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AS3687/87XM
Flexible Lighting Management Unit
General Description
The AS3687/87XM is a highly-integrated CMOS lighting
management unit for mobile telephones, and other 1-cell Li+
or 3-cell NiMH powered devices.
The AS3687/87XM incorporates one step up DC/DC converter
for white backlight LEDs, one low noise charge pump for
indicator- or RGB- LEDs, LED test circuit (production test of the
soldered LEDs at the customer site), one analog-to-digital
converter, seven current sinks, a two wire serial interface, audio
light and control logic all onto a single device. Output voltages
and output currents are fully programmable. The AS3687XM
has an audio input to control one or two RGB LEDs.
The AS3687/87XM is a successor to the ams AS3689 and
therefore software compatible to the AS3689 (software written
for the AS3689 can be easily reused for the AS3687/87XM).
Ordering Information and Content Guide appear at end of
datasheet.
Key Benefits & Features
The benefits and features of AS3687/87XM, Flexible Lighting
Management Unit are listed below:
Figure 1:
Added Value Of Using AS3687/87XM
Benefits
• Superior battery life time due to high
efficient DC/DC step up converter and
low noise charge pump
ams Datasheet
[v3-05] 2015-Oct-23
Features
• High-efficiency step up DC/DC converter
• Up to 25V/50mA for white LEDs
• Programmable output voltage with external resistors
and serial interface
• Overvoltage protection
• High-efficiency low noise charge pump
• 1:1, 1:1.5, and 1:2 Mode
• Automatic up switching (can be disabled and 1:2 mode
can be blocked)
• Output current up to 150mA
• Efficiency up to 95%
• Only 4 external capacitors required: 2×500nF flying
capacitors, 2×1μF input/output capacitors
• Supports LCD white backlight or RGB LEDs
Page 1
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AS3687/87XM − General Description
Benefits
Features
• Maximum number of LEDs driven by
one lighting management unit
• Seven current sinks
• All seven current sinks fully programmable (8-bit) from
0.15mA to 38.5mA (CURR1, CURR2, CURR6, CURR30,
CURR31, CURR32, CURR33)
• Three current sinks are high voltage capable
(CURR1, CURR2, CURR6)
• Selectively enable/disable current sinks
• Full flexibility in light pattern generation
due to high integration
• Internal PWM generation
• 8 Bit resolution
• Autonomous logarithmic up/down dimming
• LED pattern generator
• Autonomous driving for fun RGB LEDs
• Support indicator LEDs
• On chip system monitor
• 10-bit successive approximation ADC
• 27μs conversion time
• Selectable inputs: all current sources,
VBAT, CP_OUT, DCDC_FB
• Internal temp. measurement
• Audio synchronized RGB LED lighting
• Audio can be used to drive RGB LED (AS3687XM only)
• RGB color and brightness is dependent on audio input
amplitude
• Can drive one or two RGB LEDs
• Wide battery supply range
• Supply voltage 3.0 to 5.5V
• On chip safety features
• Overcurrent, thermal protection and automatic OPEN and
SHORT LED test
• Smallest PCB footprint and lowest BOM
• Small package
• WL-CSP 4×5 balls 0.5mm pitch
Applications
The AS3687/87XM, Flexible Lighting Management Unit is ideal
for lighting-management of mobile telephones and other 1-cell
Li+ or 3-cell NiMH powered devices.
Page 2
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − General Description
Block Diagram
The functional blocks of this device are shown below:
Figure 2:
AS3687/87XM Block Diagram
Battery
C6
1μF
L1
10μH
DCDC_GATE
AS3687/
AS3687
AS3687XM
Lighting
Lighting
Management
Management
Unit
Unit
LED
Test
V2_5
References
and
Temperature
Supervision
C1
1μF
C9
4.7μF
Q1
DCDC_SNS
Step Up DC/DC
Converter
R1
0.1ȍ
R2
1Mȍ
C7
1.5nF
R3
100kȍ
C8
15nF
DCDC_FB
Battery
8Bit PWM
Generator
Automatic Dimming
and LED Pattern
Generator
VBAT
D1
VBAT
C2_P
Charge Pump
1:1, 1:1.5, 1:2
C3
500nF
C2_N
C2
1μF
C1_P
D6
D9
D12
D7
D10
D13
D8
D11
D14
C4
500nF
150mA
C1_N
CPOUT
Zero Power
Device
Wakeup
Current Sinks
each 0.15-38.25mA
VDD_I/F
R4
1-10kȍ
DATA
CLK
D2
CURR30
D3
D4
D5
C5
1.0μF
CURR31
R5
DATA
CURR32
Serial
Interface
CLK
CURR33
HV Current Sinks
each 0.15-38.25mA
ADC
vtemp
currx
dcdc
CURR1
CURR2
CURR6
VSS
ams Datasheet
[v3-05] 2015-Oct-23
Page 3
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AS3687/87XM − General Description
Figure 3:
Application Diagram of the AS3687XM
Alternative:
use DCDC step up
C6 for CURR1,2,6
1μF
L1
10μH
DCDC_GATE
AS3687XM
Lighting
Management
Unit
LED
Test
V2_5
References
and
Temperature
Supervision
C1
1μF
C9
4.7μF
Q1
DCDC_SNS
Step Up DC/DC
Converter
R1
0.1ȍ
R2
1Mȍ
C7
1.5nF
DCDC_FB
C8
15nF
8Bit PWM
Generator
Automatic Dimming
and LED Pattern
Generator
VBAT
D1
VBAT
Battery
C2_P
Charge Pump
1:1, 1:1.5, 1:2
C2_N
C3
500nF
C2
1μF
C1_P
150mA
C1_N
C4
500nF
CPOUT
Zero Power
Device
Wakeup
Current Sinks
each 0.15-38.25mA
R4
1-10kȍ
CLK
C5
1.0μF
CURR30
VDD_I/F
DATA
DRGB1
CURR31
DATA
CURR32
Serial
Interface
CLK
CURR33/AUDIO_IN
C10
100nF
Audio IN
Alternative:
2nd Audio or Backlight
Audio Processing
ADC
vtemp
currx
dcdc
HV Current Sinks
each 0.15-38.25mA
DRGB2
D2
D3
D4
CURR1
CURR2
CURR6
VSS
Page 4
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Pin Assignment
Pin Assignment
Pin Description
Figure 4:
Pin List WL-CSP 4×5 Balls
Bmp
Name
Typ
Description
A1
C2_N
AIO
Charge Pump flying capacitor; connect a ceramic capacitor of 500nF to
this pin.
A2
C1_P
AIO
Charge Pump flying capacitor; connect a ceramic capacitor of 500nF to
this pin.
A3
CP_OUT
AO
Output voltage of the Charge Pump; connect a ceramic capacitor of
1μF (±20%).
A4
DATA
DIO
Serial interface data input/output.
B1
C1_N
AIO
Charge Pump flying capacitor; connect a ceramic capacitor of 500nF to
this pin.
B2
C2_P
AIO
Charge Pump flying capacitor; connect a ceramic capacitor of 500nF to
this pin.
B3
DCDC_GATE
AO
DC/DC gate driver.
B4
CLK
DI
Clock input for serial interface.
C1
VSS
GND
C2
VBAT
S
Supply pad. Connect to battery.
C3
CURR30
AI
Analog current sink input, intended for activity icon LED
C4
DCDC_SNS
AI
Sense input of shunt resistor for Step Up DC/DC Converter.
CURR33
D1
CURR33
/AUDIO_IN
Ground pad
AS3687: Analog current sink input, intended for activity icon LED
AI
AS3687XM: Analog current sink input, intended for activity icon LED or
audio signal input
D2
CURR31
AI
D3
CURR2
AI_HV
D4
DCDC_FB
AI
DC/DC feedback. Connect to resistor string.
E1
CURR32
AI
Analog current sink input, intended for activity icon LED
E2
CURR6
AI_HV
Analog current sink input (intended for Keyboard backlight)
E3
CURR1
AI_HV
Analog current sink input (intended for Keyboard backlight)
E4
V2_5
AO3
ams Datasheet
[v3-05] 2015-Oct-23
Analog current sink input, intended for activity icon LED
Analog current sink input (intended for Keyboard backlight)
Output voltage of the Low-Power LDO; always connect a ceramic
capacitor of 1μF (±20%) or 2.2μF (+100%/-50%).
Do not load this pin during device startup.
Page 5
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AS3687/87XM − Pin Assignment
Abbreviations for Pin Types in Figure 4:
Page 6
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DI
: Digital Input
DO
: Digital Output
DIO
: Digital Input/Output
AIO
: Analog Pad
AI
: Analog Input
AI_HV
: High-Voltage (15V) Pin
AO3
: Analog Output (3.3V)
S
: Supply Pad
GND
: Ground Pad
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Absolute Maximum Ratings
Absolute Maximum Ratings
Stresses beyond those listed in Absolute Maximum Ratings may
cause permanent damage to the device.These are stress ratings
only, and functional operation of the device at these or any
other conditions beyond those indicated in Electrical
Characteristics is not implied. Exposure to absolute maximum
rating conditions may affect device reliability.
Figure 5:
Absolute Maximum Ratings
Symbol
VIN_HV
Parameter
15V Pins
Min
Max
Units
Comments
-0.3
17
V
Applicable for high-voltage current
sink pins CURR1,CURR2, CURR6
VIN_MV
5V Pins
-0.3
7.0
V
Applicable for 5V pins
VBAT, CURR30-33,
CURR33/AUDIO_IN, C1_N, C2_N, C1_P ,
C2_P , CPOUT, DCDC_FB,
DCDC_GATE, CLK, DATA;
VIN_LV
3.3V Pins
-0.3
5.0
V
Applicable for 3.3V pins
V2_5; DCDC_SNS
Input Pin Current
-25
+25
mA
At 25°C, Norm: JEDEC 17
Tstrg
Storage Temperature Range
-55
125
°C
RHNC
Relative Humidity
(non-condensing)
5
85
%
IIN
ESDHBM
ESDCDM
Electrostatic Discharge Norm:
MIL 883 E Method 3015
Norm: JEDEC JESD 22-A115-A
level A
±2000
V
All pins except
CURR33/AUDIO_IN
±1000
V
Pin CURR33/AUDIO_IN
±500
V
Pt
Total Power Dissipation
0.75
W
TA = 70 °C, Tjunc_max = 125°C
TBODY
Peak Body Temperature
260
°C
t = 20s to 40s, in accordance with
IPC/JEDEC J-STD 020.
MSL
Moisture sensitivity level
ams Datasheet
[v3-05] 2015-Oct-23
1
Maximum floor life time of
unlimited hours
Page 7
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AS3687/87XM − Electrical Characteristics
Electrical Characteristics
Figure 6:
Operating Conditions
Symbol
Parameter
Min
Note
V
3.6
5.5
V
VBAT
1.5
1.8 / 2.8
5.5
V
For serial interface pins.
Voltage on Pin V2_5
2.4
2.5
2.6
V
Internally generated
Operating
Temperature Range
-30
25
85
°C
0.0
VBAT
Battery Voltage
3.0
VDDI/F
Interface Supply
Voltage
V2_5
TAMB
ISHUTDOWN
Units
15.0
High Voltage
ISTANDBY
Max
Applicable for high-voltage
current sink pins CURR1,
CURR2 and CURR6.
VHV
IACTIVE
Typ
Battery current
70
Standby Mode Current
5.8
Shutdown Mode
Current
0.1
Page 8
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μA
Normal Operating current –
(see Operating Modes);
interface active (excluding
current of the enabled
blocks)
13
μA
Current consumption in
standby mode. Only 2.5V
regulator ON, interface active
3
μA
Interface inactive (CLK and
DATA set to 0V)
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Typical Operating Characteristics
Typical Operating
Characteristics
Typical conditions are measured at 25°C and 3.6V
(unless otherwise noted).
Figure 7:
DC/DC Step Up Converter: Efficiency of +15V Step Up to 15V
vs. Load Current at VBAT = 3.8V
90
VOUT=14.2V
VOUT=14.2V
fclk=550kHz
Efficiency of DCDC [%]
85
VOUT=22V
VOUT=17.2V
80
75
70
65
0
0.01
0.02
0.03
0.04
0.05
0.06
Load Current [A]
Figure 8:
Charge Pump: Efficiency vs. VBAT
100
ILOAD=150mA
90
Efficiency of CP [%]
80
70
60
50
ILOAD=80mA
40
ILOAD=40mA
30
20
10
0
2.8
3
3.2
3.4
3.6
3.8
4
4.2
VBAT [V]
ams Datasheet
[v3-05] 2015-Oct-23
Page 9
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AS3687/87XM − Typical Operating Characteristics
Figure 9:
Charge Pump: Battery Current vs. VBAT
250
200
IBat[mA]
ILOAD=150mA
150
100
ILOAD=80mA
ILOAD=40mA
50
0
2.8
3
3.2
3.4
3.6
VBat[V]
3.8
4
4.2
Figure 10:
Current Sink CURR1 vs. V(CURRx)
40.0
ICURR1=38.25mA
35.0
ICURR1 [mA]
30.0
25.0
ICURR1=19.2mAm
20.0
15.0
10.0
5.0
ICURR1=2.4mA
0.0
0.0
0.5
1.0
1.5
2.0
VCURR1 [V]
Page 10
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Typical Operating Characteristics
Figure 11:
Current Sink CURR1 Protection Current
3,0
curr_prot1_on=1
Current [mA]
2,5
2,0
1,5
1,0
4.5uA
0,5
curr_prot1_on=0
0,0
0,0
5,0
10,0
15,0
20,0
V(CURR1) [V]
Protection Current vs. Voltage (curr sinks off, curr_protX_on=0/1).
