NQ12T50SMA16 Datasheet, PDF (12/15 Pages) SynQor Worldwide Headquarters – 16A Non-Isolated, SMT DC/DC Converter with wide trim

Technical Specification
Non-Isolated
SMT Converter
9.6 - 14.4Vin 16A
information.
Output Capacitance: It is recommended to add at least
100µF of capacitance, with an ESR in the 0.1W range, to the
output of the SMA16 series of converters. The VMA16 series
has this capacitance included internally. In many applications,
however, additional external output capacitance is required to
reduce the response to load transients to an allowable level.
The output impedance of these converters can be quite accu-
rately modeled from DC to about 100kHz as shown in Figure
D. A further simplified version of it, valid below 40Hz and
above 1kHz, is shown
in Figure E. In the
SMA16 case, the mod-
els depict the minimum
recommended output
capacitance, Ct with its
resistance Rt. In the
VMA16 family, that
capacitor is again
included in the convert-
er.
Figure D: NQ12 Passive Output Model
If the dynamic char-
acteristics of the load
are known, any stan-
dard simulator can
use these models to
predict the in-circuit
transient response.
If the transients are
Figure E: Simplified NQ12 Output Model ^{current steps then}
Table 3 provides
values for ESRd and Cd for different allowable responses. The
allowable step response is normalized to a 1A step, and the
maximum allowable value of ESRd can be read from the table.
Figure F: Converter with Additional Output Capacitance
For minimal overshoot upon recovery, Cd should be related to
the minimum in-circuit net ESR.
Cd > ^{parallel (L1, L2)}
ESRd_min²
The third column in Table 3 gives Cdmin for a 40% reduction
in ESR and the highest L1||L2 value in Table 2. For more
detailed derivations of these values, contact SynQor technical
support.
Load Current
Step Response
Pk mV/Amp
23
19
14
9
5
External Capacitor
ESRd max
0.1*
0.05
0.025
0.0125
0.00625
Cd min (uF)
100*
400
1,600
6,400
25,600
* Included in VMA, min recommended for SMA
Table 3: External Capacitor Values for Different Step Responses
Thermal Performance (SMA16): While it's impossible to
be exact, a simplified thermal model for the mounted converter
is detailed below.
Table 2: Component Values for Passive Output Models
Product # NQ12T50SMA16
Phone [phone]
Figure G: Thermal Model for NQ12 Surface Mount
• Rt_J-Pcb models the conduction of heat from the converter's
Doc.# 005-2NS12TE Rev. A
5/28/04
Page 12