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UBA3077HN Schematic ( PDF Datasheet ) - NXP Semiconductors

Teilenummer UBA3077HN
Beschreibung Three-channel switched-mode LED driver
Hersteller NXP Semiconductors
Logo NXP Semiconductors Logo 




Gesamt 25 Seiten
UBA3077HN Datasheet, Funktion
UBA3077HN
Three-channel switched-mode LED driver
Rev. 1 — 8 February 2011
Objective data sheet
1. General description
The UBA3077HN is a high efficiency LED driver in an HVQFN40 package for general LED
lighting or backlighting LCD displays.
Operating from a supply of 10 V to 42 V, it can drive up to 3 strings of 20 LEDs each. The
low voltage circuitry is powered by an external 5 V voltage supply.
The chip can operate autonomously or be controlled via a 400 kHz I2C-bus.
The peak current in each string is fixed by an external resistor. Three independent
Pulse-Width Modulated (PWM) signals are available for dimming purposes. These PWM
signals are delivered either directly by the graphic processor (direct control mode) to the
pins PWM1, PWM2 and PWM3, or generated on-board based on data sent via the
I2C-bus interface.
Each LED string is supplied by its own boost converter delivering an output voltage from
VIN up to 75 V. The switching frequency is 500 kHz.
A power saving mode is entered when all PWM signals stay LOW for a period longer than
1 s.
Several protection mechanisms are available: overvoltage, short-circuit and open LED,
overcurrent, UnderVoltage LockOut (UVLO) and overtemperature with an advanced
adaptive protection. An error self-recovery (hiccup) mechanism is available with
programmable delay time via an external capacitor.
2. Features and benefits
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„ Three-channel LED backlight driver
„ Up to 150 mA per channel
„ ±2 % absolute LED current accuracy „ Peak LED current programmable with
and channel-to-channel matching
external resistor
„ External power supply voltage from 10 V „ Three boost converters from VIN up to
to 42 V and 5 V for low voltage circuitry 75 V output voltage
„ Constant 500 kHz frequency peak
„ High efficiency up to 90 %
current mode control
„ Low value output capacitor (2 μF)
„ 14-bit PWM dimming (either defined by
system-generated PWMs, or internally
generated) from 2.0 kHz to 24 kHz (duty
cycle from 0.1 % to 100 %)
„ Accurate internal oscillator
„ All power FETs integrated






UBA3077HN Datasheet, Funktion
NXP Semiconductors
UBA3077HN
Three-channel switched-mode LED driver
Table 3.
Symbol
PWM2
PWM3
SGND
VDD
VIN
IREF
SDA
SCL
SAD0
NC4
NC5
SAD1
FB3
PGND32
LX3
NC6
PGND31
VOUT3
NC7
NC8
PGND22
HICCUP
FB2
NC9
VOUT2
PGND21
Pin description …continued
Pin Type
Reset
state
15 input
-
16 input
-
17 supply
-
18 supply
-
19 supply
-
20 output
-
21 input/output H
22 input
H
23 input
-
24 -
-
25 -
-
26 input
-
27 power
-
28 supply
-
29 power
-
30 -
-
31 supply
-
32 power
-
33 -
-
34 -
-
35 supply
-
36 output
-
37 power
38 -
39 power
40 supply
-
-
-
-
Description
channel 2 PWM input signal
channel 3 PWM input signal
ground of low power circuitry
5 V supply voltage
power supply voltage
connection for an external precision resistor defining
the current in the LED channels
I2C-bus serial data input/output (open-drain)
I2C-bus serial clock input
I2C-bus slave address selection 0
not connected (leave unconnected)
not connected (leave unconnected)
I2C-bus slave address selection 1
channel 3 LED current source output
channel 3 LED current source ground
channel 3 boost converter switch output
not connected (leave unconnected)
channel 3 boost converter switch ground
channel 3 boost converter output voltage
not connected (leave unconnected)
not connected (leave unconnected)
channel 2 LED current source ground
connection for an external capacitor determining the
delay for automatic fault recovery
channel 2 LED current source output
not connected (leave unconnected)
channel 2 boost converter output voltage
channel 2 boost converter switch ground
8. Functional description
8.1 Supply
The UBA3077HN high voltage circuitry requires a nominal supply voltage of 24 V on pin
VIN. The allowed voltage range is 10 V to 42 V.
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The UBA3077HN low voltage circuitry requires a supply voltage of 5 V on pin VDD.
Pins VDD and VIN have a built-in POR function. The POR threshold (falling edge) and
hysteresis is respectively 3.8 V and 200 mV on pins VDD and VIN.
UBA3077HN
Objective data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 8 February 2011
© NXP B.V. 2011. All rights reserved.
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UBA3077HN pdf, datenblatt
NXP Semiconductors
UBA3077HN
Three-channel switched-mode LED driver
All protection circuits are on and continuously monitor for abnormal events.
8.7 Adaptive thermal mode
In Active mode, whenever the die temperature exceeds 120 °C, the chip can
automatically enter Adaptive thermal mode. This mode can be disabled via the I2C-bus
interface.
At each 4 °C step increase in junction temperature above 120 °C, the peak LED current is
reduced by 3 % independently of the duty cycle. This avoids having to deactivate the
backlight suddenly if required, for example if the die overheats. The die temperature can
be read via the I2C-bus.
When the temperature falls below 120 °C, the chip reverts to Active mode.
8.8 Hiccup mode
When a fault is detected, the appropriate protection is triggered; see Section 8.12. The
fault is indicated by pin INT pulled LOW and the protection status register set accordingly.
In response, a constant current source starts charging the external Hiccup capacitor. The
protection is maintained until the voltage on pin HICCUP reaches VDD 0.7 V. This
duration is determined by a fixed 300 μs per 1 nF of the hiccup capacitor value at a VDD of
5 V. A fixed recovery time of 200 μs is added after all faults have disappeared, for
re-calibration in case an OverTemperature Proctection (OTP) or OCP event has occurred.
If the error is still present after the hiccup period, the hiccup restarts. If the error is
removed, the INT line is cleared and the chip reverts to normal operation. The protection
status register content is not automatically cleared.
The external controller can force the protection status to be cleared at any time via the
I2C-bus interface. This is done by writing FFh into the protection status register at address
03h.
www.DataSheet4U.com
UBA3077HN
Objective data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 8 February 2011
© NXP B.V. 2011. All rights reserved.
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