Figure 12:
Current Sink CURR3x vs. VBAT
40.0
ICURR30=38.25mA
35.0
ICURR30 [mA]
30.0
25.0
ICURR30=19.2mAm
20.0
15.0
10.0
5.0
ICURR30=2.4mA
0.0
0.0
0.5
1.0
1.5
2.0
VCURR30 [V]
ams Datasheet
[v3-05] 2015-Oct-23
Page 11
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AS3687/87XM − Typical Operating Characteristics
Figure 13:
Charge Pump Input and Output Ripple 1:1.5 Mode,
100mA load
VBAT,
20mV/div,
AC-coupled
V(CPOUT),
100mV/div,
AC-coupled
250ns/div
Measured with battery (3.8V) on demoboard
Figure 14:
Charge Pump Input and Output Ripple 1:2 Mode,
100mA load
VBAT,
20mV/div,
AC-coupled
V(CPOUT),
20mV/div,
AC-coupled
250ns/div
Measured with battery (3.0V) on demoboard
Page 12
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Detailed Functional
Description
Step Up DC/DC Converter
The Step Up DC/DC Converter is a high-efficiency current mode
PWM regulator, providing output voltage up to e.g. 25V/35mA
or e.g. 16V/55mA. A constant switching-frequency results in a
low noise on the supply and output voltages.
Figure 15:
Step Up DC/DC Converter Block Diagram
Battery
C6
1μF
L1
10μH
DCDC_GATE
D1
C9
4.7μF
Q1
DCDC_SNS
Step Up DC/DC
Converter
R1
R2
1M
C7
1.5nF
R3
100k
C8
15nF
DCDC_FB
HV Current Sinks
each 0.156-40mA
D6
D9
D12
D7
D10
D13
D8
D11
D14
CURR1
CURR2
CURR6
Option: Current Feedback with Overvoltage Protection.
ams Datasheet
[v3-05] 2015-Oct-23
Page 13
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AS3687/87XM − Detailed Functional Description
Figure 16:
Step Up DC/DC Converter Parameters
Symbol
Parameter
Min
Typ
Max
Unit
μA
IVDD
Quiescent Current
VFB1
Feedback Voltage for
External Resistor Divider
1.20
1.25
1.30
V
For constant voltage control.
step_up_res = 1
VFB2
Feedback Voltage for
Current Sink Regulation
0.4
0.5
0.6
V
On CURR1, CURR2 or CURR6 in
regulation.
step_up_res = 0
IDCDC_FB
Additional Tuning Current
at Pin DCDC_FB and
overvoltage protection
0
31
μA
Accuracy of Feedback
Current at full scale
-6
6
%
Vrsense_
max
Vrsense_
max_start
140
Note
Current Limit Voltage at
RSENSE (R1)
Vrsense_
max_lc
RSW
Switch Resistance
Iload
Load Current
46
66
85
25
33
43
30
43
57
1
0
Cout
L
tMIN_ON
MDC
Switching Frequency
Output Capacitor
mV
Ω
At 16V output voltage.
0.9
35
1
4.7
Inductor
7
10
Minimum ON Time
90
140
Maximum Duty Cycle
88
91
1.1
At 25V output voltage.
MHz
μF
13
μH
Use inductors with small
Cparasitic (<100pF) to get high
efficiency.
190
ns
%
160
mV
Voltage ripple <20kHz
40
mV
85
Internally trimmed.
Ceramic, ±20%. Use nominal
4.7μF capacitors to obtain at
least 0.7μF under all
conditions (voltage
dependance of capacitors)
Voltage ripple >20kHz
Page 14
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ON-resistance of external
switching transistor.
mA
0.7
Efficiency
For fixed startup time of 500μs
If stepup_lowcur= 1
Vripple
Efficiency
Adjustable by software using
Register DCDC control1 1μA
step size (0-15μA)
VPROTECT = 1.25V +
IDCDC_FB * R2
e.g., 0.66A for 0.1Ω sense
resistor
55
0
fIN
Pulse skipping mode.
%
Cout=4.7μF, Iout=0 to 45mA,
Vbat=3.0 to 4.2V
Iout=20mA,Vout=17V,
Vbat=3.8V
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
To ensure soft startup of the DC/DC converter, the overcurrent
limits are reduced for a fixed time after enabling the DC/DC
converter. The total startup time for an output voltage of e.g.
25V is less than 2ms.
Feedback Selection
Register 21h (DC/DC Control1) selects the type of feedback for
the Step Up DC/DC Converter.
The feedback for the DC/DC converter can be selected either
by current sinks (CURR1, CURR2, CURR6) or by a voltage
feedback at pin DCDC_FB. If the register bit step_up_fb_auto is
set, the feedback path is automatically selected between
CURR1, CURR2 and CURR6 (the lowest voltage of these current
sinks is used).
Setting step_up_fb enables feedback on the pins CURR1,
CURR2 or CURR6. The Step Up DC/DC Converter is regulated
such that the required current at the feedback path can be
supported. (Bit step_up_res should be set to 0 in this
configuration)
Note(s): Always choose the path with the highest voltage drop
as feedback to guarantee adequate supply for the other
(unregulated) paths or enable the register bit step_up_fb_auto.
Overvoltage Protection in Current Feedback Mode
The overvoltage protection in current feedback mode
(step_up_fb = 01, 10 or 11 or step_up_fb_auto = 1) works as
follows: Only resistor R3 and C10/C11 is soldered and R4 is
omitted. An internal current source (sink) is used to generate a
voltage drop across the resistor R3. If then the voltage on
DCDC_FB is above 1.25V, the DC/DC is momentarily disabled to
avoid too high voltages on the output of the DC/DC converter.
The protection voltage can be calculated according to the
following formula:
(EQ1)
V PROTECT = 1.25V + IDCDC_FB * R 2
Note(s):
• The voltage on the pin DCDC_FB is limited by an internal
protection diode to VBAT + one diode forward voltage
(typ. 0.6V).
• If the overvoltage protection is not used in current
feedback mode, connect DCDC_FB to ground.
ams Datasheet
[v3-05] 2015-Oct-23
Page 15
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AS3687/87XM − Detailed Functional Description
Figure 17:
Step Up DC/DC Converter Detail Diagram
Battery
C6
1μF
L1
10μH
step_up_freq
clk
PWM
Logic
pulse_skip
overshoot
ov_voltage
1MHz
500kHz
V
Vrsense_max
R1
step_up_vtuning
R2
1M
C7
1.5nF
R3
100k
C8
15nF
DCDC_FB
1.25V
overshoot comp
error ota
step_up_fb_auto
C9
4.7μF
Q1
DCDC_SNS
ov_curr
step_up_prot
ramp
DCDC_GATE
Gate
Driver
D1
D6
D9
D12
1.35V
0.8V
D7
D10
D13
1.25V
0.5V
D8
D11
D14
step_up_fb
HV Current Sinks
each 0.156-40mA
Automatic
feedback select
(CURR1,2,6)
CURR1
CURR2
CURR6
CURRX on and
currX_on_cp=0
Option: Regulated Output Current, Feedback is automatically selected between CURR1, CURR2, CURR6
(step_up_fb_auto=1); overvoltage protection is enabled (step_up_prot=1); 1MHz clock frequency
(step_up_freq=0).
Voltage Feedback
Setting bit step_up_fb = 00 enables voltage feedback at pin
DCDC_FB.
The output voltage is regulated to a constant value, given by
(Bit step_up_res should be set to 1 in this configuration).
(EQ2)
Ustepup_out = (R2 + R3)/R3 * 1.25 + I DCDC_FB * R 2
If R 3 is not used, the output voltage is by (Bit step_up_res should
be set to 0 in this configuration):
(EQ3)
Page 16
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Ustepup_out = 1.25 + IDCDC_FB * R 2
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Where:
U stepup_out = Step Up DC/DC Converter output voltage
R2 = Feedback resistor R2
R3 = Feedback resistor R3
I DCDC_FB = Tuning current at pin 29 (DCDC_FB); 0 to 31μA
Figure 18:
Voltage Feedback Example Values
Ivtuning
Ustepup_out
μA
R2 = 1MΩ, R3
Not Used
R2 = 500kΩ,
R3 = 50kΩ
0
-
13.75
1
-
14.25
2
-
14.75
3
-
15.25
4
-
15.75
5
6.25
16.25
6
7.25
16.75
7
8.25
17.25
8
9.25
17.75
9
10.25
18.25
10
11.25
18.75
11
12.25
19.25
12
13.25
19.75
13
14.25
20.25
14
15.25
20.75
15
16.25
21.25
…
…
…
30
31.25
28.75
31
32.25
29.25
Caution: The voltage on CURR1, CURR2 and CURR6 must not
exceed 15V – see also section High Voltage Current Sinks.
ams Datasheet
[v3-05] 2015-Oct-23
Page 17
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AS3687/87XM − Detailed Functional Description
PCB Layout Hints
To ensure good EMC performance of the DC/DC converter, keep
its external power components C2, R2, L1, Q1, D1 and C9 close
together. Connect the ground of C2, Q1 and C9 locally together
and connect this path with a single via to the main ground
plane. This ensures that local high-frequency currents will not
flow to the battery.
Step Up Registers
Reg. Control Register (Address 00h)
Figure 19:
Reg. Control Register
Reg. Control
Addr: 00
This register enables/disables the Charge Pump and the Step Up
DC/DC Converter
Bit
Bit Name
Default
Access
3
step_up_on
0
R/W
Page 18
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Description
Enable the step up converter
0 = Disable the Step Up DC/DC Converter.
1 = Enable the Step Up DC/DC Converter.
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
DCDC Control1 Register (Address 21h)
Figure 20:
DC/DC Control1 Register
DC/DC Control1
Addr: 21h
This register controls the Step Up DC/DC Converter
Bit
0
2:1
7:3
Bit Name
step_up_frequ
step_up_fb
step_up_
vtuning
ams Datasheet
[v3-05] 2015-Oct-23
Default
0
00
00000
Access
Description
R/W
Defines the clock frequency of the Step Up DC/DC
Converter.
0 = 1 MHz
1 = 500 kHz
R/W
Controls the feedback source if step_up_fb_auto = 0
00 = DCDC_FB enabled (external resistor divider). Set
step_up_fb=00 (DCDC_FB), if external PWM is enabled for
CURR1, CURR2 or CURR6
01 = CURR1 feedback enabled (feedback via white LEDs).
10 = CURR2 feedback enabled (feedback via white LEDs).
11 = CURR6 feedback enabled (feedback via white LEDs).
R/W
Defines the tuning current at pin DCDC_FB.
00000 = 0 μA
00001 = 1 μA
00010 = 2 μA
…
10000 = 15 μA
…
11111 = 31 μA
Page 19
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AS3687/87XM − Detailed Functional Description
DC/DC Control2 Register (Address 22h)
Figure 21:
DC/DC Control2 Register
DC/DC Control2
Addr: 22h
Bit
0
1
Bit Name
step_up_res
skip_fast
This register controls the Step Up DC/DC Converter and
low-voltage current sinks CURR3x
Default
0
0
Access
Description
R/W
Gain selection for Step Up DC/DC Converter.
0 = Select 0 if Step Up DC/DC Converter is used with
current feedback (CURR1, CURR2, CURR6) or if DCDC_FB
is used with current feedback only – only R1, C1
connected.
1 = Select 1 if DCDC_FB is used with external resistor
divider (2 resistors).
R/W
Step Up DC/DC Converter output voltage at low loads,
when pulse skipping is active.
0 = Accurate output voltage, more ripple.
1 = Elevated output voltage, less ripple.
2
step_up_prot
1
R/W
Step Up DC/DC Converter protection.
0 = No overvoltage protection.
1 = Overvoltage protection on pin DCDC_FB enabled
voltage limitation =1.25V on DCDC_FB.
3
stepup_lowcur
1
R/W
Step Up DC/DC Converter coil current limit.
0 = Normal current limit.
1 = Current limit reduced by approx. 33%.
4
curr1_prot_on
0
R/W
0 = No overvoltage protection .
