figure 4. 24-Lead SOIC_W Pin Configuration

AGND1

COMP

4

VREG1

5

VIN

6

EN

7

CS

8

RT

9

13

14

15

16

FB

17

OVP

18

VDD2

19

VREG2

20

AGND2

21

22

23

24

1

2

3

TOP VIEW

(TERMINAL SIDE DOWN)

Not to Scale

ADP1074

10

11

12

AGND1

AGND2

Figure 5. 24-Terminal LGA Pin Configuration

Table 12. Pin Function Descriptions

Pin No.

Mnemonic

Description

1

NGATE

Driver Output for the Main Power MOSFET on the Primary Side. Multiple function pin. Connect a resistor from

NGATE to PGND1 to set up the predetermined dead time between PGATE and SR2.

2

PGATE

Driver for the Active Clamp MOSFET of the Forward Topology. This pin is referenced to PGND1.

3

PGND1

Power Ground on the Primary Side. Star connect this pin to AGND1.

4

AGND1

Analog Ground on the Primary Side. Star connect this pin to PGND1. Use this pin to differentially sense the

primary current sensed with the sense resistor between the CS and AGND1 pins.

5

VREG1

8 V Output for the MOSFET Drivers. Connect 1 μF or greater at this pin. Do not put an external load on this pin.

Reference this pin to PGND1.

6

VIN

Input Voltage. Connect a 4.7 μF capacitor to this pin. The size of this capacitor can be reduced if the input

voltage to this pin is guaranteed stable. Reference this pin to PGND1.

7

EN

Precision Enable Input. The controller is enabled when the voltage at the EN pin is above the EN threshold

voltage. Soft stop is enabled when EN drops below the EN threshold voltage. This pin also has a programmable

EN hysteresis. Reference this pin to AGND1.

8

CS

Input Current Sensing. This pin senses the input pulse width modulated current. Place a current sense resistor

between the source terminal of the power MOSFET and PGND1. This current sense resistor sets up the input

current limit. This pin is also used for an external slope compensator. Connect a resistor from CS to the current

sense resistor to generate a voltage ramp for the slope compensation. Reference this pin to AGND1. Connect a

33 pF to 100 pF capacitor to this pin to act as a resistor capacitor (RC) filter along with the slope compensation

resistor in noisy environments.

9

RT

Switching Period Resistor. Connect two resistors in series that sum up to the appropriate resistor from RT to

AGND1 to set the switching frequency. See the DMAX pin for more information. Also see the Frequency Setting

(RT Pin) section and the Maximum Duty Cycle section for the relevant equations.

10

SYNC

Frequency Synchronization. Connect an external clock to the SYNC pin to synchronize the internal oscillator to

this external clock frequency. Connect SYNC to AGND1 if this feature is not used. It is recommended that the

SYNC frequency be within 10% of the frequency set by the RT pin.

11

SS1

Soft Start 1. Connect a capacitor at this pin to set up the open-loop soft start time. Reference this pin to AGND1.

12

DMAX

Maximum Duty Cycle Control. Connect DMAX to the center tap of the resistive divider at the RT pin to set up the

maximum duty cycle. See the Frequency Setting (RT Pin) section and the Maximum Duty Cycle section for the

relevant equations.

13

MODE

Light Load Mode Setting. Connect MODE to AGND2 to disable discontinuous conduction mode (DCM)

operation, or to a high logic (2.5 V or higher, such as the VREG2 pin) to force LLM operation, or to a resistor to set

up a fixed LLM threshold voltage.

14

PGOOD

Power Good Pin. Open-drain output. Connect a pull-up resistor from PGOOD to VREG2.

15

SS2

Soft Start on the Secondary Side. Connect a capacitor from SS2 to AGND2 to set up the soft start time on the

secondary side.