ZY1120 Power-One, ZY1120 Datasheet - Page 15

• Manufacturer Part Number: ZY1120
• Description: Zy1120 20a No-bus Pol
• Manufacturer: Power-One

8.15 –VS and +VS
The differential voltage input of the POL converter
feedback loop.
9.
9.1
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.
In the schematic shown in Figure 18, the nominal
output voltage is set with the trim resistor R
calculated from the equation in the paragraph 8.12.
Resistors R
output voltage up and down respectively and
determined from the equations below.
where R
ΔV% is the absolute value of desired margining
expressed in percents of the nominal output voltage.
ZD-00790 REV. 1.5
Up Switch
Margining
(normally
open)
Application Information
R
112.5 and 123.75 degrees, otherwise false PG and/or OV
indications may occur.
R
Output Voltage Margining
UP
DOWN
TRIM
=
Figure 18. Margining Configuration
UP
20
20
is the value of the trim resistor in kΩ and
R
=
and R
×
+
UP
Down Switch
(
20
R
R
Margining
(normally
closed)
TRIM
TRIM
+
R
DOWN
TRIM
×
⎛
⎜ ⎜
⎝
5
R
)
are added to margin the
×
×
R
DOWN
R
⎛
⎜
⎝
TRIM
100
TRIM
Δ
V
Δ
−
%
V
−
Δ
%
Δ
REF
TRIM
PGND
V
V
%
%
⎞
⎟
⎠
www.power-one.com
⎞
⎟ ⎟
⎠
, kΩ
, kΩ
POL
TRIM
3V to 14V Input
ZY1120 20A No-Bus POL Data Sheet
During normal operation the resistors are removed
from the circuit by the switches.
Down” switch is normally closed shorting the resistor
R
open disconnecting the resistor R
An alternative configuration of the margining circuit is
shown in Figure 19.
switches
advantageous in some implementations.
R
from the following equations:
Caution:
Refer to No-Bus
Application Note on
application information on this and other product
features.
Up Switch
Margining
(normally
DOWN
UP
open)
and R
R
Figure 19. Alternative Margining Configuration
R
UP
while the “Margining Up” switch is normally
DOWN
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.
=
DOWN
are
20
20
Down Switch
R
Margining
(normally
=
×
+
UP
open)
for this configuration are determined
20
20
R
R
TM
normally
TRIM
TRIM
×
+
POL Converters. Z-1000 Series
R
R
www.power-one.com
•
TRIM
TRIM
×
0.5V to 5.5V Output
⎛
⎜ ⎜
⎝
In the configuration both
5
×
R
R
×
open
⎛
⎜
⎝
TRIM
DOWN
R
100
TRIM
Δ
V
Δ
Page 15 of 17
UP
−
V
%
.
−
Δ
%
that
The “Margining
Δ
V
REF
TRIM
PGND
V
%
%
⎞
⎟
⎠
, kΩ
⎞
⎟ ⎟
⎠
may
for more
, kΩ
POL
be