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Y5017P 17A DC-DC POL Data Sheet
3.0V to 13.2V Input
0.7V to 3.63V Output
REV. 1.0 APR 16, 2004
www.power-one.com
Page 9 of 16
6.
Feature Description
6.1
Enable
This function allows the converter to be turned on or off
remotely. The Enable pin is internally pulled up to the
input voltage. It is recommended to control the Enable
pin with an open collector transistor. The saturation
voltage of the transistor shall be less than 0.55V at 1mA
to reliably turn the converter OFF.
If the Enable pin is not used, it shall be left floating.
6.2
Internal Supply Voltage (VLDO)
If the input voltage is lower than 5.2V, then the VLDO
pin is required to be connected to an external voltage
source (
≥5.2V). This voltage should not exceed 15V
and be capable of supplying 60mA.
6.3
Undervoltage Lockout
The undervoltage lockout scheme monitors the input
voltage applied to it and does not allow the converter
to start when VIN is less than the UVLO threshold.
When the input voltage is higher than 5.2V, the VLDO
pin is connected to the input voltage and UVLO turn-
on threshold is typically 3.8V. When the input voltage
is below 5.2V, the VLDO pin connected to an external
voltage source. UVLO turn-on threshold is then set
with the 10kOhm resistor connected between the
Enable pin and the ground as shown in Figure 13.
6.4
Output Voltage Trim
The output voltage is preset to 1.3V. The trim feature
allows the user to adjust the output voltage from this
nominal value.
Increase VOUT: Trim range 1.3V < VOUT ≤ 3.63V. An
external resistor (RTU) is placed between the Trim pin
and the –Vs (negative voltage sense) pin.
RTU = 137.5/(VOUT-1.3), k
Decrease VOUT: Trim range 0.7V ≤ VOUT < 1.3V.
An external resistor (RTD) is placed between Trim pin
and VREF pin.
RTD = 110(VREF – 1.25) / (1.3 – VOUT) k
Note that VOUT cannot exceed 0.7VIN.
An internal 5V (+/-2.5%) reference voltage is available
from VREF (pin 19).
Alternatively, an external
reference voltage can be used for better accuracy
(typically 1%). The external reference voltage should
be in the range from 1.26V to 5.5V and capable of
supplying 1mA.
Table 1. Sample Trim Resistance Values
VOUT (V)
RTD (k
)
RTU (k
)
0.7
686.36, (VREF = 5V)
1.0
1370, (VREF = 5V)
1.25
8088, (VREF = 5V)
1.3
------ None – factory default -----
1.5
690.95
2.5
114.68
3.3
68.78
6.5
Output Current Limit
When the output load exceeds the current limit
threshold, the converter will enter a low power hiccup
mode. Once the overcurrent is removed, the output
voltage will recover automatically.
6.6
Output Current Limit Adjustment
The OCP adjustment function allows greater flexibility
to set the output current limit inception point (ILIM),
from default of 22A to a minimum of 1
3.6A using an
external resistor and a capacitor. To adjust the ILIM,
place the resistor ROCP between OCPA and OCPB
pins, and the capacitor COCP between OCPA and Vout
pins. Do not short OCPA directly to OCPB.
To calculate ROCP and COCP, use the equations below:
ROCP = 15(ILIM -12.6) / (28 - ILIM ), k
COCP = 411.3/ROCP - 8, nF,
where ROCP is on k
Table 2. Sample Standard Values for ROCP and COCP
ILIM
ROCP
COCP
~22A
Open
None
~20A
14k
22nF
~17A
6.04k
56nF
~13.6A
1k
390nF
6.7
Remote Voltage Sense
This feature provides improved load regulation by
compensating for the voltage drop between the output
of the converter and the load.