MAX-7 / NEO-7 / LEA-7 - Hardware Integration Manual
GPS.G7-HW-11006-1
Hardware description
Page 12 of 55
Name Component
Function
Comments
U1
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/GNSS receiver is operated as
a USB self-powered device, but if bus-powered LDO (U1) must be able to
deliver the maximum current. For the peak supply current, see a low-cost
DC/DC converter such as LTC3410 from Linear Technology.
C23,
C24
Capacitors
Required according to the specification of LDO U1
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
Ω
A value of 27
Ω
is recommended.
R11
Resistor
1 k
Ω
is recommended for USB self-powered setup. For bus-powered setup,
R11 can be ignored.
Table 2: Summary of USB external components