AAT2869 Advanced Analogic Technologies, Inc., AAT2869 Datasheet - Page 14

• Manufacturer Part Number: AAT2869
• Description: Fade-in/fade-out 4 Channel Backlight Driver With Dual Ldos
• Manufacturer: Advanced Analogic Technologies, Inc.

AS
The AAT2869 is dynamically programmable using the
AS
edges detected at the EN/SET pin to address and load
the data registers. The timing diagram in Figure 1 shows
the typical transmission protocol.
The AAT2869 latches address or data after the EN/SET
input has been held high for time t
AS
the number of EN/SET rising edges. An address has from
17 to 22 EN/SET rising edges; data has from 1 to 16 EN/
SET rising edges. A typical AS
tocol is a burst of EN/SET rising edges identifying a par-
ticular address, followed by a pause with EN/SET held
high for the t
edges signifying data, and another t
data has been sent. Once an address is set, multiple
writes to that address are allowed since the address is not
reset after each write. Address edges are needed when
changing the address, or writing to an address other than
the default after shutdown. Address 0 is the default
address after shutdown. If the part is enabled with only
14
SystemPower
2
2
LDOA = 1.8V, LDOB = 2.8V [default]
Cwire interface. Address and data are differentiated by
Cwire single-wire interface. AS
2
Cwire EN/SET Interface
LDOA = 3.0V, LDOB = 2.8V
LDOA = 3.0V, LDOB = 1.8V
LDOA = 3.0V, LDOB = 1.5V
LDOA = 3.0V, LDOB = 1.2V
LDOA = 2.8V, LDOB = 2.8V
LDOA = 2.8V, LDOB = 1.8V
LDOA = 2.8V, LDOB = 1.5V
LDOA = 2.8V, LDOB = 1.2V
LDOA = 1.8V, LDOB = 1.8V
LDOA = 1.8V, LDOB = 1.5V
LDOA = 1.8V, LDOB = 1.2V
LDOA = 1.5V, LDOB = 2.8V
LDOA = 1.5V, LDOB = 1.8V
LDOA = 1.5V, LDOB = 1.5V
LDOA = 1.5V, LDOB = 1.2V
Description
LAT
Table 6: AS
timeout period, then a burst of rising
TM
2
Cwire Register Address 5 LDOA and LDOB Output Voltage Settings.
2
Cwire interface write pro-
LAT
Fade-In/Fade-Out 4 Channel Backlight Driver with Dual LDOs
2
Cwire records rising
LAT
(500μs) through the
timeout after the
LDO[3]
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
w w w . a n a l o g i c t e c h . c o m
LDO[2]
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
one rising edge after shutdown, then Address 0 will be
programmed and LED backlight channels BL1-BL4 will be
enabled to the default setting of 20mA each.
When EN/SET is held low for a time longer than t
(500μs), the AAT2869 enters shutdown mode with the
charge pump and both LDOs all turning off and draws
less than 1μA of current from IN. At shutdown, the data
and address registers are reset to 0.
Short Circuit and
Over-Temperature Protection
The AAT2869 integrates short circuit protection to limit
the input current in case of the charge pump output or
the two LDO outputs are shorted to ground by fault. The
backlight and the two LDOs will recover to normal oper-
ation once the fault is removed.
The AAT2869 also includes over-temperature protection
circuitry. When the junction temperature is too high, the
over-temperature protection circuitry is active and the IC
enters standby mode, turning off the LED current and
LDO outputs. When the fault is removed, the LED back-
lighting and the LDO outputs all recover.
LDO[1]
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Data
LDO[0]
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
PRODUCT DATASHEET
EN/SET Rising Edges
AAT2869
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
2869.2010.01.1.0
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