HV9606X Supertex Inc, HV9606X Datasheet - Page 5

• Manufacturer Part Number: HV9606X
• Description: HV9606 Current-Mode PWM Controller with Supervisor
• Manufacturer: Supertex Inc

Functional Block Diagram
Functional Description
The HV9606 is composed of several functional blocks.
operation of each of these blocks is described in the following
sections.
Programmable Start/Stop Control Circuit
(Programmable Under Voltage Lockout and Hysteresis)
The START/STOP control circuit is a novel version of a
programmable
hysteresis circuit. It is novel, because it requires zero power (other
than the current in the resistor divider) and keeps the startup
regulator shut down until the START threshold voltage is
exceeded, allowing the HV9606 to achieve its low input leakage
current of <6 A.
One can think of the circuit as a transparent latch, such that its
output is high when the START pin is above its threshold voltage
and is latched when the STOP pin is at a voltage greater than the
START pin voltage. It is unlatched when the STOP pin voltage
falls below its threshold voltage and the START pin is below its
threshold voltage.
START
STOP
Vin
Supertex, Inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 TEL: [phone] FAX: [phone] www.supertex.com
RT
Oscillator
under
SYNC
Programable
Start/Stop
Circuit
STATUS SENSE
voltage
CLK
D
Supervisor
Circuit
CLR
___
Vdd
Q
_
Q
Regulator
Enable
lockout
Oscillator
Enable
Soft
Start
Enable
SS
Regulator
Start-Up
with
Reference
Generator
Bandgap
Circuit
VREF
Soft
Start
programmable
NI
The
FB
Vdd
UVLO
A
COMP
C
5
These operating conditions are met by using a voltage divider
consisting of three resistors (see typical application circuit). The
voltage drop on the resistor connected to ground controls the
START voltage and the additional voltage drop on the middle
resistor sets the hysteresis and controls the STOP voltage. Setting
the value of the middle resistor to zero results in zero hysteresis.
Provided the START and STOP pin input currents are negligible in
comparison to the chosen resistor divider current, the resistor
values may be calculated using the following equations:
R3 = (V
R2 = [(V
R1 = (V
Where:
V
V
V
V
I
Resistor
R
START
STOP
IN-Start
IN-Stop
R
C
is the STOP pin threshold voltage (nominal 7V)
is the resistor divider current (>1 A)
is the START pin threshold voltage (nominal 7V)
is the input voltage at which shutdown is desired
is the input voltage at which starting is desired
START
IN-Operating
VX2
UVLO
STOP
/ V
/ V
C
C
IN-Stop
IN-Start
/ I
Resistor
Current
Limit
) x (V
) x (V
R
R
S
) - R2 - R3
IN-Stop
IN-Stop
Q
/ I
/ I
85 nS Delay
Resistor
Resistor
)] – R3
)
Voltage
Doubler
4/15/2002-R.L2
HV9606
PGND
SGND
GATE
VX2
Vdd
CA
CB
CS