Max3798 – Rainbow Electronics MAX3798 User Manual
Page 24
MAX3798
Transmitter Control Register (TXCTRL)
Bit 3: TXDE_EN. Enables or disables the transmit output deemphasis circuitry.
0 = disabled
1 = enabled
Bit 2: SOFTRES. Resets all registers to their default values.
0 = normal
1 = reset
Bit 1: TX_POL. Controls the polarity of the transmit signal path.
0 = inverse
1 = normal
Bit 0: TX_EN. Enables or disables the transmit circuitry.
0 = disabled
1 = enabled
Transmitter Status Register 1 (TXSTAT1)
Bit 7: FST[7]. When the V
CCT
supply voltage is below 2.45V, the POR circuitry reports a FAULT. Once the V
CCT
supply voltage is above 2.55V, the POR resets all registers to their default values and the FAULT is cleared.
Bit 6: FST[6]. When the voltage at BMON is above V
CC
- 0.55V, a SOFT FAULT is reported.
Bit 5: FST[5]. When the voltage at MMAX goes below V
CC
- 0.65V, a HARD FAULT is reported.
Bit 4: FST[4]. When the voltage at BMAX goes below V
CC
- 0.65V, a HARD FAULT is reported.
Bit 3: FST[3]. When the common-mode voltage at V
TOUT
+/- goes below 1.5V, a SOFT FAULT is reported.
Bit 2: FST[2]. When the voltage at V
TOUT
+/- goes below 0.8V, a HARD FAULT is reported.
Bit 1: FST[1]. When the BIAS voltage goes below 0.44V, a HARD FAULT is reported.
Bit 0: TX_FAULT. Copy of a FAULT signal in FST[7] to FST[1]. A POR resets FST[7:1] to 0.
Transmitter Status Register 2 (TXSTAT2)
Bit 3: IMODERR. When the modulation-incremented result is greater than IMODMAX, a SOFT FAULT is reported.
(See the
Programming Modulation Current
section.)
1.0625Gbps to 10.32Gbps, Integrated, Low-
Power SFP+ Limiting Amplifier and VCSEL Driver
24
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Bit #
7
(STICKY)
6
(STICKY)
5
(STICKY)
4
(STICKY)
3
(STICKY)
2
(STICKY)
1
(STICKY)
0
(STICKY)
ADDRESS
Name
FST[7] FST[6] FST[5] FST[5] FST[3] FST[2] FST[1]
TX_FAULT
Default
Value
X X X X X X X X
H0x06
Bit #
7
6 5 4
3
(STICKY)
2
(STICKY)
1
(STICKY)
0
(STICKY)
ADDRESS
Name
X X X X
IMODERR
IBIASERR
TXED
X
Default
Value
X X X X X X X X
H0x07
Bit #
7 6 5 4 3 2 1 0
ADDRESS
Name X
X
X
X
TXDE_EN
SOFTRES
TX_POL
TX_EN
Default
Value
X X X X 0 0 1 1
H0x05