R + R

D

S

S

D1

G1

S1

V

0.6V

REF

VREG5

Channel1

V + V

D

S

S

I

=

LED

V + V

D

S

S

R + R

S

S

D

V

S

R

S

»

1+

DVS

V

S

-

DRS

R

S

DI

=

LED

V

S

R

S

DVS

V

S

-

DRS

R

S

TLC5960

SBVS147 – SEPTEMBER 2010

www.ti.com

CHANNEL-TO-CHANNEL CONSTANT CURRENT MISMATCH RATING

The current mismatch rate between channels is primarily induced by the external sense resistor mismatch rating.

Additionally, the TLC5960 driver input offset contributes to the current mismatch rating between the channels.

The gate drive amplifier offset (VOFFSET) is specified in the Electrical Characteristics.

Figure 17. Channel-to-Channel Mismatch Factors

Figure 17 shows the mismatch contributing factors on this system.

ΔRS represents the resistor mismatch. ΔVS

denotes the contribution of the gate amplifier input equivalent offset, VOFFSET. Using these two external and

internal error factors, the total mismatch rate is estimated in Equation 3. In this case, with a 1% accurate RS

used, the total current mismatch value is estimated within 1.9%.

(3)

14

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