Philips Semiconductors
Product specification
HF full bridge driver IC
FEATURES
•
Full bridge driver circuit
•
Integrated bootstrap diodes
•
Integrated high voltage level shift function
•
High voltage input for the internal supply voltage
•
550 V maximum voltage
•
Bridge disable function
•
Input for start-up delay
•
Adjustable oscillator frequency
•
Predefined bridge position during start-up.
APPLICATIONS
•
The UBA2033 can drive (via the MOSFETs) any kind of
load in a full bridge configuration
•
The circuit is especially designed as a commutator for
High Intensity Discharge (HID) lamps.
ORDERING INFORMATION
TYPE
NUMBER
UBA2033TS
PACKAGE
NAME
SSOP28
DESCRIPTION
plastic shrink small outline package; 28 leads; body width 5.3 mm
GENERAL DESCRIPTION
UBA2033
The UBA2033 is a high voltage monolithic integrated
circuit made in the EZ-HV SOI process. The circuit is
designed for driving the MOSFETs in a full bridge
configuration. In addition, it features a disable function, an
internal adjustable oscillator and an external drive function
with a low-voltage level shifter for driving the bridge.
To guarantee an accurate 50% duty factor, the oscillator
signal can be passed through a divider before being fed to
the output driver.
VERSION
SOT341-1
2002 Oct 08
2
Philips Semiconductors
Product specification
HF full bridge driver IC
FUNCTIONAL DESCRIPTION
Supply voltage
The UBA2033 is powered by a supply voltage applied to
pin HV, for instance the supply voltage of the full bridge.
The IC generates its own low supply voltage for the
internal circuitry. Therefore an additional low voltage
supply is not required. A capacitor has to be connected to
pin V
DD
to obtain a ripple-free internal supply voltage.
The circuit can also be powered by a low voltage supply
directly applied to pin V
DD
. In this case pin HV should be
connected to pin V
DD
or SGND.
Start-up
With an increasing supply voltage the IC enters the
start-up state; the higher power transistors are kept off and
the lower power transistors are switched on. During the
start-up state the bootstrap capacitors are charged and the
bridge output current is zero. The start-up state is defined
until V
DD
= V
DD(UVLO)
, where UVLO stands for Under
Voltage Lock-out. The state of the outputs during the
start-up phase is overruled by the bridge disable function.
Release of the power drive
At the moment the supply voltage on pin V
DD
or HV
exceeds the level of release power drive, the output
voltage of the bridge depends on the control signal on
pin EXTDR (see Table 1). The bridge position after
start-up, disable, or delayed start-up (via pin SU) depends
on the status of the pins DD and EXTDR. If pin DD = LOW
(divider enabled) the bridge will start in the pre-defined
position: pin GLR and pin GHL = HIGH and pin GLL and
pin GHR = LOW. If pin DD = HIGH (divider disabled) the
bridge position will depend on the status of pin EXTDR.
If the supply voltage on pin V
DD
or HV decreases and
drops below the reset level of power drive the IC enters the
start-up state again.
Oscillation
At the point where the supply voltage on pin HV crosses
the level of release power drive, the bridge begins
commutating between the following two defined states:
•
Higher left and lower right MOSFETs on,
higher right and lower left MOSFETs off
•
Higher left and lower right MOSFETs off,
higher right and lower left MOSFETs on.
The oscillation can take place in three different modes:
•
Internal oscillator mode.
UBA2033
In this mode the bridge commutating frequency is
determined by the values of an external resistor (R
osc
)
and capacitor (C
osc
). In this mode pin EXTDR must be
connected to pin
+LVS.
To realize an accurate 50% duty
factor, the internal divider should be used. The internal
divider is enabled by connecting pin DD to SGND. Due
to the presence of the divider the bridge frequency
is half the oscillator frequency. The commutation of the
bridge will take place at the falling edge of the signal on
pin RC. To minimize the current consumption
pins
+LVS, −LVS
and EXTDR can be connected
together to either pin SGND or V
DD
. In this way the
current source in the logic voltage supply circuit is shut
off.
•
External oscillator mode without the internal divider.
In the external oscillator mode the external source is
connected to pin EXTDR and pin RC is short-circuited to
pin SGND to disable the internal oscillator. If the internal
divider is disabled (pin DD = V
DD
) the duty factor of the
bridge output signal is determined by the external
oscillator signal and the bridge frequency equals the
external oscillator frequency.
•
External oscillator mode with the internal divider.
The external oscillator mode can also be used with the
internal divider function enabled (pin RC and
pin DD = SGND). Due to the presence of the divider the
bridge frequency is half the external oscillator
frequency. The commutation of the bridge is triggered
by the falling edge of the EXTDR signal with respect to
V
−LVS
.
The design equation for the bridge oscillator frequency is:
1
f
bridge
=
--------------------------------------------------
(
k
osc
×
R
osc
×
C
osc
)
Non-overlap time
The non-overlap time is the time between turning off the
conducting pair of MOSFETs and turning on the next pair.
The non-overlap time is internally fixed to a very small
value, which allows an HID system to operate with a very
small phase difference between load current and full
bridge voltage (pins SHL and SHR). Especially when
igniting an HID lamp via a LC resonance circuit, a small
‘dead time’ is essential. The high maximum operating
frequency, together with a small ‘dead time’, also gives the
opportunity to ignite the HID lamp at the third harmonic of
the full bridge voltage, thereby reducing costs in the
magnetic power components.
2002 Oct 08
5
Embedded System
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