HV300 Ver la hoja de datos (PDF) - Supertex Inc

Número de pieza

componentes Descripción

Fabricante

HV300

Hotswap, Inrush Current Limiter Controllers (Negative Supply Rail)

Supertex Inc 

Typical Application Circuit

GND

GND

Long

Pin

Jumper

8

Short

Pin

VDD

R1

487kΩ

3 UV

R2

6.81kΩ

2 OV

R3

9.76kΩ

RAMP

7

PWRGD

1

HV300LG or

HV310LG

VEE

SENSE

GATE

4

5

6

-48V

Long

Pin

C1

10nF

R4

50mΩ

Q1

IRF530

HV300/HV310

Cload

ENABLE

DC/DC

PWM

CONVERTER

+5V

COM

NOTES: 1. Undervoltage Lockout (UV) set to 35V

2. Overvoltage Lockout (OV) set to 65V

3. Remove Jumper if Short Pin is used

Application Information

Under Voltage and Over Voltage Detection

The UV and OV pins are connected to comparators with nominal

1.21V thresholds and 100mV of hysteresis (1.21V ± 50mV).

They are used to detect under voltage and over voltage

conditions at the input to the circuit. Whenever the OV pin rises

above its threshold or the UV pin falls below its threshold the

GATE voltage is immediately pulled low, the PWRGD signal is

deactivated and the external capacitor connected to the RAMP

pin is discharged.

The under voltage and over voltage trip points can be

programmed by means of the three resistor divider formed by

R1, R2 and R3. Since the input currents on the UV and OV pins

are negligible the resistor values may be calculated as follows:

UVoff = VUVH = 1.16 = |VEEUV| * (R2+R3) / (R1+R2+R3)

OVoff = VOVL = 1.26 = |VEEOV| * R3 / (R1+R2+R3)

Where |VEEUV| and |VEEOV| are Under & Over Voltage Set

points.

If we select a divider current of 100µA at a nominal operating

input voltage of 50 Volts then

(R1+R2+R3) = 50V / 100µA = 500kΩ

From the second equation for an Over voltage set point of 65

Volts the value of R3 may be calculated.

OVoff = 1.26 = 65 * R3 / 500kΩ

R3 = (1.26 * 500K) / 65 = 9.69 kΩ

The closest 1% value is 9.76kΩ.

From the first equation for an Under Voltage set point of 35

Volts the value R2 can be calculated.

UVoff = 1.16 = 35 * (R2 + R3) / 500K

R2 = (1.16 * 500K) / 35 – 9.76kΩ = 6.81kΩ.

The closest 1% value is 6.81kΩ.

Then R1 = 500K – (R2 +R3) = 483kΩ

The closest 1% value is 487kΩ.

Undervoltage/Overvoltage Operation

GND

UVOFF

UVON

VIN

OVON

OVOFF

Pass ON

Transistor OFF

Current Limit

The current limit magnitude above which the current will not be

allowed to rise during startup is programmed using a sense

resistor connected from the SENSE pin to VEE pin. For example

to program a current limit of 1A, one would choose a resistor as

follows:

Rsense = 50mV / Isense

Rsense = 50mV / 1A

Rsense = 50mΩ

©2002 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.

6

08/26/02rev.10b

1235 Bordeaux Drive, Sunnyvale, CA 94089

TEL: (408) 744-0100 • FAX: (408) 222-4895

www.supertex.com

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