Technical Specification
Non-Isolated
SIP Converter
3.0 - 5.5V
16A
in
between Pin 10 (TRIM) and the Common Ground Pins. To
acheive a desired output voltage Vout, the value of the resistor
should be:
BASIC OPERATION AND FEATURES
The NiQor series non-isolated converter uses a buck-converter
that keeps the output voltage constant over variations in line,
load, and temperature. The NiQor modules employ synchro-
nous rectification for very high efficiency.
21070
_
=
(Ω)
Rtrim
5110
_
VOUT 0.7525
Dissipation throughout the converter is so low that it does not
require a heatsink or metal baseplate for operation. The NiQor
converter can thus be built more simply and reliably using high
yield surface mount techniques on a single PCB substrate.
For example, to program an output voltage of 3.3V, the Rtrim
resistor value is calculated as follows:
R
trim = (21070/(3.3-0.7525)) - 5110 = 3.16 kΩ
The NiQor series of SIPs and SMT converters uses the estab-
lished industry standard footprint and pin-out configurations.
Note: the TRIM feature does not affect the voltage at which the
output over-voltage protection circuit is triggered. Trimming the
output voltage too high may cause the over-voltage protection
circuit to engage, particularly during transients.
CONTROL FEATURES
Total DC Variation of Vout: For the converter to meet its
specifications, the maximum variation of the DC value of Vout,
due to both trimming and remote load voltage drops, should
not be greater than that specified for the output voltage trim
range.
REMOTE ON/OFF (Pin 11): The ON/OFF input, Pin 11,
permits the user to control when the converter is on or off. There
are currently two options available for the ON/OFF input
described in the table below. (contact factory for other options)
Pin-Open
Option
Description Converter state Pin Action
PROTECTION FEATURES
N Logic Negative
Off
On
On
Pull Low = On
Pull High = Off
Pull Low = Off
O Logic Negative/Open
P Logic Positive/Open
Input Under-Voltage Lockout: The converter is designed
to turn off when the input voltage is too low, helping avoid an
input system instability problem, described in more detail in the
application note titled “Input System Instability”. The lockout cir-
cuitry is a comparator with DC hysteresis. When the input volt-
age is rising, it must exceed the typical Turn-On Voltage
Threshold value (listed on the specification page) before the
converter will turn on. Once the converter is on, the input volt-
age must fall below the typical Turn-Off Voltage Threshold value
before the converter will turn off.
Figure A is a schematic view of the internal ON/OFF circuitry.
Vin
Vin
(N logic only)
10K
10K
1K
PWM
Enable
ON/OFF
ON/OFF
20K
Over Current Shutdown: The converter uses the control
(high-side) MOSFET on-resistance to detect short circuit or
excessive over-current conditions. The converter compensates
for the temperature variation of the MOSFET on-resistance,
keeping the overcurrent threshold roughly constant over tem-
perature. Very short (<1mS) over-current pulses will see a
slightly higher apparent threshold than longer duration over-
current events. This makes the converter less susceptible to shut-
down from transient load conditions. However, once the over-
current threshold is reached the converter ceases PWM opera-
tion within microseconds. After an over-current shutdown, the
converter will remain off for an inhibit period of 18 to 32 mil-
liseconds, and then attempt a soft-start. Depending on the
impedance or current level of the overload condition, the con-
verter will enter a "hiccup mode" where it repeatedly turns on
PWM
Enable
20K
15K
Negative
Logic (N,O)
Positive
Logic (P)
Figure A: Simplified Schematic of internal ON/OFF circuitry
OUTPUT VOLTAGE TRIM (Pin 10): The TRIM input permits
the user to adjust the output voltage according to the trim range
specifications by using an external resistor. If the TRIM feature
is not being used, leave the TRIM pin disconnected.
TRIM (wide trim output unit): The output voltage of the
NQ04T33 module can be programmed to any voltage from
0.85 to 3.6V by connecting a single external resistor Rtrim
Product # NQ04T33VMA16
Phone 1-888-567-9596
Doc.# 005-2NV4T3E Rev. B
7/6/04
Page 16
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