uba20261 NXP Semiconductors, uba20261 Datasheet - Page 6

• Manufacturer Part Number: uba20261
• Description: 600 V And 350 V Power Ic For Step Dimmable Cfls
• Manufacturer: NXP Semiconductors

NXP Semiconductors
UBA20261_UBA20262
Preliminary data sheet
7.1.1 Reset state
7.1.2 Start-up state
7.1.3 Preheat state
7.1 Lamp start-up cycle
The UBA20261/2 are in the reset state when the supply voltage on the V
the V
counters and timers are undefined. The hold state latch is reset and both the high and low
side power transistors are non-conductive.
During power-up, the low voltage supply capacitor on the V
external start-up resistor. The start-up state is entered when the voltage on the V
above the V
on the V
The start-up state is entered by charging the low voltage supply capacitor on the V
through the external start-up resistor. At start-up, the High-Side (HS) transistor is
non-conductive and the Low-Side (LS) transistor is conductive to enable charging of the
bootstrap capacitor. This capacitor supplies the HS driver and Level shifter circuit
connected between the FS and HBO pin. A DC reset circuit is integrated into the HS
driver. This circuit ensures that below the FS pin lockout voltage, the output voltage
V
When the start-up state is entered, the circuit only starts oscillating when the low voltage
supply (V
The circuit enters the preheat state as soon as the capacitor connected to the CP pin is
charged above the V
V
During the start-up state, the voltage on the CF pin is zero and on the CB pin is close to
zero. The voltage on the CP pin rises just above V
shown in
After starting at f
output current circuit. The preheat current sensor circuit controls the current output circuit,
until the momentary value of the voltage across sense resistor R
preheat voltage level (SLS pin). At this level, the current of the preheat current sensor
reaches the charge and discharge balanced state on capacitor C
frequency.
The preheat time consists of eight saw-tooth pulses at the CP pin. The preheat time
begins as soon as the capacitor on the CP pin is charged above V
the preheat time, the current feedback sensor circuit (input CSI pin) is disabled.
To increase noise immunity, an internal filter of 30 ns is included at the SLS pin.
If the level on the V
immediately stopped and the circuit enters the hold state. The hold state delays a new
preheat cycle by a fixed delay time. A fixed voltage drop on the preheat capacitor C
the fixed discharge current on the CP pin are used to set the delay time.
GHS
DD(stop)
DD(rst)
 V
DD
and below the V
HBO
DD
Figure
level. In the reset state, part of the internal supply is turned off and all registers,
pin drops below V
) reaches the V
DD(rst)
is zero.
All information provided in this document is subject to legal disclaimers.
bridge(max)
9.
level. The UBA20261/2 enters the reset state when the supply voltage
DD
th(CP)max
Rev. 1 — 9 September 2011
pin drops below V
DD(clamp)
, the frequency decreases by charging capacitor C
DD(start)
DD(rst)
voltage level. To keep oscillating, V
upper limit.
value. The circuit always starts oscillating at f
.
600 V and 350 V power IC for step dimmable CFLs
DD(stop)
during preheat, the preheat state is
th(CP)max
DD
during the start-up state as
pin is charged through the
UBA20261/2
SLS
DD
CI
th(CP)max
to set the half-bridge
must be above
reaches the fixed
© NXP B.V. 2011. All rights reserved.
DD
value. During
pin is below
CI
using an
bridge(max)
DD
CP
DD
pin is
6 of 32
and
pin
.