Datasheet

cui.com
date 11/07/2014 │ page 23 of 36CUI Inc │ SERIES: NQB-D │ DESCRIPTION: FULLY REGULATED ADVANCED BUS CONVERTERS
The product includes current limiting circuitry for
protection at continuous overload. The default setting for
the product is hic-up mode if the maximum output current
is exceeded and the output voltage is below 0.3×V
out
, set
in command IOUT_OC_LV_FAULT_LIMIT (0x48). Above
the trip voltage value in command 0x48 the product will
continue operate while maintaining the output current at
the value set by IOUT_OC_FAULT_LIMIT (0x46). The load
distribution should be designed for the maximum output
short circuit current specied.
Droop Load Share variants (DLS) will enter hic-up mode,
with a trip voltage, 0.04×V
out
, set in command IOUT_
OC_LV_FAULT_LIMIT (0x48). Above the trip voltage in
command (0x48) the product will continue operate while
maintaining the output current at the value set by IOUT_
OC_FAULT_LIMIT (0x46).
The over current protection of the product can be
recongured using the PMBus interface.
Over Current Protection (OCP)
The input of the product can be protected from high input
voltage and low input voltage. The over/under-voltage
fault level and fault response can be congured via the
PMBus interface.
Input Over/Under voltage protection
The product has a Pre-bias start up functionality and will
not sink current during start up if a Pre-bias source is
present at the output terminals. If the Pre-bias voltage
is lower than the target value set in VOUT_COMMAND
(0x21), the product will ramp up to the target value. If
the Pre-bias voltage is higher than the target value set in
VOUT_COMMAND (0x21), the product will ramp down to
the target value and in this case sink current for a limited
of time set in the command TOFF_MAX_WARN_LIMIT
(0x66).
Pre-bias Start-up Capability
The product provides Power Good (PG) ag in the Status
Word register that indicates the output voltage is within a
specied tolerance of its target level and no fault condition
exists. If specied in section Connections, the product
also provides a PG signal output. The Power Good signal
is by default congured as active low, Push-pull and can
be re-congured via the PMBus interface. The Power Good
output can be congured as Push-pull or “High Z when
active” to permit AND’ing of parallel devices. It is not
recommended to use Push-pull when paralleling PG-pins,
see MFR_MULTI_PIN_CONFIG.
Power Good
This product does not support synchronization, tracking or
external reference.
Synchronization, Tracking and External reference
The switching frequency is set to 140 kHz as default but
this can be recongured via the PMBus interface. The
product is optimized at this frequency but can run at
lower and higher frequency, (125-150 kHz). The electrical
performance can be affected if the switching frequency is
changed.
Switching frequency adjust using PMBus
The MFR_MULTI_PIN_CONFIG (0xF9) command enables
or disables different functions inside the product. This
command can be congured according to the table for
different functions.
MFR_MULTI_PIN_CONFIG
Bit 7:6
00 = Stand alone
01 = Slave (N/A)
10 = DLS
11 = Master (N/A)
1 1 1 1 1 1 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
Bit 5
Power Good High Z
when active
0 0 0 0 1 1 0 0 0 0 1 1
Bit 4
Tracking enable
(N/A)
0 0 0 0 0 0 0 0 0 0 0 0
Bit 3
External reference
(N/A)
0 0 0 0 0 0 0 0 0 0 0 0
Bit 2
Power Good
Enable
0 0 1 1 1 1 0 0 1 1 1 1
Bit 1
Reserved
1 1 1 1 1 1 0 0 0 0 0 0
Bit 0
Secondary Remote
Control Pull
up/down resistor
enable 1)
0 1 0 1 0 1 0 1 0 1 0 1
1) When not used
with PMBus, the
CTRL input can be
internally pulled up
or down depending
on if it is active high
or low. When active
low it will be pulled
up and vice versa
DLS, PMBus Control (0x82)
DLS, Sec RC w
/
pull up/down (0x83)
DLS, Power Good Push-pull, PMBus Control
(0x86) DLS, Power Good Push-pull,
Sec RC w/ pull up/down (0x87) DLS, Power Good High Z when active, PMBus Control (0xA6) DLS, Power Good High Z when active, Sec RC w/ pull up/down (0xA7) Stand alone, PMBus Control (0x00)
Stand alone, Sec RC w/ pull up/down (0x01) Stand alone, Power Good Push-pull, PMBus
Control (0x04)
Stand alone, Power Good Push-pull,
Sec RC w/ pull up/down (0x05) Stand alone, Power Good High Z when active, PMBus Control (0x24)
Stand alone, Power Good High Z when active, Sec RC w/ pull up/down (0x25)
The MFR_MULTI_PIN_CONFIG can be recongured using
the PMBus interface. Default conguration is set to Power
Good Push-Pull (0x04) for stand alone variants and DLS
Power Good Push-Pull (0x86) for Droop Load Share
variants.
This product has two data storage set: Default data (CUI
factory) and User data. The User data set’s priority is
higher than the Default data. The User data area is empty
while shipped to customer. After boot-up, if the controller
found no data stored in User data area, it will load Default
data instead.
Customer can change the RAM data and store the changes
into ash memory by PMBUS Store_User_All, next power
cycle will load the User data into RAM for execute.
Store_Default_All is write protected to ensure the factory
settings is always available for recovery.
User customized settings
For more information, please visit the product page.