HV311LG Ver la hoja de datos (PDF) - Supertex Inc

Número de pieza

componentes Descripción

Fabricante

HV311LG

Hot Swap Controller (Negative Supply Rail)

Supertex Inc 

Design Information, cont’d.

Undervoltage/Overvoltage Operation

GND

UVOFF

UVON

VIN

OVON

OVOFF

Pass ON

Transistor OFF

From the calculated resistor values the OV and UV start up

threshold voltages can be calculated as follows:

UVON

= VUVH

= 1.26 =

VEEUV(on)

×

R2 + R3

R1 + R2 + R3

OVON

= VOVL

= 1.16 =

VEEOV(on)

×

R3

R1 + R2 + R3

Where |VEEUV(on)| and |VEEOV(on)| are Under & Over Voltage Start

Up Threshold points relative to VEE.

Then

VEEUV(on)

= 1.26 ×

R1 + R2 + R3

R2 + R3

VEEUV(on)

= 1.26 ×

487kΩ + 6.81kΩ + 9.76kΩ

6.81kΩ + 9.76kΩ

= 38.29V

And

VEEOV(on)

= 1.16 ×

R1 + R2 + R3

R3

VEEOV(on)

= 1.16 ×

487kΩ + 6.81kΩ + 9.76kΩ

9.76kΩ

= 59.85V

Therefore, the circuit will start when the input supply voltage is

in the range of 38.29V to 59.85V.

Programming Inrush and ICB

Method 1: Inrush independent of ICB

VSENSE

10V

10A

7.5A

2.5A

5k

7.5A

C2

–+

0A

GATE

+K–

RAMP

0A

Vgs +

10n

–

Cgd

Cgs

dv on Cramp constant

df during limiting so no

current flowing into cap

inrush

Vin

+

Cload=100F

–

gm(Vgs-Vt)

Rsense=12.5mW

(DRAIN)

Cdb

VSENSE

10V

10A

VSENSE

10A

Isink

5k

RAMP

terminal

10n=Cramp

HV301/HV311

C2

0.75nF

1 : 2 mirror

Internal Circuitry

48V

Cload

GATE

Termial

Rsense

Vsense

1. Choose circuit breaker trip point eg. 8A as follows

Rsense = 100mV = 100mV = 12.5mΩ

ICB

8

2. Choose inrush level, for example Inrush = 1A

3. Calculate Isink = Inrush*Rsense = 1A ×12.5mΩ = 2.5µA

5kΩ

5kΩ

4. Calculate C2 discharge limit

= 10µA -Isink = 7.5µA (typical) = iC2

4a. Adjust for Auto -retry disable, if used →

≅ Vtmax e.g. 4V = 1.6µA

R disable

2.5MΩ

⇒ e.g. iC2 = 10µA -Isink -1.6µA

In this example we assume Auto-retry is enabled so

ignore 1.6µA, ∴ iC2 = 10µA -Isink = 7.5µA

5. Note: i = C dv

dt

iC2

=

C2

×

dv

dt

Inrush

=

Cload

×

dv

dt

Note VIN is fixed and VRAMP is constant during limiting

⇒

dv

dt

across Cload =

dv

dt

across C2

(as they share a

common node and their other terminals are fixed during inrush)

iC2 = Inrush ⇒ Inrush = iC2 × Cload

C2 Cload

C2

by conservation of charge on RAMP Node iC2 = 7.5µA

Inrush =

7.5µA × Cload

C2

⇒ C2

=

7.5µA × Cload

Inrush

= 7.5µA ×100nF = 750pF = 0.75nF

1A

Note that RAMP is protected by AC divider and Gate

is clamped internally.

A092605

6

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