JMM-5000 User Manual Rev B.01
Page 9
4. POWER SUPPLY OPERATION
4.1
Source Selection
The power supply takes its input from either the main input connector or the optional backup / battery input
connector, with precedence given to the main input connector. If the input voltage on the main input connector is
above the designated threshold voltage, it will be used as the source for the power supply. If the input voltage falls
below the minimum, the supply will automatically switch to the backup / battery input. If this secondary input does
not have sufficient voltage, the supply will shut off.
The design supports the use of either single or dual power sources using the LTC4417 chip.
4.2
+5V Output Functionality
The +5V output uses a multi-phase design. The 5V is generated from a dual LTC3890 switch. Each switch output
can produce up to 5A of output current for a total of 20A capacity with all 4 outputs enabled. In this fashion the
output efficiency can be optimized based on the load, resulting in higher efficiency across the full rated output
power of the supply.
4.3
+12V Output Functionality
The LT3790 synchronous 4-switch buck-boost voltage/ current regulator controller is used for generating +12V
output. The current output is limited to 8A maximum.
4.4
+3.3V Output Functionality
A TI-based power module is used for generating +3.3V output at 5A maximum. The LMZ31710 is a SIMPLE
SWITCHER power module and an easy-to-use integrated power solution that combines a 10A DC/DC converter
with power MOSFETs, a shielded inductor, and passives in a low profile, QFN package. The module is powered
using the 5V supply.
4.5
+5V Standby Output Functionality
A LT8620 2A regulator is used for the +5V standby supply. The +5V standby supply is used to supply the power
controller and to generate the +3.3V standby voltage. +5V standby at 1A maximum is available at the output
connector.
4.6
+3.3V Standby Output Functionality
The AP7167-SPG-13 is used for generating the +3.3V standby supply. The +3.3V standby supply is used to supply
the PIC microcontroller and the USB to I2C chip. 3.3V standby 0.1A maximum is available at the output connector.
4.7
Input Protection
JMM-5000 includes an input protection circuit based on the LTC4364 chip. This device provides surge / spike
protection, load dump protection, overvoltage / under voltage protection, reverse polarity protection, and input
current limiting (circuit breaker). Filtering is also added to limit noise reflected back onto the input.