STLC3085

Functional description

19/28

T1

DC/DC Converter transformer

Fly-Back transformer 4W, Turns

Ratio 1:8 fro VPOS range from

8.5V to 12V

Tyco COEV MAGNETICS

MGPWG-00008

RF1

Negative battery programming

level

250K

Ω<RF1<270KΩ

270k

Ω 1% @ V

RF2

Negative battery programming

level

9.1k

Ω 1%

@Gain Set = 0

RS

Protection resistance image

RS = 50

⋅ (2Rp)

5k

Ω @ Rp = 50Ω

ZAC

Two wire AC impedance

ZAC = 50

⋅ (Zs - 2Rp)

25k

Ω 1% @ Zs = 600Ω

SLIC impedance balancing

network

ZA = 50

⋅ Zs

30k

Ω 1% @ Zs = 600Ω

Line impedance balancing

network

ZB = 50

⋅ Zl

30k

Ω 1% @ Zl = 600Ω

CCOMP

AC feedback loop compensation

fo = 250kHz

CCOMP = 1/(2

π⋅fo⋅100⋅(RP))

120pF 10% 10V @ Rp = 50

Ω

CH

Trans-Hybrid Loss frequency

compensation

CH = CCOMP

120pF 10% 10V

@Gain Set = 1

RS

Protection resistance image

RS = 25

⋅ (2Rp)

2.55k

Ω @ Rp = 50Ω

ZAC

Two wire AC impedance

ZAC = 25

⋅ (Zs - 2Rp)

12.5k

Ω 1% @ Zs = 600Ω

SLIC impedance balancing

network

ZA = 25

⋅ Zs

15k

Ω 1% @ Zs = 600Ω

Line impedance balancing

network

ZB = 25

⋅ Zl

15k

Ω 1% @ ZI = 600Ω

CCOMP

AC feedback loop compensation

fo = 250kHz

CCOMP = 2/(2

π⋅fo⋅100⋅(RP))

220pF 10% 10VL @ Rp = 50

Ω

CH

Trans-Hybrid Loss frequency

compensation

CH = CCOMP

220pF 10% 10V

(1) CVpos should be defined depending on the power supply current capability and maximum allowable ripple.

(2) For low ripple application use 2x47 µF in parallel.

(3) Can be saved if proper PCB layout avoid noise coupling on RD pin (high impedance input).

(4) For high efficiency in HI-Z mode coil resistance @125kHz must be < 3

Ω.

(5) In case Zs=Zl, ZA and ZB can be replaced by two resistors of same value: RA=RB=|Zs|.

Table 10.

External Components (continued)