ZY1015 Datasheet, PDF (15/17 Pages) Power-One – 15A No-Bus POL 3V to 14V Input 0.5V to 5.5V Output

ZY1015 15A No-Bus POL Data Sheet
3V to 14V Input • 0.5V to 5.5V Output
9. Application Information
9.1 Output Voltage Margining
Margining can be implemented either by changing
the trim voltage as described in the previous
paragraph or by changing the resistance between
the REF and TRIM pins.
Margining
Up Switch
(normally
open)
Margining
Down Switch
(normally
closed)
R _DOWN
R _UP
R _TRIM
POL
REF
TRIM
PGND
Figure 18. Margining Configuration
In the schematic shown in Figure 18, the nominal
output voltage is set with the trim resistor R_TRIM
calculated from the equation in the paragraph 8.12.
Resistors R_UP and R_DOWN are added to margin the
output voltage up and down respectively and
determined from the equations below.
R_UP
=
20 × R_TRIM
20 + R_TRIM
×
⎜⎜⎝⎛
5
×
R_TRIM
∆V
−
%
∆V
%
⎟⎟⎠⎞
,
kΩ
R_DOWN
=
(20
+
R_TRIM
)×
⎜⎛
⎝
∆V %
100 − ∆V
%
⎟⎞
⎠
,
kΩ
where R_TRIM is the value of the trim resistor in kΩ and
∆V% is the absolute value of desired margining
expressed in percents of the nominal output voltage.
During normal operation the resistors are removed
from the circuit by the switches. The “Margining
Down” switch is normally closed shorting the resistor
R_DOWN while the “Margining Up” switch is normally
open disconnecting the resistor R_UP.
An alternative configuration of the margining circuit is
shown in Figure 19. In the configuration both
switches are normally open that may be
advantageous in some implementations.
Margining
Up Switch
(normally
open)
R _UP
R
TRIM
Margining
Down Switch
(normally
open)
R_DOWN
POL
REF
TRIM
PGND
Figure 19. Alternative Margining Configuration
R_UP and R_DOWN for this configuration are determined
from the following equations:
R_UP
=
20 × R_TRIM
20 + R_TRIM
×
⎜⎜⎝⎛
5
×
R_TRIM −
∆V %
∆V
%
⎟⎟⎠⎞
,
kΩ
R_DOWN
=
20 × R_TRIM
20 + R_TRIM
× ⎜⎛ ^{100 − ∆V %} ⎟⎞ ,
⎝ ^{∆V %} ⎠
kΩ
Caution:
Noise injected into the TRIM node may affect accuracy
of the output voltage and stability of the POL
converter. Always minimize the PCB trace length from
the TRIM pin to external components to avoid noise
pickup.
Refer to No-Bus^TM POL Converters. Z-1000 Series
Application Note on www.power-one.com for more
application information on this and other product
features.
REV. 1.2 MAR 14, 2007
www.power-one.com
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