HT2801S

5/6

High Accuracy CV/ CC Primary Sensing Regulation Controller IC

www.hotchip.com.cn

Ver1.0

inductance which also

affects the output current. The corresponding relation between the

primary peak current and the

secondary peak current is as follows--

primary winding turns;

NS: secondary

winding turns;

And primary inductance peak current is determined by Pin 4 to RCS resistance, the primary

inductance peak current and RCS resistance are in inverse proportion, so only need to adjust CS

resistance to achieve different output currents. Output current Iout and

Primary Current is given by the following equation--

(Where Iout: Output current; Tons: secondary rectifier diode on-time; Toffs: secondary rectifier diode off-time)

Cable Drop- out Compensation

HT2801S is featured with output cable drop- out compensation circuit. When it outputs with

different loads, this certain circuitry compensates cable voltage which is in fixed proportion with

output voltage. The internal circuit will generate one cable drop compensation signal once a

capacitor of 100nF is connected with CPC Pin

Protection Function

To assure a safe and reliable circuit in all application, HT2801S features multiple protection

circuits covering OCP, OVP, FB open-loop protection etc. as integration. Once abnormality is

been defected, Protection mode of all kinds is therefore triggered

.

Note: Referential Replacement Circuitry of typical RCC Circuit

C1

D1-D4

R2

R3

C3

D5

C2

D6

C4

VCC

CPC

GND

CS

FB

HV

R4

U1

HT2801

R5

R6

C5

D7

R7

VO-

VO+

+

-

T1

100-

240Vac

R1