ETAS ES4435.1, Руководство пользователя

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ES4435.1 Current Source Load Board - User’s Guide 11
ETAS Hardware
2 Hardware
This chapter describes the individual function units of the ES4435.1 Current
Source Load Board in more detail.
These are:
• "Current Sources" on page 11
• "Configuration in LABCAR-RTC" on page 12
• "Assigning “Load in Slot x” to Connector “Load n”" on page 13
• "The Load Signals at the Backplane Connectors" on page 14
2.1 Current Sources
The current sources of the ES4435.1 Current Source Load Board are controlled
MOSFET current sources for regulating current – the input operational amplifier
is addressed via a 10-bit D/A converter with a serial input.
Mechanical relays control the pull functionality.
Operation Modes “Pull-Up” and “Pull-Down”
In the operation mode “pull-up”, the current source is switched internally
against the positive potential of the selected battery node. A current flows from
the source when the load is connected to an ECU pin with lower potential (e.g.
-UBatt).
In the operation mode “pull-down”, the current source is switched internally
against the negative potential (-UBatt). A current flows into the source when the
load is connected to an ECU pin with higher potential.
2.1.1 Currents
The maximum power of the current sources is 3 W. For the maximum current
rating of the current sources, this means:
• 150 mA (pull-up/pull-down) with a battery voltage of 6..20 V
• 70 mA with a battery voltage of 20..42 V
• 50 mA with a battery voltage of 42..60 V
with an accuracy of 3 mA.
2.1.2 Switched Battery Voltages
All current sources must refer to switched battery voltages in their pull-up func-
tion, i.e. the corresponding current source only becomes active when the corre-
sponding battery node is activated.
The battery node control signals are TTL signals which are applied from the
ES4408CON.1 Communication Interface to the backplane of the ES4408.1 Load
Chassis.
Note
The ES4435.1 Current Source Load Board can only be operated in connection
with LABCAR-RTC! Otherwise, leakage currents of the MOSFETs can lead to
signal problems as the relevant source is disabled but configured as pull-down.
If the ES4435.1 is disabled in LABCAR-RTC, these problems do not occur.