1 = Pull down current switched ON, if voltage exceeds
13.75V, and step_up_on=1.
5
curr2_prot_on
0
R/W
0 = No overvoltage protection.
1 = Pull down current switched ON, if voltage exceeds
13.75V, and step_up_on=1.
6
curr6_prot_on
0
R/W
0 = No overvoltage protection.
1 = Pull down current switched ON, if voltage exceeds
13.75V, and step_up_on=1.
R/W
0 = step_up_fb select the feedback of the DC/DC
converter.
1 = The feedback is automatically chosen within the
current sinks CURR1, CURR2 and CURR6 (never
DCDC_FB).
Only those are used for this selection, which are
enabled (currX_mode must not be 00) and not
connected to the charge pump (currX_on_cp must be
0). Don’t use automatic feedback selection together
with external PWM for the current sources CURR1,
CURR2 or CURR6.
7
step_up_fb_auto
Page 20
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0
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Charge Pump
The Charge Pump uses two external flying capacitors C6, C7 to
generate output voltages higher than the battery voltage.
There are three different operating modes of the charge pump
itself:
• 1:1 Bypass Mode
• Battery input and output are connected by a
low-impedance switch.
• Battery current = output current.
• 1:1.5 Mode
• The output voltage is up to 1.5 times the battery
voltage (without load), but is limited to VCPOUTmax
all the time.
• Battery current = 1.5 times output current.
• 1:2 Mode
• The output voltage is up to 2 times the battery voltage
(without load), but is limited to VCPOUTmax all the
time.
• Battery current = 2 times output current
ams Datasheet
[v3-05] 2015-Oct-23
Page 21
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AS3687/87XM − Detailed Functional Description
As the battery voltage decreases, the Charge Pump must be
switched from 1:1 mode to 1:1.5 mode and eventually in 1:2
mode in order to provide enough supply for the current sinks.
Depending on the actual current the mode with best overall
efficiency can be automatically or manually selected:
Examples:
• Battery voltage = 3.7V, LED dropout voltage = 3.5V. The
1:1 mode will be selected and there is 200mV drop on the
current sink and on the Charge Pump switch. Efficiency
95%.
• Battery voltage = 3.5V, LED dropout voltage = 3.5V. The
1:1.5 mode will be selected and there is 1.5V drop on the
current sink and 250mV on the Charge Pump. Efficiency
66%.
• Battery voltage = 3.8V, LED dropout voltage = 4.5V
(Camera Flash). The 1:2 mode can be selected and there is
600mV drop on the current sink and 2.5V on the Charge
Pump. Efficiency 60%.
The efficiency is dependent on the LED forward voltage given
by:
(EQ4)
E ff = (VLED * I out)/(Uin * I in)
The charge pump mode switching can be done manually or
automatically with the following possible software settings:
• Automatic up all modes allowed (1:1, 1:1.5, 1:2)
• Start with 1:1 mode
• Switch up automatically 1:1 to 1:1.5 to 1:2
• Automatic up, but only 1:1 and 1:1.5 allowed
• Start with 1:1 mode
• Switch up automatically only from 1:1 to 1:1.5 mode;
1:2 mode is not used
• Manual
• Set modes 1:1, 1:1.5, 1:2 by software
Page 22
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 22:
Charge Pump Pin Connections
Battery
VBAT
C2
1μF
C2_P
Charge Pump
C2_N
1:1, 1:1.5, 1:2
C3
500nF
C1_P
150mA
C1_N
C4
500nF
CPOUT
C5
1.0μF
The Charge Pump requires the external components listed in
the following table:
Figure 23:
Charge Pump External Components
Symbol
Parameter
C2
External Decoupling
Capacitor
C3, C4
C5
Min
Typ
Max
1.0
Unit
Note
μF
Ceramic low-ESR capacitor between
pins VBAT and VSS.
External Flying
Capacitor (2x)
500
nF
Ceramic low-ESR capacitor between
pins C1_P and C1_N, between pins
C2_P and C2_N and between VBAT
and VSS.
External Storage
Capacitor
1.0
μF
Ceramic low-ESR capacitor between
pins CP_OUT and VSS. Use nominal
1μF capacitors (size 0603)
Note(s) and/or Footnote(s):
1. The connections of the external capacitors C2, C3, C4 and C5 should be kept as short as possible.
2. The maximum voltage on the flying capacitors C3 and C4 is VBAT.
ams Datasheet
[v3-05] 2015-Oct-23
Page 23
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AS3687/87XM − Detailed Functional Description
Figure 24:
Charge Pump Characteristics
Symbol
Parameter
ICPOUT
Output Current
Continuous
VCPOUTmax
Output Voltage
η
ICP1_1.5
Efficiency
Min
Typ
0.0
60
Max
Unit
Note
150
mA
5.5
V
Internally limited, Including
output ripple
90
%
Including current sink loss;
ICPOUT < 100mA.
Depending on PCB layout
Power Consumption
without Load
fclk = 1 MHz
3.4
0.57
Ω
1:1 Mode; VBAT ≥ 3.5V
Rcp1_1.5
Effective Charge
Pump Output
Resistance
2.65
Ω
1:1.5 Mode; VBAT ≥ 3.3V
Rcp1_2
(Open Loop, fclk =
1MHz)
3.25
Ω
1:1.2 Mode; VBAT ≥ 3.1V
fclk Accuracy
Accuracy of Clock
Frequency
currhv_switch
Vcurr3x_switch
ICP1_2
Rcp1_1
tdeb
Page 24
Document Feedback
1:1.5 Mode
mA
3.8
10
%
CURR1, 2, 6
minumum voltage
0.45
V
CURR30-33
minumum voltage
0.2
V
If the voltage drops below this
threshold, the charge pump will
use the next available mode
(1:1 -> 1:1.5 or 1:1.5 -> 1:2)
240
μs
cp_start_debounce=0
2000
μs
After switching ON CP (cp_on set
to 1), if cp_start_debounce=1
CP automatic
up-switching
debounce time
-10
1:2 Mode
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Charge Pump Mode Switching
If automatic mode switching is enabled (cp_mode_switching =
00 or cp_mode_switching = 01) the charge pump monitors the
current sinks, which are connected via an LED to the output
CP_OUT. To identify these current sources (sinks), the registers
cp_mode_switch1 and cp_mode_switch2 (register bits
curr30_on_cp to curr33_on_cp, curr1_on_cp, curr2_on_cp,
curr6_on_cp) should be setup before starting the charge pump
(cp_on = 1). If any of the voltage on these current sources drops
below the threshold (currlv_switch, currhv_switch,
curr3x_switch), the next higher mode is selected after the
debounce time. To avoid switching into 1:2 mode (battery
current = 2 times output current), set cp_mode_switching = 10.
If the currX_on_cp=0 and the according current sink is
connected to the chargepump, the current sink will be
functional, but there is no up switching of the charge pump, if
the voltage compliance is too low for the current sink to supply
the specified current.
Figure 25:
Automatic Mode Switching
Battery
VBAT
C2
1μF
C2_P
Mode Switching
cp_mode<1:0>
1:1 -> 1:1.5
1:1.5 -> 1:2
Charge Pump
1:1, 1:1.5, 1:2
C2_N
C3
500nF
C1_P
C1_N
C4
500nF
CPOUT
C5
1.0μF
curr30_on_cp
curr31_on_cp
Debounce
CURR30
200mV
(curr3x_switch)
curr32_on_cp
CURR32
curr33_on_cp
CURR33
curr1_on_cp
curr2_on_cp
curr6_on_cp
ams Datasheet
[v3-05] 2015-Oct-23
CURR31
CURR1
450mV
(currhv_switch)
CURR2
CURR6
Page 25
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AS3687/87XM − Detailed Functional Description
Soft Start
An implemented soft start mechanism reduces the inrush
current. Battery current is smoothed when switching the charge
pump ON and also at each switching condition. This precaution
reduces electromagnetic radiation significantly.
Charge Pump Registers
Figure 26:
Reg. Control Register
Reg. Control
Addr: 00h
Bit
2
Bit Name
cp_on
Page 26
Document Feedback
This register enables/disables the Charge Pump and the Step Up
DC/DC Converter
Default
0
Access
R/W
Description
0 = Set Charge Pump into 1:1 mode (OFF state) unless
cp_auto_on is set.
1 = Enable manual or automatic mode switching – see
CP Control Register for actual settings.
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 27:
CP Control Register
CP Control
Addr: 23h
This register controls the Charge Pump
Bit
Bit Name
Default
Access
0
cp_clk
0
R/W
Clock frequency selection.
0 = 1 MHz
1 = 500 kHz
R/W
Charge Pump mode (in manual mode sets this mode,
in automatic mode reports the actual mode used). (2)
00 = 1:1 mode
01 = 1:1.5 mode
10 = 1:2 mode
11 = NA
R/W
Set the mode switching algorithm:
00 = Automatic Mode switching; 1:1, 1:1.5 and 1:2
allowed (1).
01 = Automatic Mode switching; only 1:1 and 1:1.5
allowed (1).
10 = Manual Mode switching; register cp_mode
defines the actual charge pump mode used.
11 = reserved.
R/W
0 = Mode switching debounce timer is always 240μs.
1 = Upon startup (cp_on set to 1) the mode switching
debounce time is first started with 2ms then reduced
to 240μs .
R/W
0 = Charge Pump is switched ON/OFF with cp_on.
1 = Charge Pump is automatically switched ON if a
current sink, which is connected to the charge pump
(defined by registers CP Mode Switch 1 & 2) is
switched ON.
2:1
4:3
5
6
cp_mode
cp_mode_switching
cp_start_debounce
cp_auto_on
00
00
0
0
Description
Note(s) and/or Footnote(s):
1. Don’t use automatic mode switching together with external PWM for the current sources connceted to the charge pump with less
than 500μs high time.
2. Direct switching from 1:1.5 mode into 1:2 in manual mode and vice versa is not allowed. Always switch over 1:1 mode.
ams Datasheet
[v3-05] 2015-Oct-23
Page 27
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AS3687/87XM − Detailed Functional Description
Figure 28:
CP Mode Switch1 Register
CP Mode Switch1
Addr: 24h
Setup which current sinks are connected (via LEDs) to the charge
pump; if set to ‘1’ the correspond current source (sink) is used for
automatic mode selection of the charge pump
Bit
Bit Name
Default
Access
Description
0
curr30_on_cp
0
R/W
0 = Current sink CURR30 is not connected to charge pump
1 = Current sink CURR30 is connected to charge pump
1
curr31_on_cp
0
R/W
0 = Current sink CURR31 is not connected to charge pump
1 = Current sink CURR31 is connected to charge pump
2
curr32_on_cp
0
R/W
0 = Current sink CURR32 is not connected to charge pump
1 = Current sink CURR32 is connected to charge pump
3
curr33_on_cp
0
R/W
0 = Current sink CURR33 is not connected to charge pump
1 = Current sink CURR33 is connected to charge pump
Figure 29:
CP Mode Switch2 Register
CP Mode Switch2
Addr: 25h
Setup which current sinks are connected (via LEDs) to the charge
pump; if set to ‘1’ the correspond current source (sink) is used for
automatic mode selection of the charge pump
Bit
Bit Name
Default
Access
Description
0
curr1_on_cp
0
R/W
0 = Current sink CURR1 is not connected to charge pump
1 = Current sink CURR1 is connected to charge pump
1
curr2_on_cp
0
R/W
0 = Current sink CURR2 is not connected to charge pump
1 = Current sink CURR2 is connected to charge pump
7
curr6_on_cp
0
R/W
0 = Current sink CURR6 is not connected to charge pump
1 = Current sink CURR6 is connected to charge pump
Page 28
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 30:
Curr Low Voltage Status1 Register
Curr Low Voltage Status1
Addr: 2Ah
Indicates the low voltage status of the current sinks. If the
currX_low_v bit is set, the voltage on the current sink is too low, to
drive the selected output current
Bit
Bit Name
Default
Access
0
curr30_low_v
1
R
0 = Voltage of current sink CURR30 >curr3x_switch
1 = Voltage of current sink CURR30 <curr3x_switch
1
curr31_low_v
1
R
0 = Voltage of current sink CURR31 >curr3x_switch
1 = Voltage of current sink CURR31 <curr3x_switch
2
curr32_low_v
1
R
0 = Voltage of current sink CURR32 >curr3x_switch
1 = Voltage of current sink CURR32 <curr3x_switch
3
curr33_low_v
1
R
0 = Voltage of current sink CURR33 >curr3x_switch
1 = Voltage of current sink CURR33 <curr3x_switch
7
curr6_low_v
0
R
0 = Voltage of current sink CURR6 >currlv_switch
1 = Voltage of current sink CURR6 <currlv_switch
ams Datasheet
[v3-05] 2015-Oct-23
Description
Page 29
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AS3687/87XM − Detailed Functional Description
Figure 31:
Curr Low Voltage Status2 Register
Curr Low Voltage Status2
Addr: 2Bh
Indicates the low voltage status of the current sinks. If the
currX_low_v bit is set, the voltage on the current sink is too low, to
drive the selected output current
Bit
Bit Name
Default
Access
Description
0
curr1_low_v
0
R
0 = Voltage of current sink CURR1 >currhv_switch.
