Linear Technology LTC6804-1 - Page 74

LTC6804-1/LTC6804-2
74
680412fc
For more information www.linear.com/LTC6804-1
Transformer Selection Guide
As shown in Figure 41, a transformer or pair of transform-
ers isolates the isoSPI signals between two isoSPI ports.
The isoSPI signals have programmable pulse amplitudes
up to
1.6V
P-P
and pulse widths of 50ns and 150ns. To be
able to transmit these pulses with the necessary fidelity
the system requires that the transformers have primary
inductances above 60µH and a 1:1 turns ratio. It is also
necessary to use a transformer with less than 2.5µH of
leakage inductance. In terms of pulse shape the primary
inductance will mostly effect the pulse droop of the 50ns
and 150ns pulses. If the primary inductance is too low,
the pulse amplitude will begin to droop and decay over
the pulse period. When the pulse droop is severe enough,
the effective pulse width seen by the receiver will drop
substantially, reducing noise margin. Some droop is ac
-
ceptable as long as it is a relatively small percentage of
applicaTions inForMaTion
the total pulse amplitude. The leakage inductance primarily
affects the rise and fall times of the pulses. Slower rise
and fall times will effectively reduce the pulse width. Pulse
width is determined by the receiver as the time the signal
is above the threshold set at the ICMP pin. Slow rise and
fall times cut into the timing margins. Generally it is best
to keep pulse edges as fast as possible. When evaluating
transformers, it is also worth noting the parallel winding
capacitance. While transformers have very good CMRR at
low frequency, this rejection will degrade at higher frequen
-
cies, largely due to the winding to winding capacitance.
When choosing a transformer, it is best to pick one with
less parallel winding capacitance when possible.
When choosing a transformer
, it is equally important to
pick a part that has an adequate isolation rating for the
application. The working voltage rating of a transformer
is a key spec when selecting a part for an application.
Table48. Recommended Transformers
MANUFACTURER PART NUMBER
TEMPERATURE
RANGE V
WORKING
V
HIPOT
/60s CT CMC H L
W
(W/LEADS) PINS
AEC–
Q200
Dual Transformers
Pulse HX1188FNL –40°C to 85°C 60V (est) 1.5kVrms
l l
6.0mm 12.7mm 9.7mm 16SMT –
Pulse HX0068ANL –40°C to 85°C 60V (est) 1.5kVrms
l l
2.1mm 12.7mm 9.7mm 16SMT –
Pulse HM2100NL –40°C to 105°C 1000V 4.3kVdc –
l
3.4mm 14.7mm 14.9mm 10SMT
l
Pulse HM2102NL –40°C to 125°C 1000V 4.3kVdc
l l
4.9mm 14.8mm 14.7mm 12SMT
l
Sumida CLP178–C20114 –40°C to 125°C 1000V (est) 3.75kVrms
l l
9mm 17.5mm 15.1mm 12SMT –
Sumida CLP0612–C20115 600Vrms 3.75kVrms
l
– 5.7mm 12.7mm 9.4mm 16SMT –
Wurth Elektronik 7490140110 –40°C to 85°C 250Vrms 4kVrms
l l
10.9mm 24.6mm 17.0mm 16SMT –
Wurth Elektronik 7490140111 0°C to 70°C 1000V (est) 4.5kVrms
l
– 8.4mm 17.1mm 15.2mm 12SMT –
Wurth Elektronik 749014018 0°C to 70°C 250Vrms 4kVrms
l l
8.4mm 17.1mm 15.2mm 12SMT –
Halo TG110–AE050N5LF –40°C to 85/125°C 60V (est) 1.5kVrms
l l
6.4mm 12.7mm 9.5mm 16SMT
l
Single Transformers
Pulse PE–68386NL –40°C to 130°C 60V (est) 1.5kVdc – – 2.5mm 6.7mm 8.6mm 6SMT –
Pulse HM2101NL –40°C to 105°C 1000V 4.3kVdc –
l
5.7mm 7.6mm 9.3mm 6SMT
l
Wurth Elektronik 750340848 –40°C to 105°C 250V 3kVrms – – 2.2mm 4.4mm 9.1mm 4SMT –
Halo TGR04–6506V6LF –40°C to 125°C 300V 3kVrms
l
– 10mm 9.5mm 12.1mm 6SMT –
Halo TGR04–A6506NA6NL –40°C to 125°C 300V 3kVrms
l
– 9.4mm 8.9mm 12.1mm 6SMT
l
TDK ALT4532V–201–T001 –40°C to 105°C 60V (est) ~1kV
l
– 2.9mm 3.2mm 4.5mm 6SMT
l
Halo TDR04–A550ALLF –40°C to 105°C 1000V 5kVrms
l
– 6.4mm 8.9mm 16.6mm 6TH
l
Sumida CEEH96BNP–LTC6804/11 –40°C to 125°C 600V 2.5kVrms – – 7mm 9.2mm 12.0mm 4SMT –
Sumida CEP99NP–LTC6804 –40°C to 125°C 600V 2.5kVrms
l
– 10mm 9.2mm 12.0mm 8SMT –
Sumida ESMIT–4180/A –40°C to 105°C 250Vrms 3kVrms – – 3.5mm 5.2mm 9.1mm 4SMT
l
TDK VGT10/9EE–204S2P4 –40°C to 125°C 250V (est) 2.8kVrms
l
– 10.6mm 10.4mm 12.7mm 8SMT –