UBA3070T/N1,118 NXP Semiconductors, UBA3070T/N1,118 Datasheet - Page 5

• Manufacturer Part Number: UBA3070T/N1,118
• Description: IC LED DVR WHITE BCKLGT 8-SOIC
• Manufacturer: NXP Semiconductors
• Type: Backlight, White LEDr

Specifications of UBA3070T/N1,118

• Package / Case: 8-SOIC (3.9mm Width)
• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 145kHz ~ 205kHz
• Voltage - Supply: 9.3 V ~ 10.6 V
• Voltage - Output: 12V
• Mounting Type: Surface Mount
• Internal Switch(s): Yes
• Number Of Segments: 2
• Low Level Output Current: 0.56 uA (Typ)
• High Level Output Current: - 0.135 uA (Typ)
• Operating Supply Voltage: 9.3 V to 10.6 V
• Maximum Supply Current: 1500 uA
• Maximum Power Dissipation: 500 mW
• Maximum Operating Temperature: + 145 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature (min): -40C
• Operating Temperature Classification: Automotive
• Package Type: SO
• Pin Count: 8
• Mounting: Surface Mount
• Power Dissipation: 500mW
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Operating Temperature: -
• Current - Output / Channel: -
• Efficiency: -
• Lead Free Status / Rohs Status: Compliant
• Other names: 568-4924-1

NXP Semiconductors
UBA3070
Product data sheet
7.3 Masking and valley switching
7.4 Conversion frequency
7.5 Minimum on-time
7.6 OverCurrent Protection (OCP)
7.7 OverTemperature Protection (OTP)
7.8 Driver
The MASK pin ensures that switch-on of the converter is at a valley during ringing and not
at a peak during freewheeling of the inductor. If the voltage level at the MASK pin is above
100 mV, then switch-on of the switching FET is prevented. If the voltage level is below
100 mV, then switch-on prevention of the FET is released and at the moment of valley
detection the FET is turned on. The signal for the MASK pin can be derived from the
signal at the switch node as shown in
must be lower than the typical stop current of 60 μA.
If the MASK pin is open circuit or not connected, a fault condition is assumed and the
converter stops operating immediately. Operation restarts as soon as the fault condition is
removed.
The maximum conversion frequency of the UBA3070 is limited to 175 kHz. However, due
to production spread, the maximum conversion frequency of an individual UBA3070
sample can be as low as 145 kHz. Therefore, an inductance value must be selected so
that the applications conversion frequency always remains below 145 kHz after taking into
account variations due to the supply voltage, LED string voltage and component spread.
There is no limitation for the minimum conversion frequency.
The LEB time, typically 370 ns is a fixed delay that determines the minimum on-time of the
controller. The LEB time prevents the MOSFET switch from switching off unintentionally
(due to coupling to the sense node) directly after the start of a conversion cycle.
As the converter acts as a current source it is self-protected from overcurrent by an extra
level of protection, i.e. a second trip level of typically 0.88 V applied to the short-winding/
sense node as shown in
convertor against short-circuits in external components e.g. in the diodes, inductors,
capacitors and/or LEDs. If a short-circuit is detected the convertor stops switching.
OTP is provided in the UBA3070 IC and functions as follows. When the junction
temperature exceeds the thermal shutdown temperature of typically 140 °C the converter
stops switching.
The driver circuit to the gate of the power FET has a current sourcing capability of
approximately 135 mA and a current sinking capability of 560 mA. This capability means
the FET operates more efficiently with fast switch-on and switch-off cycles. A low driver
source current has been chosen to limit the ΔV/Δt at switch-on thereby reducing EMI and
voltage spikes across R
All information provided in this document is subject to legal disclaimers.
Rev. 3 — 9 December 2010
sense
Figure
.
1. This second trip level is designed to protect the
Figure
2. The current flowing into the MASK pin
LED backlight driver IC
UBA3070
© NXP B.V. 2010. All rights reserved.
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