1 = Voltage of current sink CURR1 <currhv_switch.
1
curr2_low_v
0
R
0 = Voltage of current sink CURR2 >currhv_switch.
1 = Voltage of current sink CURR2 <currhv_switch.
Current Sinks
The AS3687/87XM contains general purpose current sinks
intended to control backlights, buzzers, and vibrators.
All current sinks have an integrated protection against
overvoltage.
CURR1, CURR2 and CURR6 is also used as feedback for the Step
Up DC/DC Converter (regulated to 0.5V in this configuration).
• Current sinks CURR1, CURR2 and CURR6 are high-voltage
compliant (15V) current sinks, used e.g., for series of white
LEDs.
• Current sinks CURR3x (CURR30, CURR31, CURR32 and
CURR33) are parallel 5V current sinks, used for
backlighting or indicator LEDs.
Page 30
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
High Voltage Current Sinks CURR1, CURR2, CURR6
The high voltage current sinks have a resolution of 8 bits.
Additionally an internal protection circuit monitors with a
voltage divider (max 3μA @ 15) the voltage on CURR1, CURR2
and CURR6 and increases the current in OFF state in case of
overvoltage.
Figure 32:
HV - Current Sinks Characteristics
Symbol
Parameter
Min
Typ
IBIT7
Current sink if Bit7 = 1
19.2
IBIT6
Current sink if Bit6 = 1
9.6
IBIT5
Current sink if Bit5 = 1
4.8
IBIT4
Current sink if Bit4 = 1
2.4
IBIT3
Current sink if Bit3 = 1
1.2
IBIT2
Current sink if Bit2 = 1
0.6
IBIT1
Current sink if Bit1 = 1
0.3
IBIT0
Current sink if Bit0 = 1
0.15
Δm
Matching Accuracy
-10
Δ
Absolute Accuracy
VCURRx
Voltage compliance
Ov_prot_
13V
Overvoltage Protection of
current sink CURR1,2,6
Ov_prot_
15V
Overvoltage Protection of
current sink CURR1,2,6
ams Datasheet
[v3-05] 2015-Oct-23
Max
Unit
Note
mA
For V(CURRx) > 0.45V
+10
%
CURR1,CURR2,CURR6
-15
+15
%
0.45
15
V
3.0
0.8
4.0
μA
At 13V, independent of
curr1_prot_on,
curr2_prot_on or
curr6_prot_on
mA
At 15V, step_up_on=1,
curr1_prot_on=1 for CURR1,
curr2_prot_on=1 for CURR2,
curr6_prot_on=1 for CURR6
Page 31
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AS3687/87XM − Detailed Functional Description
High Voltage Current Sinks CURR1, CURR2, CURR6
Registers
Figure 33:
Curr1 Current Register
Curr1 Current
Addr: 09h
This register controls the high voltage current sink current
Bit
7:0
Bit Name
curr1_current
Default
0
Access
R/W
Description
Defines current into Current sink curr1
00h = 0 mA
01h = 0.15 mA
...
FFh = 38.25 mA
Figure 34:
Curr2 Current Register
Curr2 Current
Addr: 0Ah
This register controls the high voltage current sink current
Bit
7:0
Bit Name
curr2_current
Default
0
Access
R/W
Description
Defines current into Current sink curr2
00h = 0 mA
01h = 0.15 mA
...
FFh = 38.25 mA
Figure 35:
Curr6 Current Register
Curr6 Current
Addr: 2Fh
This register controls the high voltage current sink current
Bit
7:0
Bit Name
curr6_current
Page 32
Document Feedback
Default
0
Access
R/W
Description
Defines current into Current sink curr6
00h = 0 mA
01h = 0.15 mA
...
FFh = 38.25 mA
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 36:
Curr12 Current Register
Curr12 Current
Addr: 01h
Bit
1:0
3:2
Bit Name
curr1_mode
curr2_mode
This register select the mode of the current sinks controls high
voltage current sink current
Default
0
0
Access
Description
R/W
Select the mode of the current sink curr1
00 = OFF
01 = ON
10 = PWM controlled
11 = LED pattern controlled
R/W
Select the mode of the current sink curr2
00 = OFF
01 = ON
10 = PWM controlled
11 = LED pattern controlled
Figure 37:
Curr6 Control Register
Curr6 Control
Addr: 02h
This register select the mode of the current sinks CURR6
Bit
7:6
Bit Name
curr6_mode
ams Datasheet
[v3-05] 2015-Oct-23
Default
0
Access
R/W
Description
Select the mode of the current sink CURR6
00 = OFF
01 = ON
10 = PWM controlled
11 = LED pattern controlled
Page 33
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AS3687/87XM − Detailed Functional Description
Current Sinks CURR30, CURR31, CURR32, CURR33
These current sinks have a resolution of 8 bits and can sink up
to 40mA. The current values can be controlled individually with
curr30_current – curr33_current or common with
curr3x_strobe or curr3x_preview.
Figure 38:
Current Sinks CURR30,31,32,33 Parameters
Symbol
Parameter
Min
Typ
Max
Unit
IBIT7
Current sink if Bit7 = 1
19.2
IBIT6
Current sink if Bit6 = 1
9.6
IBIT5
Current sink if Bit5 = 1
4.8
IBIT4
Current sink if Bit4 = 1
2.4
IBIT3
Current sink if Bit3 = 1
1.2
IBIT2
Current sink if Bit2 = 1
0.6
IBIT1
Current sink if Bit1 = 1
0.3
IBIT0
Current sink if Bit0 = 1
0.15
Δm
Matching Accuracy
-10
+10
%
Δ
Absolute Accuracy
-15
+15
%
VCURR3x
Voltage compliance
0.2
CPOUT
V
mA
Note
For V(CURR3x) > 0.2V
CURR30-33
Current Sinks CURR3x Registers
Figure 39:
Curr3 Control2 Register
Curr3 Control2
Addr: 12h
This register select the modes of the current sinks 30 to 33 current
Bit
0
2:1
Bit Name
preview_off_
after strobe
preview_ctrl
Page 34
Document Feedback
Default
0
00
Access
Description
R/W
Select the switch OFF mode after strobe pulse
0 = Normal preview/strobe mode.
1 = Switch OFF preview after strobe duration has expired.
To reinitiate the torch mode the preview_ctrl has to be set
OFF and ON again.
R/W
Preview is triggered by
00 = OFF
01 = Software trigger (setting this bit automatically
triggers preview)
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 40:
Curr3 Strobe Control Register
Curr3 Strobe Control
Addr: 11h
This register select the modes of the current sinks 30 to 33 current
Bit
1:0
3:2
7:4
Bit Name
strobe_ctrl
strobe_mode
strobe_timing
Default
00
00
0000
Access
Description
R/W
Strobe is triggered by
00 = OFF
01 = Software trigger (setting this bit automatically
triggers strobe).
R/W
Selects strobe mode
00 = Mode1 (Tstrobe=Ts; strobe trigger signal ≥ 10μs).
01 = Mode 2 (Tstrobe=max Ts)
10 = Mode 3 (Tstrobe = strobe signal) .
11 = Not used.
R/W
Selects strobe time (Ts)
0000 = 100 ms
0001 = 200 ms
0010 = 300 ms
0011 = 400 ms
0100 = 500 ms
0101 = 600 ms
0110 = 700 ms
0111 = 800 ms
1000 = 900 ms
1001 = 1000 ms
1010 = 1100 ms
1011 = 1200 ms
1100 = 1300 ms
1101 = 1400 ms
1110 = 1500 ms
1111 = 1600 ms
Figure 41:
Curr3x Strobe Register
Curr3x Strobe
Addr: 0Eh
This register select the strobe current of the current sinks 30 to 33
Bit
5:0
Bit Name
curr3x_strobe
ams Datasheet
[v3-05] 2015-Oct-23
Default
00
Access
R/W
Description
Defines Strobe current of Current sinks curr30-33
00h = 0 mA
01h = 0.6 mA
...
3Fh = 37.8 mA
Page 35
Document Feedback
AS3687/87XM − Detailed Functional Description
Figure 42:
Curr3x Preview Register
Curr3x Preview
Addr: 0Fh
Bit
5:0
Bit Name
curr3x_preview
This register select the preview current of the current sinks 30 to
33
Default
00
Access
R/W
Description
Defines Preview current of Current sinks curr30-33
00h = 0 mA
01h = 0.6 mA
...
3Fh = 37.8 mA
Figure 43:
Curr3x Other Register
Curr3x Other
Addr: 10h
This register select the current of the current sinks 30 to 33
Bit
5:0
Bit Name
curr3x_other
Default
00
Access
R/W
Description
Selects curr30 current, if curr30 is not used for
strobe/preview (curr30_mode=11)
00h = 0 mA
01h = 0.6 mA
...
3Fh = 37.8 mA
Figure 44:
Curr30 Current Register
Curr30 Current
Addr: 40h
This register selects the current of the current sink 30
Bit
7:0
Bit Name
curr30_current
Page 36
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Default
00
Access
R/W
Description
Selects curr30 current, if curr30 is not used for
strobe/preview (curr30_mode=11)
00h = 0 mA
01h = 0.15 mA
...
FFh = 38.25 mA
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 45:
Curr31 Current Register
Curr31 Current
Addr: 41h
This register selects the current of the current sink 31
Bit
7:0
Bit Name
curr31_current
Default
00
Access
R/W
Description
Selects curr31 current, if curr31 is not used for
strobe/preview (curr31_mode=11)
00h = 0 mA
01h = 0.15 mA
...
FFh = 38.25 mA
Figure 46:
Curr32 Current Register
Curr32 Current
Addr: 42h
This register selects the current of the current sink 32
Bit
7:0
Bit Name
curr32_current
Default
00
Access
R/W
Description
Selects curr32 current, if curr32 is not used for
strobe/preview (curr32_mode=11)
00h = 0 mA
01h = 0.15 mA
...
FFh = 38.25 mA
Figure 47:
Curr33 Current Register
Curr33 Current
Addr: 43h
This register selects the current of the current sink 33
Bit
7:0
Bit Name
curr33_current
ams Datasheet
[v3-05] 2015-Oct-23
Default
00
Access
R/W
Description
Selects curr33 current, if curr33 is not used for
strobe/preview (curr32_mode=11)
00h = 0 mA
01h = 0.15 mA
...
FFh = 38.25 mA
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AS3687/87XM − Detailed Functional Description
Figure 48:
Curr3 Control1 Register
Curr3 Control1
Addr: 03h
This register select the mode of the current sinks 30 to 33
Bit
1:0
3:2
5:4
7:6
Bit Name
curr30_mode
curr31_mode
curr32_mode
curr33_mode
Default
0
0
0
0
Access
Description
R/W
Select the mode of the current sink curr30
00 = OFF
01 = Strobe/preview
10 = curr30_other PWM controlled
11 = curr30_current (1)
R/W
Select the mode of the current sink curr31
00 = OFF
01 = strobe/preview
10 = curr31_other PWM controlled
11 = curr31_current (1)
R/W
Select the mode of the current sink curr32
00 = OFF
01 = strobe/preview
10 = curr32_other PWM controlled
11 = curr32_current (1)
R/W
Select the mode of the current sink curr33
00 = OFF
01 = strobe/preview
10 = curr33_other PWM controlled
11 = curr33_current (1)
Note(s) and/or Footnote(s):
1. Don’t use this mode (11) if softdim_pattern=1, use strobe/preview instead.
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AS3687/87XM − Detailed Functional Description
Figure 49:
Pattern Control Register
Pattern Control
Addr: 18h
This register controls the LED pattern
Bit
Bit Name
Default
Access
Description
4
curr30_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR30 controlled according curr30_mode register. 1
= CURR30 controlled by LED pattern generator.
5
curr31_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR31 controlled according curr31_mode register. 1
= CURR31 controlled by LED pattern generator.
6
curr32_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR32 controlled according curr32_mode register.
1 = CURR32 controlled by LED pattern generator.
7
curr33_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR33 controlled according curr33_mode register.
1 = CURR33 controlled by LED pattern generator.
ams Datasheet
[v3-05] 2015-Oct-23
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AS3687/87XM − Detailed Functional Description
LED Pattern Generator
The LED pattern generator is capable of producing a pattern
with 32 bits length and 1 second duration (31.25ms for each
bit). The pattern itself can be started every second, every 2 nd,
3 rd or 4 th second.
With this pattern all current sinks can be controlled. The pattern
itself switches the configured current sources between 0 and
their programmed current.
