ISL6720A

FN6487 Rev.1.00

Page 7 of 11

August 23, 2007

Pin Descriptions

VPWR - VPWR is the primary power connection for the IC.

The under voltage lockout (UVLO) feature of VPWR

enables/disables all outputs even if VIO is externally biased.

To optimize noise immunity, bypass VPWR to GND with a

ceramic capacitor as close to the VPWR and GND pins as

possible.

VCONT - A 25mA continuous output that derives its source

voltage from either VIO (when enabled and sufficient) or

VPWR (when VIO is not available). VCONT sequences on

before VIO and VSW by approximately 250

s.

The over-temperature protection feature protects VCONT at

a higher temperature than VIO and VSW. This ensures VIO

and VSW shutdown at a lower temperature and allows

VCONT to remain on.

VCOMP - A 1000pF compensating capacitor is placed

between VCOMP and VCONT to stabilize the control loop.

This value may vary depending on the output load and

capacitance applied between VCONT and GND.

VIO - This is the unswitched low voltage output supply. It

may be used as is, or may be back-biased by an auxiliary

power source such as a transformer winding. VIO should be

bypassed to GND with a 0.1

F capacitor. Although a

minimum capacitance is not required, it does provide the

source voltage bypass for VSW and VCONT when VIO is

capable of supporting those outputs. Smaller values of

capacitance will result in larger disturbances during load

transients. Its output is adjustable from 0V to 20.0V using a

reference on VADJ, such as a zener diode and bias resistor.

VIO may be soft-started with a capacitance to ground from

VADJ.

VADJ - The feedback adjustment pin for VIO. An external

reference on VADJ sets the voltage on VIO. The reference

may be a resistor/zener diode combination from VPWR.

VADJ has a discharge device that activates momentarily

during power-up and power-down sequences to allow VIO to

be soft started.

GND - Signal and power ground connections for this device.

Typical Performance Curves

FIGURE 3. VCONT REGULATION vs TEMPERATURE

FIGURE 4. VSW REGULATION vs TEMPERATURE

0

10

20

30

40

50

60

70

80

90

100

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

VIO LOAD (mA)

VADJ = 15V

VADJ = 10V

VADJ = 20V

0

10

20

30

40

50

60

70

80

90

100

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

VIO LOAD (mA)

VPWR = 48V

VPWR = 20V

VPWR = 80V

-40

-25

-10

5

20

35

50

65

80

95

110

0.997

0.998

0.999

1.000

1.001

TEMPERATURE (°C)

-40

-25

-10

5

20

35

50

65

80

95

110

0.998

0.999

1.000

1.001

1.002

TEMPERATURE (°C)

VSW = 5.0V

VSW = 3.3V

VSW = 20V

VSW = 12V