Features Descriptions CON | Delta Electronics Series DNS manual

FEATURES DESCRIPTIONS (CON.)

Over-Temperature Protection

The over-temperature protection consists of circuitry that provides protection from thermal damage. If the temperature exceeds the over-temperature threshold the module will shut down. The module will try to restart after shutdown. If the over-temperature condition still exists during restart, the module will shut down again. This restart trial will continue until the temperature is within specification.

Remote Sense

The DNS provide Vo remote sensing to achieve proper regulation at the load points and reduce effects of distribution losses on output line. In the event of an open remote sense line, the module shall maintain local sense regulation through an internal resistor. The module shall correct for a total of 0.5V of loss. The remote sense line impedance shall be < 10Ω.

Distribution Losses	Distribution Losses
Vin	Vo

Sense

	GND
Distribution	Distribution
	L

Figure 36: Effective circuit configuration for remote sense operation

Output Voltage Programming

The output voltage of the DNS can be programmed to any voltage between 0.75Vdc and 3.3Vdc by connecting one resistor (shown as Rtrim in Figure 37) between the TRIM and GND pins of the module. Without this external resistor, the output voltage of the module is 0.7525 Vdc. To calculate the value of the resistor Rtrim for a particular output voltage Vo, please use the following equation:

⎡	21070	⎤
Rtrim = ⎢		− 5110⎥Ω

⎣Vo − 0.7525		⎦

For example, to program the output voltage of the DNS module to 1.8Vdc, Rtrim is calculated as follows:

⎡	21070	⎤
Rtrim = ⎢		− 5110⎥Ω = 15KΩ
	− 0.7525
⎣1.8		⎦

DNS can also be programmed by apply a voltage between the TRIM and GND pins (Figure 38). The following equation can be used to determine the value of Vtrim needed for a desired output voltage Vo:

DS_DNS04SIP06A_07172008

Vtrim = 0.7 − 0.1698 ⋅ (Vo − 0.7525)

For example, to program the output voltage of a DNS module to 3.3 Vdc, Vtrim is calculated as follows

Vtrim = 0.7 − 0.1698 ⋅ (3.3 − 0.7525) = 0.267V

RLoad

TRIM

Rtrim

GND

Figure 37: Circuit configuration for programming output voltage using an external resistor

Vtrim RLoad

	TRIM
GND	+
	+
		_

Figure 38: Circuit Configuration for programming output voltage using external voltage source

Table 1 provides Rtrim values required for some common output voltages, while Table 2 provides value of external voltage source, Vtrim, for the same common output voltages. By using a 1% tolerance trim resistor, set point tolerance of ±2% can be achieved as specified in the electrical specification.

Table 1

Vo(V)	Rtrim(KΩ)
0.7525	Open
1.2	41.97
1.5	23.08
1.8	15.00
2.5	6.95
3.3	3.16

Table 2

Vo(V)	Vtrim(V)
0.7525	Open
1.2	0.624
1.5	0.573
1.8	0.522
2.5	0.403
3.3	0.267