If everything else is switched OFF, the current consumption in
this mode is I ACTIVE. (excluding current through switched ON
current source) and the charge pump, if required. The charge
pump can be automatically switched ON/OFF depending on the
pattern (see register cp_auto_on in the charge pump section)
to reduce the overall current consumption.
Figure 50:
LED Pattern Generator AS3687/87XM for pattern_color = 0
Defined by bit in the setup register pattern_data
in this example the code is 101110011...
I
any current sink
1 2 3 4 5 6 7 8 9 ... 32 1 2 3 4 5 6 7 8 9 ...
t
31.25ms
(250ms if pattern_slow=1)
At this time a delay of 0s,1s,2s,...,8s,16s,24s,32s,40s,48s,56s
can be programmed
To select the different current sinks to be controlled by the LED
pattern generator, see the ‘xxxx’_mode registers (where ‘xxxx’
stands for the to be controlled current sink, e.g. curr1_mode for
CURR1 current sink). See also the descirption of the different
current sinks.
To allow the generator of a color patterns set the bit
pattern_color to ‘1’. Then the pattern can be connected to
CURR30-32 as follows:
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AS3687/87XM − Detailed Functional Description
Figure 51:
LED Pattern Generator AS3687/87XM for pattern_color = 1
Defined by bit in the setup register pattern_data
in this example the code is 111110001011111000110111...
I
CURR1/CURR30
1 47
... 28 1 4 7
...
CURR2/CURR31
2 58
... 29 2 5 8
...
CURR6/CURR32,33
3 69
... 30 3 6 9
...
t
100ms
(800ms if pattern_slow=1)
At this time a delay of 0s,1s,2s,...,8s,16s,24s,32s,40s,48s,56s
can be programmed
Only those current sinks will be controlled, where the
‘xxxx’_mode register is configured for LED pattern.
If the register bit pattern_slow is set, all pattern times are
increased by a factor of eigth. (bit duration: 250ms if
pattern_color=0 / 800ms if pattern_color=1, delays between
pattern up to 24s).
Soft Dimming for Pattern
The internal pattern generator can be combined with the
internal PWM dimming modulator to obtain as shown in the
following figure:
Figure 52:
Soft Dimming Architecture for the AS3687/87XM (softdim_pattern=1 and pattern_color = 1)
Pattern
Generator
set
RS
reset Flip Flop
out
set
RS
reset Flip Flop
out
set
RS
reset Flip Flop
out
Zero
Detect
up down Dimming
Ramp
Gen
ams Datasheet
[v3-05] 2015-Oct-23
8
CURR1/CURR30
CURR2/CURR31
CURR6/CURR32,33
controls current sources (on/off) for
current source where
currX_mode = LED pattern
PWM
Modulator
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AS3687/87XM − Detailed Functional Description
With the AS3687/87XM smooth fade-in and fade-out effects can
be automatically generated.
As there is only one dimming ramp generator and one PWM
modulator following constraints have to be considered when
setting up the pattern (applies only if pattern_color=1):
Figure 53:
Soft Dimming Example Waveform for CURR30-32
A new dimming up (CURR32) can be
started after the dimming
down (CURR30) is finished
CURR30
ok
CURR31
ok
CURR32
not possible
A new dimming up (CURR32) cannot be
started after or while one channel (CURR30)
is dimming up
However using the identical dimming waveform for two
channels is possible as shown in the following figure:
Figure 54:
Soft Dimming Example Waveform for CURR30-32
CURR30
ok
CURR31
ok
CURR32
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ok
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
LED Pattern Registers
Figure 55:
Pattern Data Registers
Pattern Data0, Pattern Data1, Pattern Data2, Pattern Data3
Addr: 19h,1Ah,1Bh,1Ch
This registers contains the pattern data for the current sinks
Bit
Bit Name
Default
Access
Description
7:0
pattern_data0[7:0] (1)
0
R/W
Pattern Data0
7:0
pattern_data1[15:8] (1)
0
R/W
Pattern Data1
7:0
pattern_data2[23:16] (1)
0
R/W
Pattern Data2
7:0
pattern_data3[31:24] (1)
0
R/W
Pattern Data3
Note(s) and/or Footnote(s):
1. Update any of the pattern register only if none of the current sources is connected to the pattern generator (‘xxxx’_mode must not
be 11). The pattern generator is automatically started at the same time when any of the current sources is connected to the pattern
generator.
ams Datasheet
[v3-05] 2015-Oct-23
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AS3687/87XM − Detailed Functional Description
Figure 56:
Pattern Control Register
Pattern Control
Addr: 18h
This register controls the LED pattern
Bit
Bit Name
Default
Access
Description
0
pattern_color
0
R/W
Defines the pattern type for the current sinks
0 = single 32 bit pattern (also set currX_mode = 11)
1 = RGB pattern with each 10 bits
(set all currX_mode = 11)
2:1
pattern_delay
00
R/W
Delay between pattern, for details see LED Pattern
Timing; together with pattern_delay2 sets the delay time
between patterns
3
softdim_pattern
0
R/W
Enable the ‘soft’ dimming feature for the pattern
generator
0 = Pattern generator directly control current sources
1 = ‘Soft Dimming’ is performed – see Soft Dimming for
Pattern
4
curr30_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR30 controlled according curr30_mode register
1 = CURR30 controlled by LED pattern generator
5
curr31_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR31 controlled according curr31_mode register
1 = CURR31 controlled by LED pattern generator
6
curr32_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR32 controlled according curr32_mode register
1 = CURR32 controlled by LED pattern generator
7
curr33_pattern
0
R/W
Additional CURR33 LED pattern control bit
0 = CURR33 controlled according curr33_mode register
1 = CURR33 controlled by LED pattern generator
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AS3687/87XM − Detailed Functional Description
Figure 57:
GPIO Current Register
GPIO Current
Addr: 2Ch
Bit
Bit Name
Default
Access
Description
4
pattern_delay2
0
R/W
Delay between pattern see LED Pattern Timing;
together with pattern_delay sets the delay time
between patterns
R/W
Pattern timing control
0 = Normal mode
1 = Slow mode (all pattern times are increased by
a factor of eight)
6
pattern_slow
ams Datasheet
[v3-05] 2015-Oct-23
0
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AS3687/87XM − Detailed Functional Description
Figure 58:
LED Pattern Timing
pattern_
slow
pattern_
delay2
pattern_
delay
[1 to 0]
Delay Between
Patterns
Bit Duration [ms]
pattern_
color=0
pattern_
color=1
Delay[s]
Between
Pattern
Pattern Duration
(Total Cycle Time:
Pattern + Delay) [s]
0
0
00
31
100
0(1)
1
0
0
01
31
100
1
2
0
0
10
31
100
2
3
0
0
11
31
100
3
4
0
1
00
31
100
4
5
0
1
01
31
100
5
6
0
1
10
31
100
6
7
0
1
11
31
100
7
8
1
0
00
250
800
0
8
1
0
01
250
800
8
16
1
0
10
250
800
16
24
1
0
11
250
800
24
32
1
1
00
250
800
32
40
1
1
01
250
800
40
48
1
1
10
250
800
48
56
1
1
11
250
800
56
64
Note(s) and/or Footnote(s):
1. Even by setting 000 for pattern delay, there is a small delay before the new patterns starts.
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AS3687/87XM − Detailed Functional Description
PWM Generator
The PWM generator can be used for any current sink (CURR1,
CURR2, CURR3x, CURR6). The setting applies for all current sinks,
which are controlled by the PWM generator (e.g. CURR1 is PWM
controlled if curr1_mode = 10). The PWM modulated signal can
switch ON/OFF the current sinks and therefore depending on
its duty cycle change the brightness of an attached LED.
Internal PWM Generator
The internal PWM generator uses the 2MHz internal clock as
input frequency and its dimming range is 6 bits digital (2MHz /
2^6 = 31.3kHz PWM frequency) and 2 bits analog. Depending
on the actual code in the register ‘pwm_code’ the following
algorithm is used:
• If pwm_code bit 7 = 1
Then the upper 6 bits (Bits 7:2) of pwm_code are used for
the 6 bits PWM generation, which controls the selected
currents sinks directly.
• If pwm_code bit 7 =0 and bit 6 = 1
Then bits 6:1 of pwm_code are used for the 6 bits PWM
generation. This signal controls the selected current sinks,
but the analog current of these sinks is divided by 2.
• If pwm_code bit 7 and bit 6 = 0
Then bits 5:0 of pwm_code are used for the 6 bits PWM
generation. This signal controls the selected current sinks,
but the analog current of these sinks is divided by 4.
Figure 59:
PWM Control
0 0
0
6 bit PWM
6 bit PWM
6 bit PWM
to current sink(s) but analog
currents are divided by 4
to current sink(s) but analog
currents are divided by 2
to current sink(s)
7 6 5 4 3 2 1 0
pwm_code
ams Datasheet
[v3-05] 2015-Oct-23
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AS3687/87XM − Detailed Functional Description
Automatic Up/Down Dimming
If the register pwm_dim_mode is set to 01 (up dimming) or 10
(down dimming) the value within the register pwm_code is
increased (up dimming) or decreased (down dimming) every
time and amount (either 1/4 th or 1/8 th) defined by the register
pwm_dim_speed. The maximum value of 255 (completely ON)
and the minimum value of 0 (OFF) is never exceeded. It is used
to smoothly and automatically dim the brightness of the LEDs
connceted to any of the current sinks. The PWM code is readable
all the time (Also during up and down dimming).
The waveform for up dimming looks as follows (cycles omitted
for simplicity):
Figure 60:
PWM Dimming Waveform for Up Dimming (pwm_dim_mode = 01); currX_mode = PWM Controlled
(not all steps shown)
I
currX_current
I/2
I/4
32μs
next step: I/2 with
50% duty cycle
t
I/4 with up to
100% duty cycle
The internal PWM modulator circuit controls the current sinks
as shown in the following figure:
Figure 61:
PWM Control Circuit (currX_mode = 10 (PWM controlled)); X = Any Current Sink
Adder Logic
currX_adder
currX_current
8
/2
0
8
/4
From serial
Interface
pwm_code
2MHz
Dimming
Ramp
Gen
8
PWM
Modulator
subX_en
8
IDAC
CURRX
8
adder_currentX
if pwm_dim_mode = 01 or 10
The adder logic (available for CURR30-32, CURR1, CURR2 and
CURR6) is intended to allow dimming not only from 0% to 100%
(or 100% to 0%) of currX_current, but also e.g. from 10% to 110%
(or 110% to 10%) of currX_current.
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AS3687/87XM − Detailed Functional Description
That means for up dimming the starting current is defined by
0 + currX_adder and the end current is defined by
currX_current + currX_adder.
An overflow of the internal bus (8 Bits wide to the IDAC) has to
be avoided by the register settings (currX_current +
currX_adder must not exceed 255).
If the register subX_en is set, the result from the
pwm_modulator is inverted logically. That means for up
dimming the starting current is defined by currX_adder - 1 and
the end current is defined by currX_adder - currX_current - 1.
An overflow of the internal bus (8 Bits wide to the IDAC) has to
be avoided by the register settings (currX_adder currX_current - 1 must not be below zero).
Its purpose is to dim one channel e.g. CURR30 from e.g. 110%
to 10% of curr30_current and at the same time dim another
channel e.g. CURR31 from 20% to 120% of curr31_current.
Note(s):
• The adder logic operates independent of the currX_mode
setting, but its main purpose is to work together with the
PWM modulator (improved up/down dimming).
• If the adder logic is not used anymore, set the bit
currX_adder to 0. (Setting adder_currentX to 0 is not
sufficient).
