NQ10W50PKA07 Datasheet, PDF (11/14 Pages) SynQor Worldwide Headquarters – SMT Surface Mount Package

Technical Specification
Input: 10.2 - 13.2V
Outputs: 0.7 - 5.0V
Current: 7A
Package: SMT
Continuous vs Discontinuous Conduction Modes: Table 1
summarizes the difference among the converter versions.
Referring to the last 3 digits of the part number, the QS1 and QS2
versions are configured to enable discontinuous conduction mode
(DCM) operation at light loads, whereas the QS3 and QS4 ver-
sions force continuous conduction mode (CCM) operation. Table
2 shows the typical load current corresponding to the boundary
for light-load discontinuous operation.
Version
QS1
QS2
QS3
QS4
Vref
0.7V
VSET pin
VSET pin
0.6V
Light-Load Operating Mode
Discontinuous (DCM) Enabled
Discontinuous (DCM) Enabled
Forced Continuous (CCM)
Forced Continuous (CCM)
Table 1: Version differences
Following are the main performance differences between the two
versions:
1) Current-sinking: A DCM version (QS1, QS2) will not sink cur-
rent if its output is backdriven, whereas a CCM version will sink
current as needed to regulate its output voltage, though such neg-
ative current might be limited to a few amps but may exceed
10Amps. Since this is not a normal operating condition, the neg-
ative current limit is not specified.
2) Light-load input power: The main advantage of DCM opera-
tion is lower input current at light loads, down to only about 4 mil-
liamps with no-load (for all input/output voltage conditions). The
efficiency improvement of the DCM version only becomes evident
as the load is reduced below 1.5A for a 5.0V output. This thresh-
old gradually falls to about 1 Amp at 2.5V and 0.75A at 0.7V,
as shown in Table 2 below.
3) Light-load output ripple: The output ripple of the DCM version
has a higher amplitude, as well as a significant amount of low-fre-
quency content at light loads (as low as 200Hz for 0.7Vout at no-
load). With the same output capacitance, peak-to-peak output
voltage ripple at light-loads may be 3 to 10 times as large for
DCM as for the CCM version. At heavier loads, all versions oper-
ate in continuous conduction and have very low output voltage
ripple.
4) Transient response: The CCM version has a better response to
dynamic loads. The output voltage deviation, while excellent on
both versions, is about 20% lower on the CCM version. With a
falling load step, a longer settling time may also be noticeable,
especially when stepping into very light loads, as there is no cur-
rent sinking capability to quickly reduce the output voltage from
its peak deviation.
5) No-Load Regulation: When operating in discontinuous mode
with extremely light loads (<50mA), the output voltage may rise
by 1 to 2% beyond the specified tolerance.
Output Voltage Boundary Current Efficiency Advantage
Setpoint
for Output Ripple Boundary Current
0.7V - 1.8V
2.0 Amps
0.75Amps
2.5V
2.2 Amps
1.0 Amps
3.3V
2.4 Amps
1.2 Amps
5.0V
2.6 Amps
1.5 Amps
Table 2: Boundary currents below which DCM operation
increases ripple and improves efficiency
Setting Output Voltage (VADJ, pin 11): This converter is a
wide-output module and requires external resistors R₁ and R₂ (see
Figure 17) to set the output voltage. The output voltage is set by
the ratio between R₁ and R₂ in parallel with an internal 100K
resistor as follows:
V_out = V_{ref *} [1 + (R₂ || 100K) / R₁]
where Vref is given in Table 1 above. In terms of the top resistor
R₂, the trim equation is:
R₂ ^{= (Vout - Vref) * R1 * 100K}
V_{ref *} (R₁ + 100K) - V_{out *} R₁
The recommended value for bottom resistor R₁ is 1.0K.
Significantly larger values of R₁ will degrade the DC accuracy of
the remote sensing, particularly with high output voltages where
the trim resistor R₂ becomes comparable to the internal 100K par-
allel resistor. If remote sensing is not used, larger values of R₁ up
to 5.0K may be used.
With R₁=1K
R₂ (in kohm) =
(V_out - V_ref) _* 100
101 _* V_ref - V_out
Total DC Variation of Vout: For the converter to meet its spec-
ifications, the maximum variation of the DC value of the convert-
er output voltage, due to voltage adjustment, margining, and
remote load voltage drops, should not be greater than that spec-
ified for the output voltage trim range.
Differential Remote Sense: Using the differential remote
sense feature, the converter can be configured to adjust its output
voltage up to compensate for resistive drops between the con-
verter and the load. Differential remote sensing is achieved by a
Kelvin connection of the top trim resistor R₂ (see Figure 17) and
the CTRL GND pin respectively to the Vout and common rails at
the desired remote location. The other end of R₂ connects to the
VADJ pin, and the bottom trim resistor R₁ connects between the
Product # NQ10W50PKA07
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Doc.# 005-2NS2T5N Rev. B 6/12/07
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