HV310 Supertex Inc, HV310 Datasheet - Page 6

• Manufacturer Part Number: HV310
• Description: Hotswap/ Inrush Current Limiter Controllers
• Manufacturer: Supertex Inc

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:
Where
points.
If we select a divider current of 100µA at a nominal operating
input voltage of 50 Volts then
From the second equation for an Over voltage set point of 65
Volts the value of R3 may be calculated.
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.
©2002 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
Typical Application Circuit
(R1+R2+R3) = 50V / 100µA = 500kΩ
OV
UV
off
OV
R3 = (1.26 * 500K) / 65 = 9.69 kΩ
off
|
V
= V
= V
EEUV
off
= 1.26 = 65 * R3 / 500kΩ
UVH
OVL
GND
-48V
|
and
GND
= 1.26 =
= 1.16 =
|
6.81kΩ
9.76kΩ
V
487kΩ
Long
EEOV
Short
Pin
Long
Pin
Pin
R1
R2
R3
|
|
V
V
|
EEUV
EEOV
Jumper
are Under & Over Voltage Set
|
|
3
2
* (R2+R3) / (R1+R2+R3)
* R3 / (R1+R2+R3)
UV
OV
RAMP
V
7
DD
8
C1
10nF
4
V
HV300LG or
HV310LG
EE
50mΩ
R4
SENSE
5
PWRGD
6
6
GATE
IRF530
Transistor
Q1
Then R1 = 500K – (R2 +R3) = 483kΩ
The closest 1% value is 487kΩ.
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 V
to program a current limit of 1A, one would choose a resistor as
follows:
Pass
1
V
Rsense = 50mV / Isense
Rsense = 50mV / 1A
Rsense = 50mΩ
IN
OV
UV
OV
UV
GND
Undervoltage/Overvoltage Operation
OFF
OFF
UV
R2 = (1.16 * 500K) / 35 – 9.76kΩ = 6.81kΩ.
The closest 1% value is 6.81kΩ.
OFF
ON
ON
ON
off
NOTES: 1. Undervoltage Lockout (UV) set to 35V
Cload
= 1.16 = 35 * (R2 + R3) / 500K
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TEL: [phone] • FAX: [phone]
2. Overvoltage Lockout (OV) set to 65V
3. Remove Jumper if Short Pin is used
ENABLE
CONVERTER
DC/DC
PWM
+5V
COM
EE
www.supertex.com
pin. For example
HV300/HV310
08/26/02rev.10b