EVALA5970D STMicroelectronics, EVALA5970D Datasheet - Page 18

• Manufacturer Part Number: EVALA5970D
• Description: Power Management Modules & Development Tools EVAL BOARD A5970D Auto Grade
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVALA5970D

• Input Voltage: 4.4 V to 36 V
• Output Voltage: 1.235 V to 35 V
• Board Size: 23 mm x 20 mm
• Product: Power Management Modules
• Supply Current: 1 A
• Dimensions: 23 mm x 20 mm
• For Use With/related Products: AN1330
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application information
18/31
Nevertheless, the ESR of the output capacitor introduces a zero in the open loop gain,
which helps to increase the phase margin of the system. If the zero goes to a very high
frequency, its effect is negligible. For this reason, ceramic capacitors and very low ESR
capacitors in general should be avoided.
Tantalum and electrolytic capacitors are usually a good choice for this purpose.
Table 3
Table 3.
1. POSCAP capacitors have characteristic very similar to tantalum capacitors.
●
The inductor value is very important because it fixes the ripple current flowing through
output capacitor.
The ripple current is usually fixed at 20-40% of I
The approximate inductor value is obtained using the following formula:
Equation 19
where T
For example, with V
35 µH.
The peak current through the inductor is given by:
Equation 20
and it can be observed that if the inductor value decreases, the peak current (which must be
lower than the current limit of the device) increases. So, when the peak current is fixed, a
higher inductor value allows a higher value for the output current.
In
Table 4.
AVX
KEMET
Sanyo POSCAP
Sprague
Coilcraft
Table 4: Inductor
Manufacturer
Inductor
Manufacturer
below provides a list of some tantalum capacitor manufacturers.
ON
is the ON time of the internal switch, given by D · T.
Output capacitor selection
Inductor selection
(1)
OUT
selection, some inductor manufacturers are listed.
= 3.3 V, V
TPA/B/C
T494/5
Series
595D
TPS
DO1813HC
DO3316
Series
L
IN
=
= 12 V and ∆I
(
-------------------------------------- -
V IN V OUT
I PK
Cap value (µF)
–
100 to 470
100 to 470
100 to 470
220 to 390
I ∆
=
I O
O
Inductor value (µH)
max, which is 0.2 - 0.4 A with I
+
O
I ∆
---- -
)
2
= 0.3 A, the inductor value is about
•
22 to 33
33 to 47
T
ON
Rated voltage (V)
4 to 35
4 to 20
4 to 16
4 to 20
Saturation current (A)
1 to 1.2
1.6 to 2
ESR (mΩ)
160 to 650
50 to 200
30 to 200
O
40 to 80
max = 1 A.
AN1330