# CW503 Probe Power Supply

![CW503.jpg](Images/CW503.jpg "CW503.jpg")

The CW503 provides a handy power supply for both the differential probe
and the LNA. Multiple probes can be connected to a single power supply.
The following shows the internal block diagram of the CW503 probe power
supply:

![image](Images/Blockdiagram.png "image")

The use of isolated DC-DC converters allows you to use connected probes
without worry about ground loops. Note the probe is *not designed* for
use at high isolation voltages (\>30V).

The power supply uses a micro-USB jack, allowing you to power the probe
from front-pane USB ports on some instruments (be careful of current
limits if using this method):

![image](Images/Diffprobe-psu.jpg "image")

Alternatively the probe comes with a high-quality 5.0V wall-wart
adapter, which has been selected for minimum noise input to the CW503.

[Datasheet](http://media.newae.com/datasheets/NAE-PBSET-PSU_datasheet.pdf)

---

## Front-Panel Connections

The following can be found on the front panel of the device:

  - Power Good LEDs:
     The probe PSU monitors the +7.8V, -7.8V, and +3.3V outputs. If
     these outputs fall below the required setpoints the LEDs
     extinguish. This is normally due to excessive current draw or a
     short on one of the output lines.
  - 6-Pin Probe PSU Connectors:
     This probe supply connectors use the same pinout as our Low Noise
     Amplifier (CW502) and Differential Probe (CW501). The pinout is as
     follows:
    
     | **Pin** | **Name**       |
     | --- | ---------- |
     | 1   | \+7.8V Out |
     | 2   | GND        |
     | 3   | Aux Out    |
     | 4   | \+3.3V Out |
     | 5   | \-7.8V Out |
     | 6   | GND        |
    
  * PROBE-GND Pin Header:
     This pin header connects to the GND pins on the 6-pin connector.

  * AUX-IN Pin Header:
     This pin header connects to the "Aux Out" pin on the 6-pin
     connector.

  * USB-GND Pin Header:
     This pin header connects to the USB negative (ground). You can
     connect this to the PROBE-GND to remove the isolation, or use a
     resistor if you want to reduce voltage differential without
     directly connecting them.