PRODUCT DATASHEET
AAT3151B
TM
ChargePump
High Efficiency 1X/1.5X Charge Pump For White LED Applications
held high for time TLAT. Address or data is differentiated
by the number of EN/SET rising edges. Since the data
20mA Max1
IOUT (mA)
30mA Max 15mA Max
Data
IOUT (mA)
IOUT (mA)
registers are 4 bits each, the differentiating number of
pulses is 24 or 16, so that Address 1 is signified by 17
rising edges, Address 2 by 18 rising edges, and so forth.
Data is set to any number of rising edges between 1 and
including 16. A typical write protocol is a burst of EN/
SET rising edges, signifying a particular address, fol-
lowed by a pause with EN/SET held high for the TLAT
timeout period, a burst of rising edges signifying data,
and a TLAT timeout for the data registers. Once an
address is set, then multiple writes to the corresponding
data register are allowed.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
20.0
17.8
15.9
14.3
12.7
11.1
10.2
8.9
7.9
7.0
6.3
5.7
30.0
26.7
23.8
21.4
19.0
16.7
15.2
13.3
11.9
10.5
9.5
15.0
13.3
11.9
10.7
9.5
8.3
7.6
6.7
6.0
5.2
4.8
4.3
3.8
3.3
3.1
0.0
8.6
7.6
6.7
6.2
When EN/SET is held low for an amount of time greater
than TOFF, the AAT3151B enters shutdown mode and
draws less than 1μA from the supply. Address 1 is the
default address on the first rising edge after the
AAT3151B has been disabled. Whenever shutdown mode
is entered, all registers are reset to 1.
5.1
4.4
4.1
0.0
0.0
Table 1: Constant Current Programming
Levels (mA)2.
AS2Cwire Addressing
AS2Cwire Serial Interface
A number of addresses are available to control all of the
part’s functionality. Use Address 1 to program all four
LED channels to any one of 16 possible settings that
depend on the Max Current scale setting. Use Address 4
to program the Max Current register, which sets the Max
Current scale. Address 5 programs the Low Current
register. The Low Current register controls the highly
efficient Low Current mode.
The AS2Cwire single wire interface is used to set the pos-
sible combinations of current levels and LED channel
states.
AS2Cwire relies on the number of rising edges of the EN/
SET pin to address and load the registers. AS2Cwire
latches data or address after the EN/SET pin has been
AS2Cwire Serial Interface Timing
Address
Data
THI
TLAT
TLO
TLAT
EN/SET
1
2
17
1
18
1
2 . . .
n <= 16
2
Address
1
n
Data Reg 1
1. The device defaults to the 20mA Max scale. Use the Max Current Register to change the Max Scale.
2. There is an additional Low Current mode with currents down to 50μA. See the Low Current Register Settings section.
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3151B.2008.02.1.1
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