HV111
Pin Description
V
PP
HV111
Regulator
M2
PWRGD
V
PP
–
Positive voltage supply input
V
NN
– Negative voltage power supply input
DRAIN
– Internal N-Channel MOSFET drain output
UVLO/ENABLE
– Under Voltage lockout input or Enable
PWRGD
– Active Low Power Good Output
UVLO/
Enable
UVLO
DRAIN
CONTROL
POR Timer
LOGIC
D
Temperature
Sense
V
NN
M1
Restart
TImer
1
2000
M0
S
V
NN
EN UV PP
AB LO
LE /
PW
V
Figure 1
−
Internal Blocks of HV111
Many systems include front end capacitance to provide low
impedance energy and filtering to power systems. These
systems include hot pluggable live-backplane systems, such
as –48V telecom systems and switched systems such as
battery connected backed-up loads.
This filter capacitance, usually implemented as large
electrolytic capacitors, looks like a low impedance
connected directly across the power supply terminals and
causes high inrush currents which could damage
connectors, traces or components (such as the capacitors
themselves). These high currents may also cause localized
glitching of the backplane or EMI that could reset or interrupt
surrounding circuit cards.
The HV111 is a single chip solution that provides bullet-
proof power management control for systems with loads
less than 1.65A. See Thermal Shutdown section for power
dissipation limitation. The HV111 does not require the use of
any external components or programming and eliminates
the need for a sense resistor. Where desired, however,
internal set points may be overridden with external
components – for example an external resistor divider may
be used to set the UVLO/ENABLE threshold.
Turn on Protection
(UVLO/POR for Debounce + PWM limit)
PWM I
limit
DR
Functional Description
RG
D
AI
N
I
DS
200mA/div
V
PP
-V
NN
POR
High Voltage Regulator
The HV111 includes a high voltage regulator capable of
operation with V
PP
-V
NN
=8.0V to 80V. The regulator provides
an internal voltage to operate circuitry and drive the internal
1Ω MOSFET pass element.
Figure 2
−
UVLO & POR + Dead Short Protection
The second subsystem is the UVLO/POR that work together
to debounce. Leave the UVLO input open to use the default
setting of –26V with 2.5V hysteresis. This default setting can
be over driven with an external resistive divider. The
comparator threshold is 1.2V with respect to V
NN
. The HV111
is capable of operation down to 8.0V for automotive
applications to 80V for the most rugged telecom
applications.
The third subsystem, PWM Iimit, is protection for turning on
into a short (or a later dead short). In this case the HV111
helps avoid the dumping of large currents into the load by
pulse width modulating (PWM) the current to limit Inrush
current to <250mA average if V
pp
-V
DRAIN
<~1V.
3
SUPERTEX [ Supertex, Inc ]
