Pisces Series, Page 3

Part No. 99-002 Rev. 4.0–093003

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Undervoltage Lockout

30

32

36

34

40

38

Input Voltage (V)

Voltage

Rising

Voltage

Falling

Overvoltage Lockout

75

76

78

77

80

79

Input Voltage (V)

Voltage

Rising

Voltage

Falling

•Patented single-stage power conversion architecture,

control, and magnetic design allow unprecedented power

density and efficiency in an isolated power supply.

• An advanced microcontroller reduces parts count while

adding features, performance, and flexibility in the design.

• Low common-mode noise as a result of lower capacitance

in the transformer compared to planar magnetics and

metal baseplate designs.

• Higher reliability than planar transformer designs that can

suffer from via fatigue from thermal cycling, and metal

baseplate designs with board to board interconnects that

are subject to mechanical stress on electrical connections.

Protection and Control

Valid Input Voltage Range:

The converter measures the input voltage and will not

allow operation outside of the input voltage

specification. As shown by the graphs, hysteresis is

added to both the high and low voltage to prevent the

converter from turning on and off repeatedly when the

voltage is held near either voltage extreme. At low line

this assures the maximum input current is not exceeded;

at high line this assures the semiconductor devices in

the converter are not damaged by excessive voltage

stress.

ON/OFF Logic Option:

The ON/OFF control logic can be either Negative

(standard) or Positive to enable the converter. For

Negative logic, the ON/OFF pin is brought below 1.0 V

with respect to the –INPUT pin to enable the converter.

The pull down must be able to sink 100

µA. For

Positive logic, the ON/OFF pin is brought to greater

than 4.0V with respect to the –INPUT pin and be

limited to less than 10V. To request the Positive logic

version, add the suffix (P) to the standard part number.

The ON/OFF pin has a built-in pull up resistor of

approximately 100k

Ω to +5V.

Application Notes