Figure 62:
PWM Dimming Table
Decrease by
1/4th Every Step
Decrease by
1/8th Every Step
Seconds
Seconds
Seconds
Seconds
Step
%Dim
ming
PWM
%Dim
ming
PWM
50ms/
Step
25ms/
Step
5ms/
Step
2.5ms/
Step
1
100,0
255
100,0
255
0,00s
0,00s
0,000s
0,000s
2
75,3
192
87,8
224
0,05s
0,03s
0,005s
0,003s
3
56,5
144
76,9
196
0,10s
0,05s
0,010s
0,005s
4
42,4
108
67,5
172
0,15s
0,08s
0,015s
0,008s
5
31,8
81
59,2
151
0,20s
0,10s
0,020s
0,010s
6
23,9
61
52,2
133
0,25s
0,13s
0,025s
0,013s
7
18,0
46
45,9
117
0,30s
0,15s
0,030s
0,015s
8
13,7
35
40,4
103
0,35s
0,18s
0,035s
0,018s
9
10,6
27
35,7
91
0,40s
0,20s
0,040s
0,020s
10
8,2
21
31,4
80
0,45s
0,23s
0,045s
0,023s
11
6,3
16
27,5
70
0,50s
0,25s
0,050s
0,025s
ams Datasheet
[v3-05] 2015-Oct-23
Page 49
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AS3687/87XM − Detailed Functional Description
Decrease by
1/4th Every Step
Decrease by
1/8th Every Step
Seconds
Seconds
Seconds
Seconds
Step
%Dim
ming
PWM
%Dim
ming
PWM
50ms/
Step
25ms/
Step
5ms/
Step
2.5ms/
Step
12
4,7
12
24,3
62
0,55s
0,28s
0,055s
0,028s
13
3,5
9
21,6
55
0,60s
0,30s
0,060s
0,030s
14
2,7
7
19,2
49
0,65s
0,33s
0,065s
0,033s
15
2,4
6
16,9
43
0,70s
0,35s
0,070s
0,035s
16
2,0
5
14,9
38
0,75s
0,38s
0,075s
0,038s
17
1,6
4
13,3
34
0,80s
0,40s
0,080s
0,040s
18
1,2
3
11,8
30
0,85s
0,43s
0,085s
0,043s
19
0,8
2
10,6
27
0,90s
0,45s
0,090s
0,045s
20
0,4
1
9,4
24
0,95s
0,48s
0,095s
0,048s
21
0,0
0
8,2
21
1,00s
0,50s
0,100s
0,050s
22
7,5
19
1,05s
0,53s
0,105s
0,053s
23
6,7
17
1,10s
0,55s
0,110s
0,055s
24
5,9
15
1,15s
0,58s
0,115s
0,058s
25
5,5
14
1,20s
0,60s
0,120s
0,060s
26
5,1
13
1,25s
0,63s
0,125s
0,063s
27
4,7
12
1,30s
0,65s
0,130s
0,065s
28
4,3
11
1,35s
0,68s
0,135s
0,068s
29
3,9
10
1,40s
0,70s
0,140s
0,070s
30
3,5
9
1,45s
0,73s
0,145s
0,073s
31
3,1
8
1,50s
0,75s
0,150s
0,075s
32
2,7
7
1,55s
0,78s
0,155s
0,078s
33
2,4
6
1,60s
0,80s
0,160s
0,080s
34
2,0
5
1,65s
0,83s
0,165s
0,083s
35
1,6
4
1,70s
0,85s
0,170s
0,085s
36
1,2
3
1,75s
0,88s
0,175s
0,088s
37
0,8
2
1,80s
0,90s
0,180s
0,090s
38
0,4
1
1,85s
0,93s
0,185s
0,093s
39
0,0
0
1,90s
0,95s
0,190s
0,095s
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AS3687/87XM − Detailed Functional Description
PWM Generator Registers
Figure 63:
PWM Control Register
PWM Control
Addr: 16h
This register controls PWM generator
Bit
2:1
5:3
Bit Name
pwm_dim_mode
pwm_dim_speed
Default
00
000
Access
Description
R/W
Selects the dimming mode
00 = no dimming; actual content of register pwm_code
is used for PWM generator
01 = logarithmic up dimming (codes are increased).
Start value is actual pwm_code
10 = logarithmic down dimming (codes are decreased)
Start value is actual pwm_code; switch OFF the dimmed
current source after dimming is finished to avoid
unnecessary quiescent current
11 = NA
R/W
Defines dimming speed by increase/decrease
pwm_code …
000 = by 1/4th every 50 ms (total dim time 1.0s)
001 = by 1/8th every 50 ms (total dim time 1.9s)
010 = by 1/4th every 25 ms (total dim time 0.5s)
011 = by 1/8th every 25 ms (total dim time 0.95s)
100 = by 1/4th every 5 ms (total dim time 100ms)
101 = by 1/8th every 5 ms (total dim time 190ms)
110 = by 1/4th every 2.5 ms (total dim time 50ms)
111 = by 1/8th every 2.5 ms (total dim time 95ms)
Figure 64:
PWM Code Register
PWM Code
Addr: 17h
This register controls the PWM code
Bit
7:0
Bit Name
pwm_code
ams Datasheet
[v3-05] 2015-Oct-23
Default
00
Access
R/W
Description
Selects the PWM code
00h = Always 0
...
FFh = Always 1
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AS3687/87XM − Detailed Functional Description
Figure 65:
Adder Current1 Register
Adder Current1
Addr: 30h
Bit
7:0
Bit Name
adder_current1
This register defines the current which can be added to CURR1,
CURR30
Default
00
Access
R/W
Description
Selects the added current value – do not exceed
together with currX_current the internal 8 Bit range
(see text)
00h = 0 (represents 0mA)
...
FFh = 255 (represents 38.25mA)
Figure 66:
Adder Current2 Register
Adder Current2
Addr: 31h
Bit
7:0
Bit Name
adder_current2
This register defines the current which can be added to CURR2,
CURR31
Default
00
Access
R/W
Description
Selects the added current value – do not exceed
together with currX_current the internal 8 Bit range
(see text)
00h = 0 (represents 0mA)
...
FFh = 255 (represents 38.25mA)
Figure 67:
Adder Current3 Register
Adder Current3
Addr: 32h
Bit
7:0
Bit Name
adder_current3
Page 52
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This register defines the current which can be added to CURR6,
CURR32
Default
00
Access
R/W
Description
Selects the added current value – do not exceed
together with currX_current the internal 8 Bit range
(see text)
00h = 0 (represents 0mA)
...
FFh = 255 (represents 38.25mA)
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 68:
Adder Enable2 Register
Adder Enable2
Addr: 34h
Enables the adder circuit for the selected current sources
Bit
0
1
2
3
4
5
Bit Name
curr1_adder
curr2_adder
curr6_adder
curr30_adder
curr31_adder
curr32_adder
ams Datasheet
[v3-05] 2015-Oct-23
Default
0
0
0
0
0
0
Access
Description
R/W
Enables adder circuit for current source CURR1
0 = Normal Operation of the current source
1 = adder_current1 gets added to the current source
current
R/W
Enables adder circuit for current source CURR2
0 = Normal Operation of the current source
1 = adder_current2 gets added to the current source
current
R/W
Enables adder circuit for current source CURR6
0 = Normal Operation of the current source
1 = adder_current3 gets added to the current source
current
R/W
Enables adder circuit for current source CURR30
0 = Normal Operation of the current source
1 = adder_current1 gets added to the current source
current
R/W
Enables adder circuit for current source CURR31
0 = Normal Operation of the current source
1 = adder_current2 gets added to the current source
current
R/W
Enables adder circuit for current source CURR32
0 = Normal Operation of the current source
1 = adder_current3 gets added to the current source
current
Page 53
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AS3687/87XM − Detailed Functional Description
Figure 69:
Subtract Enable Register
Subtract Enable
Addr: 35h
Enable the inversion from the signal from the PWM generator
Bit
0
1
2
Bit Name
sub_en1
sub_en2
sub_en3
Default
Access
Description
R/W
Inverts the signal from the PWM generator
0 = Direct Operation (no inversion)
1 = The signal from the PWM generator for which the adder
is enabled (curr1_adder = 1, curr30_adder = 1) is inverted
R/W
Inverts the signal from the PWM generator
0 = Direct Operation (no inversion)
1 = The signal from the PWM generator for which the adder
is enabled (curr2_adder = 1, curr31_adder = 1) is inverted
R/W
Inverts the signal from the PWM generator
0 = Direct Operation (no inversion)
1 = The signal from the PWM generator for which the adder
is enabled (curr6_adder = 1, curr32_adder = 1) is inverted
0
0
0
LED TEST
Figure 70:
LED Function Testing
Detect Shorted LEDs
From DCDC
Step Up
Converter
D1
C9
4.7μF
R3
1M
I(step_up_vtuning)
DCDC_FB
From Charge
Pump
Baseband
Processor
CPOUT
C8
2.2μF
Interface
ADC
...
Detect Open LEDs
...
Page 54
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
The AS3687/87XM supports the verification of the functionality
of the connected LEDs (open and shorted LEDs can be
detected). This feature is especially useful in production test to
verify the correct assembly of the LEDs, all its connectors and
cables. It can also be used in the field to verify if any of the LEDs
is damaged. A damaged LED can then be disabled (to avoid
unnecessary currents).
The current sources, charge pump, DC/DC converter and the
internal ADC are used to verify the forward voltage of the LEDs.
If this forward voltage is within the specified limits of the LEDs,
the external circuitry is assumed to operate.
Function Testing for single LEDs connected to the
Charge Pump
For any current source connected to the charge pump
(CURR30-33) where only one LED is connected between the
charge pump and the current sink (see Figure 2) use:
Figure 71:
Function Testing for LEDs Connected to the Charge Pump
Step
Action
Example Code
1
Switch ON the charge pump and set it into
manual 1:2 mode (to avoid automatic mode
switching during measurements)
Reg 23h <- 14h (cp_mode = 1:2, manual)
Reg 00h <- 04h (cp_on = 1)
2
Switch ON the current sink for the LED to be
tested
e.g. for register CURR31set to 9mA use
Reg 10h <- 0Fh (curr31_other = 9mA)
Reg 03h <- 0ch (curr31_mode = curr31_other)
3
Measure with the ADC the voltage on CP_OUT
Reg 26h <- 95h (adc_select=CP_OUT,start ADC)
Fetch the ADC result from Reg 27h and 28h
4
Measure with the ADC the voltage on the
switched ON current sink
Reg 26h <- 8bh (adc_select=CURR31,start ADC)
Fetch the ADC result from Reg 27h and 28h
5
Switch OFF the current sink for the LED to be
tested
Reg 03h <- 00h (curr31_mode = OFF)
6
Compare the difference between the ADC
measurements (which is the actual voltage across
the tested LED) against the specification limits of
the tested LED
Calculation performed in baseband μProcessor
7
Do the same procedure for the next LED starting
from point 2
Jump to 2. If not all the LEDs have been tested
8
Switch OFF the charge pump
set charge pump automatic mode
Reg 00h <- 00h (cp_on = 0)
Reg 23h <- 00h
Function Testing for LEDs connected to the Step Up
DC/DC Converter
For LEDs connected to the DC/DC converter (usually current
sinks CURR1,CURR2 and CURR6) use the following procedure:
ams Datasheet
[v3-05] 2015-Oct-23
Page 55
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AS3687/87XM − Detailed Functional Description
Figure 72:
Function Testing for LEDs Connected to the DC/DC Converter
Step
Action
Example Code
1
Switch ON the current sink for the LED string to be
tested (CURR1,2 or 6)
e.g. Test LEDs on CURR1:
Reg 01h <- 01h (curr1_mode=on)
Reg 09h <- 3ch (curr1 = 9mA)
2
Select the feedback path for the LED string to be
tested (e.g. step_up_fb = 01 for LED string on
CURR1)
Reg 21h <- 02h (feedback=curr1)
3
Set the current for step_up_vtuning exactly above
the maximum forward voltage of the tested LED
string + 0.6V (for the current sink) + 0.25V; add 6%
margin (accuracy of step_up_vtuning); this sets
the maximum output voltage limit for the DC/DC
converter
e.g. 4 LEDs with UfMAX = 4.1V gives 17.25V
+6% = 18.29V; if R3=1MΩ and R4 = open, then
select step_up_vtuning = 18 (Reg 21h <- 92h;
results in 19.25V overvoltage protection voltage
– see DC/DC section)
4
Set stepup_prot = 1
Reg 22h <- 04h
5
Switch ON the DC/DC converter
Reg 00h <- 08h
6
Wait 80ms (DCDC_FB settling time)
7
Measure the voltage on DCDC_FB (ADC)
Reg 26h <- 96h (adc_select = DCDC_FB, start
ADC; Fetch the ADC result from Reg 27h and
28h)
8
If the voltage on DCDC_FB is above 1.0V, the
tested LED string is broken – then skip the
following steps
(Code >199h)
9
Switch OFF the overvoltage protection
(stepup_prot = 0)
Reg 22h <- 00h
10
Reduce step_up_vtuning step by step until the
measured voltage on DCDC_FB (ADC) is above
1.0V. After changing step_up_vtuning always wait
80ms, before AD-conversion
e.g.: Reg 21h <- 62h (step_up_vtuning=12): ADC
result=1,602V
11
Measure voltage on DCDC_FB
e.g. DCDC_FB=1.602V
12
Switch OFF the DC/DC converter
Reg 00h <- 00h
13
The voltage on the LED string can be calculated
now as follows (R4 = open): VLEDSTRING =
V(DCDC_FB) + I(step_up_vtuning) * R3 – 0.5V
(current sinks feedback voltage: VFB2).
V(DCDC_FB) = ADC Measurement from point 11
I(step_up_vtuing) = last setting used for point 10
e.g.: VLED = (1.602V + 12V – 0.5V) / 4 = 3.276V
14
Compare the calculated value against the
specification limits of the tested LEDs
With the above described procedures electrically open and
shorted LEDs can be automatically detected.
