ONET1101L Datasheet, PDF (11/26 Pages) Texas Instruments – 11.3 Gbps Laser Diode Driver

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ONET1101L
SLLS883 – MARCH 2008
SYMBOL REGISTER BIT
ENA
Enable bit 7
PDRNG1 Photodiode current range bit 6
PDRNG0 Photodiode current range bit 5
OLENA Open loop enable bit 4
FLTEN
Fault detection enable bit 3
POL
Output polarity switch bit 2
EQENA Equalizer enable bit 1
PDPOL Photodiode polarity bit 0
OCDIS
Offset cancellation disable bit 3
BIASPOL Bias current polarity bit 2
CPRNG1 Cross point range bit 1
CPRNG0 Cross point range bit 0
MODC9
MODC8
MODC7
MODC6
MODC5
MODC4
MODC3
MODC2
MODC1
MODC0
BIASC9
BIASC8
BIASC7
BIASC6
BIASC5
BIASC4
BIASC3
BIASC2
BIASC1
BIASC0
Modulation current bit 9 (MSB)
Modulation current bit 8
Modulation current bit 7
Modulation current bit 6
Modulation current bit 5
Modulation current bit 4
Modulation current bit 3
Modulation current bit 2
Modulation current bit 1
Modulation current bit 0 (LSB)
Bias current bit 9 (MSB)
Bias current bit 8
Bias current bit 7
Bias current bit 6
Bias current bit 5
Bias current bit 4
Bias current bit 3
Bias current bit 2
Bias current bit 1
Bias current bit 0 (LSB)
Table 12. Register Functionality
FUNCTION
Enable chip bit
1 = chip enabled. Can be toggled low to reset a fault condition.
0 = chip disabled
Photodiode current range bits
1X: up to 3080 µA / 3 µA resolution
01: up to 1540 µA / 1.5 µA resolution
00: up to 770 µA / 0.75 µA resolution
Open loop enable bit
1 = open loop bias current control
0 = closed loop bias current control
Fault detection enable bit
1 = fault detection on
0 = fault detection off
Output polarity switch bit
1: pins 20 and 21 = MOD– and pins 22 and 23 = MOD+
0: pins 20 and 21 = MOD+ and pins 22 and 23 = MOD–
Equalizer enable bit
1 = equalizer enabled
0 = equalizer disabled
Photodiode polarity bit
1 = photodiode cathode connected to V_CC
0 = photodiode anode connected to GND
Offset cancellation disable bit
1 = DC offset cancellation is disabled and cross point adjust is enabled
0 = DC offset cancellation is enabled and cross point adjust is disabled
Bias current polarity bit
1 = Bias pin sources current
0 = Bias pin sinks current
Cross point adjustment range bits:
Minimum adjustment range for 00
Maximum adjustment range for 11
Modulation current setting
Modulation current: 85 mA / 83 µA steps
Closed loop (APC)
Coupling ratio CR = I_BIAS / I_PD, BIASC = 0...1023, I_BIAS ≤ 100 mA
PDRNG = 00 (see Photodiode current range bits); I_BIAS = 0.75 µA × CR × BIASC
PDRNG = 01 (see Photodiode current range bits); I_BIAS = 1.5 µA × CR × BIASC
PDRNG = 1X (see Photodiode current range bits); I_BIAS = 3 µA × CR × BIASC
Open loop
I_BIAS = 98 µA × BIASC
Copyright © 2008, Texas Instruments Incorporated
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