AMY-6M - Hardware Integration Manual
UBX-17021971 – R07
Design-in
Page 18 of 57
The AMY-6M can be either bus-powered or self-powered. Bus-powered means the AMY-6M is supplied by the
VBUS voltage from the USB. Self-powered means the AMY-6M is powered by another supply independent from
VBUS supply and just the USB interface VDD_USB is supplied by VBUS (through an LDO (U4)).
Depending on the characteristics of the LDO (U4) it is recommended to add a pull-down resistor (R11) at its
output to ensure
VDD_USB
is not floating if LDO (U4) is disabled or the USB cable is not connected i.e. VBUS is
not supplied.
All u-blox 6 receivers support both Bus and Self Powered Mode on the USB interface. Please be sure to use the
latest drivers from our website.
Connect
VDD_USB
to GND if not used.
With config pin CFG_COM0 the AMY-6M can be set to Bus (CFG_COM1=open) or Self Powered
(CFG_COM1=GND)
USB is not compatible with Power Save Mode with FW6.02 and below
Figure 11: USB Interface (bus powered setup)
Name
Component
Function
Comments
U4
LDO
Regulates VBUS (4.4 …5.25 V)
down to a voltage of 3.3 V.
Almost no current requirement (~1 mA) if the GPS receiver is operated as a USB
self-powered device, but if bus-powered LDO (U4) must be able to deliver the
maximum current of ~70 mA. A low-cost DC/DC converter such as LTC3410
from Linear Technology may be used as an alternative.
C23,
C24
Capacitors
Required according to the specification of LDO U4
D2
Protection
diodes
Protect circuit from overvoltage
/ ESD when connecting.
Use low capacitance ESD protection such as ST Microelectronics USBLC6-2.
R4, R5 Serial
termination
resistors
Establish a full-speed driver
impedance of 28…44 Ohms
A value of 22 Ohms is recommended.
R11
Resistor
Ensures a pull down when LDO
is disabled.
1k Ohms is recommended for USB self-powered setup. For bus-powered setup
R11 is not required.
FB1
Ferrite Bead
Filters Noise at GPS frequency
Table 5: Summary of USB external components