Rules For Building An Sr System - Philips Xitanium LED Xtreme SR Design-In Manual

SR built-in supply typical VI curve
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Design-in Guide - Philips Xitanium LED Xtreme SR driver
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Current [mA]

Rules for building an SR system

• SR (DA+/DA-) bus polarity must be respected when more
than one SR supply is connected in parallel.
• The total maximum SR bus current (ISR_MAX_TOTAL) must
not exceed 250 mA. This current can be determined by adding
up ISR_MAX of all connected SR supplies. As a consequence a
maximum of four SR supplies can be connected in parallel.
• The total current delivered to the SR bus (ISR_DELIVERED)
can be determined by adding ISR of all connected SR supplies.
55 60
• The total current extracted from the SR bus
(ISR_EXTRACTED) can be determined by adding up
consuming devices like SR drivers with switched OFF SR
supply, other DALI gear and control devices.
• To guarantee good communication, a margin of 8 mA is needed
to drive the SR bus itself (ISR_MARGIN).
• The following rule should be respected:
ISR_EXTRACTED + ISR_MARGIN ≤ ISR_DELIVERED.
Caution:
When the above rules are not taken into account,
communication cannot be guaranteed and damage to
components may occur.
Typical examples
1. One SR driver is connected to a control device. The internal
SR supply of this driver is switched ON. The specification of
the control device states that the extracted peak current is
40 mA. Will this SR system have good communication?
• One SR supply is involved, so BUS polarity is irrelevant.
• ISR_MAX_TOTAL = 60 mA. This is ≤ 250 mA
• ISR_DELIVERED = 52 mA
• ISR_EXTRACTED = 40 mA
• ISR_MARGIN = 8 mA
• 40 + 8 mA ≤ 52 mA
This system will function properly.
2. Is it allowed to add an SR driver with switched OFF SR supply
to this SR system?
Yes, an SR driver with switched OFF SR supply extracts 2 mA
from the SR bus.
• ISR_EXTRACTED = 40 + 2 = 42 mA.
• 42 + 8 mA ≤ 52 mA
This system will function properly.
3. Can this SR supply also be switched on?
Yes, but the polarity of both SR supplies should be verified.
• ISR_TOTAL = 2 * 60 = 120 mA. This is ≤ 250 mA.
This system will function properly.
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