Datasheet

T
CA
<
T
J(MAX)
- T
A(MAX)
P
IC_LOSS
- T
JC
VIN
EN
GND
FB
LMZ10503EXT
R
fbt
R
comp
C
comp
R
fbb
V
IN
VOUT
LMZ10503EXT
www.ti.com SNVS668G –JUNE 2010–REVISED OCTOBER 2013
kHz. Calculated output capacitance values not listed in Table 2 should be verified before designing into
production. A detailed application note is available to provide verification support, AN-2013 SNVA419. In general,
calculated output capacitance values below the suggested value will have reduced phase margin and higher
control loop bandwidth. Output 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. Losing all phase margin will cause the system to be unstable; an optimized area of operation is 30° to
60° of phase margin, with a bandwidth of 100 kHz ±20 kHz.
Table 2. LMZ10503EXT Compensation Component Values
(1)
V
IN
(V) C
O
(µF) ESR (mΩ) R
fbt
(kΩ) C
comp
(pF) R
comp
(kΩ)
Min Max
22 2 20 143 39 8.06
47 2 20 100 100 8.25
100 1 10 71.5 180 4.32
150 1 5 56.2 270 2.1
5.0
150 10 25 59 270 10.8
150 26 50 66.5 270 23.7
220 15 30 53.6 360 14
220 31 60 59 360 30.1
22 2 20 100 56.2 5.62
47 2 20 66.5 150 5.49
100 1 10 45.3 270 2.8
150 1 5 40.2 360 1.5
3.3
150 10 25 40.2 360 7.32
150 26 50 43.2 360 15.4
220 15 30 40.2 470 10.5
220 31 60 40.2 470 20.5
(1) In the special case where the output voltage is 0.8V, it is recommended to remove R
fbb
and keep R
fbt
, R
comp
, and C
comp
for a type III
compensation.
Estimate Power Dissipation and Board Thermal Requirements
Use the current derating curves in the Typical Performance Characteristics section to obtain an estimate of
power loss (P
IC_LOSS
). For the design case of V
IN
= 5V, V
OUT
= 2.5V, I
OUT
= 3A, T
A(MAX)
= 85°C , and T
J(MAX)
=
125°C, the device must see a thermal resistance from case to ambient (θ
CA
) of less than:
(15)
(16)
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