Page 56
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Analog-To-Digital Converter
The AS3687/87XM has a built-in 10-bit successive
approximation analog-to-digital converter (ADC). It is internally
supplied by V2_5, which is also the full-scale input range (0V
defines the ADC zero-code). For input signal exceeding V2_5
(typ. 2.5V) a resistor divider with a gain of 0.4 (Ratio prescaler) is
used to scale the input of the ADC converter. Consequently the
resolution is:
Figure 73:
ADC Input Ranges, Compliances and Resolution
Input Range
VLSB
0V-2.5V
2.44mV
ADCTEMP_CODE
-30°C to 125°C
1 / ADC TC
CURR30-33
VBAT, CP_OUT
0V-5.5V
6.1mV
VLSB=2.5/1024 * 1/0.4;
internal resistor divider used
CURR1, CURR2, CURR6
0V-1.0V
2.44mV
VLSB=2.5/1024
Channels (Pins)
DCDC_FB
Note
VLSB=2.5/1024
Junction temperature
Figure 74:
ADC Parameters
Symbol
Parameter
Min
Typ
Max
Unit
Resolution
10
Vin
Input Voltage Range
VSS
DNL
Differential
Non-Linearity
± 0.25
LSB
INL
Integral Non-Linearity
± 0.5
LSB
Vos
Input Offset Voltage
± 0.25
LSB
Rin
Input Impedance
Cin
Input Capacitance
Note
Bit
Vsupply
100
V
Vsupply = V2_5
MΩ
9
pF
Vsupply
(V2_5)
Power Supply Range
2.5
V
±2%, internally trimmed.
Idd
Power Supply Current
500
μA
During conversion only.
Idd
Power Down Current
100
nA
T TOL
Temperature Sensor
Accuracy
ams Datasheet
[v3-05] 2015-Oct-23
-10
+10
°C
@ 25 °C
Page 57
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AS3687/87XM − Detailed Functional Description
Symbol
ADCTOFFSET
Parameter
Min
Typ
ADC temperature
measurement offset
value
Max
Unit
375
°C
°C/
Code
ADCTC
Code temperature
coefficient
1.2939
Ratioprescaler
Ratio of Prescaler
0.4
Note
Temperature change per
ADC LSB
For all low voltage current
sinks, CP_OUT and VBAT
Transient Parameters (2.5V, 25 °C)
Tc
Conversion Time
27
μs
fc
Clock Frequency
1.0
MHz
ts
Settling Time of S&H
16
μs
All signals are internally
generated and triggered
by start_conversion
The junction temperature (TJUNCTION) can be calculated with
the following formula (ADC TEMP_CODE is the ADC conversion
result for channel 17h selected by register
adc_select = 010111):
(EQ5)
TJUNCTION [ºC] = ADC TOFFSET – ADC TC . ADC TEMP_CODE
Application Hint: Extending the ADC Input Voltage
Range for CURR1,2,6
Under certain operating conditions, the input voltage range for
the ADC input CURR1,2,6 (specified from 0.0V- 1.0V for all
operating conditions in table “ADC Input Ranges, Compliances
and Resolution”) can be extended as follows:
Figure 75:
Internal Voltage of the ADC vs. Applied Voltage on CURR1,2 or CURR6
2.5
2.0
VADC (CP=on)
VPIN (V)
1.5
VADC (CP=off )
1.0
0.5
0.0
0.0
0.5
1.0
1.5
2.0
2.5
DC (V)
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Operating Conditions: VBAT ≥ 3.3V, TJUNC ≥ -20°C (one curve
with charge pump operating in 1:2 mode ‘ON’ and one curve
with charge pump in 1:1 mode ‘OFF’).
Above curve represent the worst case and therefore are
guaranteed by design under the above operating conditions
(ADC input range for CURR1,2,6 is between 0V and 1.5V).
ADC Registers
Figure 76:
ADC_MSB Result Register
ADC_MSB Result
Addr:27h
Together with Register 27h, this register contains the results
(MSB) of an ADC cycle
Bit
Bit Name
Default
Access
Description
6:0
D9:D3
N/A
R
ADC results register.
7
result_not_ready
N/A
R
Indicates end of ADC conversion cycle.
0 = Result is ready.
1 = Conversion is running.
Figure 77:
ADC_LSB Result Register
ADC_LSB Result
Addr:28h
Together with Register 28h, this register contains the results
(LSB) of an ADC cycle
Bit
Bit Name
Default
Access
2:0
D2:D0
N/A
R
ams Datasheet
[v3-05] 2015-Oct-23
Description
ADC results register.
Page 59
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AS3687/87XM − Detailed Functional Description
Figure 78:
ADC_Control Register
Adc_Control
Addr:26h
This register input source selection and initialization of ADC
Bit
5:0
Bit Name
adc_select (1)
Default
0
Access
Description
R/W
Selects input source as ADC input.
000000 (00h) = reserved
000001 (01h) = reserved
000010 (02h) = reserved
000011 (03h) = reserved
000100 (04h) = reserved
000101 (05h) = reserved
000110 (06h) = reserved
000111 (07h) = reserved
001000 (08h) = CURR1
001001 (09h) = CURR2
001010 (0Ah) = CURR30
001011 (0Bh) = CURR31
001100 (0Ch) = CURR32
001101 (0Dh) = CURR33
001110 (0Eh) = reserved
001111 (0Fh) = reserved
010000 (10h) = reserved
010001 (11h) = reserved
010010 (12h) = reserved
010011 (13h) = CURR6
010100 (14h) = VBAT
010101 (15h) = CP_OUT
010110 (16h) = DCDC_FB
010111 (17h) = ADCTEMP_CODE (junction temperature)
011xxx, 1xxxxx = reserved
6
7
Reserved – don’t use; always write 0 to this register
start_conversion
N/A
W
Writing a 1 into this bit starts one ADC conversion cycle.
Note(s) and/or Footnote(s):
1. See ADC Input Ranges, Compliances and Resolution, for ADC ranges and possible.
Page 60
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 79:
ADC Circuit
V2_5
CURR1
CURR2
CURR6
DCDC_FB
10bit SAR
ADC
vtemp
CURR30
CURR31
CURR32
CURR33
VBAT
VCP
D9:D0
result_not_ready
1MHz
nc
180k
Control
120k
adc_select
start_conversion
Audio Controlled RGB LEDs (only AS3687XM)
Up to 2 RGB LEDs (connected to the pins CURR30-CURR32
and/or CURR1,2,6) can be controlled by an audio source
(connected to pin CURR33/AUDIO_IN). The color of the RGB
LED(s) is depending on the input amplitude and it starts from
black transitions to blue, green, cyan, yellow, red and for high
amplitudes white is used (internal lookup table if
audio_color=000).
Figure 80:
Audio Controlled RGB LED Application Circuit
AS3687XM
CPOUT
Current Sinks
each 0.15-38.25mA
DRGB1
C5
1.0μF
CURR30
CURR31
CURR32
CURR33/AUDIO_IN
C10
100nF
Audio IN
Alternative:
2nd Audio or Backlight
Audio Processing
HV Current Sinks
each 0.15-38.25mA
DRGB2
D2
D3
D4
CURR1
CURR2
CURR6
ams Datasheet
[v3-05] 2015-Oct-23
Page 61
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AS3687/87XM − Detailed Functional Description
The internal circuit has the following functions:
Figure 81:
Audio Controlled RGB LED Internal Circuit
audio_gain
-12dB...+30dB
CURR33/AUDIO_IN
optional
Audio IN
ADC
1.25V
aud_buf_on adc_select
rgb_amplitude
Level
Detect /
Fadeout
AGC
Look
Up
Table
audio_speed
agc_ctrl
audio_color
DC
Remove
CURR30
other modes
CURR31
other modes
CURR32
other modes
curr3x_out
CURR1
other modes
CURR2
other modes
CURR6
other modes
curr126_out
The audio controlled LED block is enabled if any of the registers
curr3x_out or curr126_out is not zero. The audio input amplifier
(enabled by aud_buf_on=1) is used to allow the attenuation (or
amplification of the input signal) and has the following
parameters:
Figure 82:
Audio Input Parameters
Symbol
Vin
Rin_min
Parameter
Input Voltage Range
Min. Input Impedance
Page 62
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Min
Typ
0
20
Max
Unit
2.5
V
kΩ
Note
At max. input gain (30dB)
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
When audio control RGB LED is active, the internal ADC is
continuously running at a sample frequency of 45.5kHz. In this
case the ADC cannot be used for any other purpose.
The input amplitude is mapped into different colors for RGB
LED(s) or brightness for single color LED(s). The mapping is
controlled by the register audio_color. If audio_color = 000,
then the mapping is done as follows: Very low amplitudes are
mapped to black, for higher amplitudes, the color smoothly
transitions from blue, green, cyan, yellow, red and eventually
to white (for high input amplitudes). Otherwise the output is
mapped to the brightness of a single color.
AGC
The AGC is used to ‘compress’ the input signal and to attenuate
very low input amplitude signals (this is performed to ensure
no light output for low signals especially for noisy input signals).
The AGC monitors the input signal amplitude and filters this
amplitude with a filter with a short attack time, but a long decay
time (decay time depends on the register agc_ctrl). This
amplitude measurement (represented by an integer value from
0 to 15) is then used to amplify or attenuate the input signal
with one of the following amplification ratios (output to input
ratio) – the curve A, B, or C is selected depending on the register
agc_ctrl:
Figure 83:
AGC Curve A
X-Axis: Input Amplitude; Y-Axis: Output Amplitude; Actual Value: Gain Between Output to Input
ams Datasheet
[v3-05] 2015-Oct-23
Page 63
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AS3687/87XM − Detailed Functional Description
Figure 84:
AGC Curve B
X-Axis: Input Amplitude, Y-Axis: Output Amplitude; Actual Value: Gain Between Output to Input
Figure 85:
AGC Curve C
X-Axis: Input Amplitude, Y-Axis: Output Amplitude; Actual Value: Gain Between Output to Input
Page 64
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Audio Control Registers
Figure 86:
Audio Control Register (only AS3687XM)
Audio Control (only AS3687XM)
Addr:46h
Audio controlled LED mode control
Bit
Bit Name
Default
Access
0
aud_buf_on
0
R/W
Audio input buffer enable
0 = OFF
1 = ON
R/W
Audio controlled LED color selection
000 = Color scheme defined by lookup table
001-111 = Fixed color scheme (b2=R, b1=G, b0=B) –
single color only (e.g. Red: 100)
R/W
Audio controlled LED persistence time
00 = None
01 = 200ms
10 = 400ms
11 = 800ms
4:2
7:6
audio_color
audio_speed
ams Datasheet
[v3-05] 2015-Oct-23
000
00
Description
Page 65
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AS3687/87XM − Detailed Functional Description
Figure 87:
Audio Input Register (only AS3687XM)
Audio Input (only AS3687XM)
Addr:47h
Audio controlled LED input control
Bit
2:0
5:3
Bit Name
audio_gain
agc_ctrl
Default
000
000
Access
Description
R/W
Audio input buffer gain control
000 = -12dB
001 = -6dB
010 = 0dB
011 = +6dB
100 = +12dB
101 = +18dB
110 = +24dB
111 = +30dB
R/W
Audio input buffer AGC function controls AGC transfer
function
000 = AGC OFF
001 attenuate low amplitude signals otherwise linear
response (to remove e.g. noise)
010 = AGC curve A; slow decay of amplitude detection
011 = AGC curve A; fast decay of amplitude detection
100 = AGC curve B; slow decay of amplitude detection
101 = AGC curve B; fast decay of amplitude detection
110 = AGC curve C; slow decay of amplitude detection
111 = AGC curve C; fast decay of amplitude detection
6
audio_man_start
0
R/W
Startup Control of audio input buffer (for charging of
external AC-coupling capacitor)
0 = Automatic precharging 300μs
(if audio_dis_start = 0)
1 = Continuously precharging (if audio_buf_on = 1)
7
audio_dis_start
0
R/W
Disable Startup Control of audio input buffer
0 = Precharging enabled
1 = Precharging disabled
Page 66
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 88:
Audio Output Register (only AS3687XM)
Audio Output (only AS3687XM)
Addr:48h
Audio controlled LED output control
Bit
Bit Name
Default
Access
Description
2:0
rgb_amplitude
000
R/W
RGB output amplitude control (in % of selected output
current) – master amplitude control
000 = 6.25%
001 = 12.5%
010 = 25%
011 = 50%
100 = 75%
101 = 87.5%
110 = 93.75%
111 = 100%
3
curr3x_out
0
R/W
Audio sync enable for CURR30-CURR32
0 = OFF
1 = ON, ADC continuously running with f=500kHz
4
curr126_out
0
R/W
Audio sync enable for CURR1, CURR2, CURR6
0 = OFF
1 = ON, ADC continuously running with f=500kHz
ams Datasheet
[v3-05] 2015-Oct-23
Page 67
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AS3687/87XM − Detailed Functional Description
Power ON Reset
The internal reset is controlled by two sources:
• VBAT Supply
• Serial interface state (SCL, SDA)
The internal reset is forced if VBAT is low or if both interface pins
(SCL, SDA) are low for more than 100ms. The device enters
shutdown mode, when SCL and SDA remain low.
