Datasheet

UBA2037_1 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 01 — 30 October 2008 4 of 14
NXP Semiconductors
UBA2037
Full bridge control IC for HID general lighting
7. Functional description
7.1 Supply voltage
The UBA2037 is powered by a supply voltage applied to pin HV, e.g. the supply voltage of
the full bridge. The IC generates its own low supply voltage for its internal circuitry.
Therefore an additional low voltage supply is not required. A capacitor has to be
connected to pin VDD to obtain a ripple-free internal supply voltage. The circuit can also
be powered by a low voltage supply directly applied to pin VDD. In this case pin HV should
be connected to pin VDD or pin SGND. The maximum current that the internal series
regulator can deliver, is temperature dependent. This is shown in Figure 4.
7.2 Start-up
With an increasing supply voltage the IC enters the start-up state i.e. the upper power
transistors are set in off-state and the lower power transistors are switched on. During the
start-up state the bootstrap capacitors are charged. The start-up state is defined until
V
VDD
=V
startup(VDD)
or V
HV
=V
startup(HV)
. The state of the outputs during the start-up phase
is overruled by the bridge disable function.
7.3 Oscillation state
At the moment the supply voltage on pin VDD exceeds V
startup(VDD)
or the supply voltage
on pin V
HV
exceeds V
startup(HV)
, the output voltage of the full bridge depends on the control
signals on pins CLK, SU, DD and BD. This is listed in Table 3.
As soon as the supply voltage on pin VDD becomes lower than V
UVLO(VDD)
or the supply
voltage on pin V
HV
becomes lower than V
UVLO(HV)
, the IC enters the start-up state again.
n.c. 19 not connected
GLL 17 20 gate driver output for lower left MOSFET
PGND 18 21 power ground
n.c. 19 22 not connected
GLR 20 23 gate driver output for lower right MOSFET
n.c. 21 24 not connected
n.c. 25 not connected
SHR 22 26 source upper right MOSFET
FSR 23 27 floating supply right
GHR 24 28 gate driver upper right MOSFET
Table 2. Pin description
…continued
Symbol Pin
UBA2037T
Pin
UBA2037TS
Description