LMZ10504EXT Datasheet, PDF (10/22 Pages) National Semiconductor (TI) – 4A SIMPLE SWITCHER® Power Module with 5.5V Maximum Input Voltage for Military and Rugged Applications

TABLE 1. Recommended Output Filter Capacitors
C_O (µF)
22
47
47
47
100
100
100
150
330
470
Voltage (V), R_ESR (mΩ)
6.3, < 5
6.3, < 5
6.3, < 5
10.0, < 5
6.3, < 5
6.3, 50
6.3, 25
6.3, 18
6.3, 18
6.3, 23
Make
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Tantalum
Organic Polymer
Organic Polymer
Organic Polymer
Niobium Oxide
Manufacturer
TDK
TDK
TDK
TDK
TDK
AVX
Sanyo
Sanyo
Sanyo
AVX
Part Number
Case Size
C3216X5R0J226M
1206
C3216X5R0J476M
1206
C3225X5R0J476M
1210
C3225X5R1A476M
1210
C3225X5R0J107M
1210
TPSD157M006#0050 D, 7.5 x 4.3 x 2.9 mm
6TPE100MPB2 B2, 3.5 x 2.8 x 1.9 mm
6TPE150MIC2 C2, 6.0 x 3.2 x 1.8 mm
6TPE330MIL
D3L, 7.3 x 4.3 x 2.8 mm
NOME37M006#0023 E, 7.3 x 4.3 x 4.1 mm
Output Voltage Setting
A resistor divider network from V_OUT to the FB pin determines
the desired output voltage as follows:
optimized area of operation is 30° to 60° of phase margin, with
a bandwidth of 100 kHz ±20 kHz.
R_fbt is defined based on the voltage loop requirements and
R_fbb is then selected for the desired output voltage. Resistors
are normally selected as 0.5% or 1% tolerance. Higher accu-
racy resistors such as 0.1% are also available.
The feedback voltage (at V_OUT = 2.5V) is accurate to within
-2.5% / +2.5% over temperature and over line and load reg-
ulation. Additionally, the LMZ10504EXT contains error nulling
circuitry to substantially eliminate the feedback voltage vari-
ation over temperature as well as the long term aging effects
of the internal amplifiers. In addition the zero nulling circuit
dramatically reduces the 1/f noise of the bandgap amplifier
and reference. The manifestation of this circuit action is that
the duty cycle will have two slightly different but distinct op-
erating points, each evident every other switching cycle.
Loop Compensation
The LMZ10504EXT preserves flexibility by integrating the
control components around the internal error amplifier while
utilizing three small external compensation components from
V_OUT to FB. An integrated type II (two pole, one zero) voltage-
mode compensation network is featured. To ensure stability,
an external resistor and small value capacitor can be added
across the upper feedback resistor as a pole-zero pair to
complete a type III (three pole, two zero) compensation net-
work. The compensation components recommended in Table
2 provide type III compensation at an optimal control loop
performance. The typical phase margin is 45° with a band-
width of 80 kHz. Calculated output capacitance values not
listed in Table 2 should be verified before designing into pro-
duction. A detailed application note is available to provide
verification support, AN-2013. In general, calculated output
capacitance values below the suggested value will have re-
duced phase margin and higher control loop bandwidth. Out-
put capacitance values above the suggested values will
experience a lower bandwidth and increased phase margin.
Higher bandwidth is associated with faster system response
to sudden changes such as load transients. Phase margin
changes the characteristics of the response. Lower phase
margin is associated with underdamped ringing and higher
phase margin is associated with overdamped response. Los-
ing all phase margin will cause the system to be unstable; an
30118448
TABLE 2. LMZ10504EXT Compensation Component
Values
V_IN C_O (µF) _{ESR (mΩ)}
R_fbt C_comp R_comp
(V)
Min Max (kΩ) ^(pF) (kΩ)
22
2 20 200 27 1.5
47
2 20 124 56 1.4
100
1
10 82.5 120
1
150
5.0
150
1
5 63.4 180 1.21
10 25 63.4 220 16.5
150
26 50 44.2 220 23.7
220
15 30 63.4 220 23.7
220
31 60 76.8 220 57.6
22
2 20 118 39 9.09
47
2 20 76.8 82 8.45
100
1 10 49.9 180 4.12
150
3.3
150
1
5 40.2 330 2.0
10 25 43.2 330 11.5
150
26 50 49.9 270 25.5
220
15 30 40.2 390 15.4
220
31 60 48.7 330 35.7
Note: In the special case where the output voltage is 0.8V, it is recom-
mended to remove R_fbb and keep R_fbt, R_comp, and C_comp for a type III
compensation.
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