The reset levels control the state of all registers. As long as VBAT
and SCL/SDA are below their reset thresholds, the register
contents are set to default. Access by serial interface is possible
once the reset thresholds are exceeded.
Figure 89:
Zero Power Device Wakeup Block Diagram
power-on to internal
references and V2_5 LDO
VBAT
Zero Power
Device Wakeup
VBAT
shutdn_disab
on
VBAT
VDD_I/F
R4
1-10k
DATA
fast_shutdwn
R5
V2_5
V2_5
DATA
Serial
Interface
Logic
V2_5
CLK
debounce
timer
1ms/100ms
CLK
VBAT
Page 68
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 90:
Reset Levels
Symbol
Parameter
Min
Typ
Max
Unit
Note
Overall Power-On
Reset
1.8
2.15
2.4
V
Monitor voltage on V2_5;
power ON reset for all
internal functions. (1)
VPOR_PERI
Reset Level for pins
SCL, SDA
0.29
1.0
1.38
V
Monitor voltage on pins
SCL, SDA
tPOR_DEB
Reset debounce time
for pins SCL, SDA
80
100
120
ms
tSTART
Interface Startup Time
4
6
8
ms
VPOR_VBAT
Note(s) and/or Footnote(s):
1. Guaranteed by design – not production tested.
ams Datasheet
[v3-05] 2015-Oct-23
Page 69
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AS3687/87XM − Detailed Functional Description
Reset Control Register
Figure 91:
Overtemp Control Register
Overtemp Control
Addr:29h
This register reads and resets the overtemperature flag
Bit
4
Bit Name
Default
shutdwn_enab
0
Access
R/W
Description
Enable Shutdown mode and serial interface reset.
0 = Serial Interface reset disabled. Device does not
enter
Shutdown mode
1 = Serial Interface reset enabled, device enters
shutdown
when SCL and SDA remain low for min. 120ms
Temperature Supervision
An integrated temperature sensor provides overtemperature
protection for the AS3687/87XM. This sensor generates a flag if
the device temperature reaches the overtemperature threshold
of 140°. The threshold has a hysteresis to prevent oscillation
effects.
If the device temperature exceeds the 140° threshold all current
sources, the charge pump and the DC/DC converter is disabled
and the ov_temp flag is set. After decreasing the temperature
by 5° (typically) operation is resumed.
The ov_temp flag can only be reset by first writing a 1 and then
a 0 to the bit rst_ov_temp.
Bit ov_temp_on = 1 activates temperature supervision.
Figure 92:
Overtemp Detection
Symbol
Parameter
T140
ov_temp Rising Threshold
Thyst
ov_temp Hystersis
Page 70
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Min
Typ
Max
Unit
140
°C
5
°C
Note
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Temperature Supervision Registers
Figure 93:
Overtemperature Control Register
Overtemp Control
Addr:29h
This register reads and resets the overtemperature flag
Bit
Bit Name
Default
Access
Description
0
ov_temp_on
1
W
Activates/deactivates device temperature supervision.
Default: OFF - all other bits are only valid if this bit is set to 1.
0 = Temperature supervision is disabled. No reset will be
generated if the device temperature exceeds 140°C.
1 = Temperature supervision is enabled.
1
ov_temp
N/A
R
1 = Indicates that the overtemperature threshold has been
reached; this flag is not cleared by an overtemperature reset.
It has to be cleared using bit rst_ov_temp.
2
rst_ov_temp
0
R/W
The ov_temp flag is cleared by first setting this bit to 1, and
then setting this bit to 0.
Serial Interface
The AS3687/87XM is controlled using serial interface pins CLK
and DATA:
Figure 94:
Serial Interface Block Diagram
VDD_I/F
R4
1-10k
DATA
CLK
R5
DATA
CLK
Serial
Interface
Logic
The clock line CLK is never held low by the AS3687/87XM (as
the AS3687/87XM does not use clock stretching of the bus).
ams Datasheet
[v3-05] 2015-Oct-23
Page 71
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AS3687/87XM − Detailed Functional Description
Figure 95:
Serial Interface Timing
Symbol
Parameter
Min
VIHI/F
High Level Input voltage
VILI/F
Low Level Input voltage
VHYSTI/F
Max
Unit
1.38
VBAT
V
0.0
0.52
V
Hysteresis
Typ
0.1
V
tRISE
Rise Time - VILI/F to VIHI/F
0
1000
ns
tFALL
Fall Time - VIHI/F to VILI/F
0
300
ns
tCLK_FILTER
Spike Filter on CLK
100
ns
tDATA_FILTER
Spike Filter on DATA
300
ns
Note
Pins DATA and CLK
Serial Interface Features
• Fast Mode Capability (Maximum Clock Frequency is
400 kHz)
• 7-bit Addressing Mode
• Write Formats
• Single-Byte Write
• Page-Write
• Read Formats
• Current-Address Read
• Random-Read
• Sequential-Read
• DATA Input Delay and CLK Spike Filtering by Integrated RC
Components
Device Address Selection
The serial interface address of the AS3687/87XM has the
following address:
• 80h – Write Commands
• 81h – Read Commands
Page 72
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
Figure 96:
Complete Serial Data Transfer
DATA
CLK
S
Start
Condition
1-7
8
Address
R/W
9
8
1-7
ACK
Data
9
ACK
1-7
Data
8
9
P
ACK
Stop
Condition
Serial Data Transfer Formats
Definitions used in the serial data transfer format diagrams are
listed in the following table:
Figure 97:
Serial Data Transfer Byte Definitions
Symbol
Definition
R/W
(AS3687/87XM Slave)
Notes
S
Start Condition after Stop
R
1 bit
Sr
Repeated Start
R
1 bit
DW
Device Address for Write
R
10000000 (80h).
DR
Device Address for Read
R
10000001 (81h)
WA
Word Address
R
8 bits
A
Acknowledge
W
1 bit
N
Not Acknowledge
R
1 bit
reg_data
Register Data/Write
R
8 bits
data (n)
Register Data/read
R
1 bit
Stop Condition
R
8 bits
Increment Word Address Internally
R
During Acknowledge
P
WA++
ams Datasheet
[v3-05] 2015-Oct-23
Page 73
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AS3687/87XM − Detailed Functional Description
Figure 98:
Serial Interface Byte Write
S
DW
A
WA
A
reg_data
A P
Write Register
WA++
AS3687/87XM
AS3687/87XM
(= Slave) receives data
(= Slave) transmits data
Figure 99:
Serial Interface Page Write
S
DW
A
WA
A
reg_data 1
A
reg_data 2
Write Register
WA++
AS3687/87XM
AS3687/87XM
A
…
Write Register
WA++
reg_data n
A P
Write Register
WA++
(= Slave) receives data
(= Slave) transmits data
Byte Write and Page Write formats are used to write data to the
slave.
The transmission begins with the START condition, which is
generated by the master when the bus is in IDLE state (the bus
is free). The device-write address is followed by the word
address. After the word address any number of data bytes can
be sent to the slave. The word address is incremented internally,
in order to write subsequent data bytes on subsequent address
locations. For reading data from the slave device, the master
has to change the transfer direction. This can be done either
with a repeated START condition followed by the device-read
address, or simply with a new transmission START followed by
the device-read address, when the bus is in IDLE state. The
device-read address is always followed by the 1st register byte
transmitted from the slave. In Read Mode any number of
subsequent register bytes can be read from the slave. The word
address is incremented internally.
Page 74
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Detailed Functional Description
The following diagrams show the serial read formats supported
by the AS3687/87XM.
Figure 100:
Serial Interface Random Read
S
DW
A
WA
A Sr
DR
A
data
N P
Read Register
WA++
AS3687/87XM
AS3687/87XM
(= Slave) receives data
(= Slave) transmits data
Random Read and Sequential Read are combined formats. The
repeated START condition is used to change the direction after
the data transfer from the master.
The word address transfer is initiated with a START condition
issued by the master while the bus is idle. The START condition
is followed by the device-write address and the word address.
In order to change the data direction a repeated START
condition is issued on the 1st CLK pulse after the
ACKNOWLEDGE bit of the word address transfer. After the
reception of the device-read address, the slave becomes the
transmitter. In this state the slave transmits register data
located by the previous received word address vector. The
master responds to the data byte with a NOT ACKNOWLEDGE,
and issues a STOP condition on the bus.
Figure 101:
Serial Interface Sequential Read
S
DW
A
WA
A Sr
DR
A
data 1
A
data 2
...
A
data n
N P
Read Register
WA++
AS3687/87XM
AS3687/87XM
(= Slave) receives data
(= Slave) transmits data
Sequential Read is the extended form of Random Read, as
multiple register-data bytes are subsequently transferred.
In contrast to the Random Read, in a sequential read the
transferred register-data bytes are responded by an
acknowledge from the master. The number of data bytes
transferred in one sequence is unlimited (consider the behavior
of the word-address counter). To terminate the transmission the
master has to send a NOT ACKNOWLEDGE following the last
data byte and subsequently generate the STOP condition.
ams Datasheet
[v3-05] 2015-Oct-23
Page 75
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AS3687/87XM − Detailed Functional Description
Figure 102:
Serial Interface Current Address Read
S
DR
A
data 1
Read Register
WA++
A
data 2
…
Read Register
WA++
A
data n
N P
Read Register
WA++
AS3687 (= slave) receives data
AS3687 (= slave) transmits data
To keep the access time as small as possible, this format allows
a read access without the word address transfer in advance to
the data transfer. The bus is idle and the master issues a START
condition followed by the Device- Read address.
Analogous to Random Read, a single byte transfer is terminated
with a NOT ACKNOWLEDGE after the 1st register byte.
Analogous to Sequential Read an unlimited number of data
bytes can be transferred, where the data bytes must be
responded to with an ACKNOWLEDGE from the master.
For termination of the transmission the master sends a NOT
ACKNOWLEDGE following the last data byte and a subsequent
STOP condition.
Operating Modes
If the voltage on SCL and SDA is less than 1V (for > t POR_DEB ),
the AS3687/87XM is in shutdown mode and its current
consumption is minimized (I BAT = I SHUTDOWN) and all internal
registers are reset to their default values.
If the voltage at SCL or SDA rises above 1V, the AS3687/87XM
serial interface is enabled and the AS3687/87XM and the
standby mode is selected. The AS3687/87XM is switched
automatically from standby mode (I(BAT) = I STANDBY ) into
normal mode (I(BAT) = I ACTIVE) and back, if one of the following
blocks are activated:
• Charge pump
• Step up regulator
• Any current sink
• ADC conversion started
• PWM active
• Pattern mode active.
If any of these blocks are already switched ON the internal
oscillator is running and a write instruction to the registers is
directly evaluated within 1 internal CLK Cycle (typ. 1μs).
If all these blocks are disabled, a write instruction to enable
these blocks is delayed by 64 CLK cycles (oscillator will startup,
within max 200μs).
Page 76
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ams Datasheet
[v3-05] 2015-Oct-23
A S 3 6 8 7 / 8 7 X M − Detailed Functional Description
Register Map
Figure 103:
Register Map
Register Definition
Content
Addr.
Default
Name
b7
b6
b5
b4
b3
b2
step_up_
on
cp_on
Reg. Control
00h
00
Curr12 Control
01h
00h
Curr Rgb Control
02h
00h
curr6_mode
Curr3 Control1
03h
00h
curr33_mode
Curr1 Current
09h
00h
curr1_current
Curr2 Current
0Ah
00h
curr2_current
Curr3x Strobe
0Eh
00h
curr3x_strobe
Curr3x Preview
0Fh
00h
curr3x_preview
Curr3x Other
10h
00h
curr3x_other
Curr3 Strobe Control
11h
00h
Curr3 Control2
12h
00h
PWM Control
16h
00h
PWM Code
17h
00h
Pattern Control
18h
00h
ams Datasheet
[v3-05] 2015-Oct-23
curr32_mode
strobe_timing
b1
b0
curr2_mode
curr1_mode
curr31_mode
curr30_mode
strobe_mode
curr3x_
strobe_ high
strobe_ctrl
preview_ctrl
pwm_dim_speed
preview_off_
aft er strobe
pwm_dim_mode
pwm_code
curr33_
pattern
curr32_
pattern
curr31_
pattern
curr30_
pattern
softdim_
pattern
pattern_delay
pattern_
color
Page 77
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A S 3 6 8 7 / 8 7 X M − Detailed Functional Description
Register Definition
Content
Addr.
Default
Name
b7
b6
b5
b4
b3
Pattern Data0
19h
00h
pattern_data[7:0]
Pattern Data1
1Ah
00h
pattern_data[15:8]
Pattern Data2
1Bh
00h
pattern_data[23:16]
Pattern Data3
1Ch
00h
pattern_data[31:24]
DC/DC Control1
21h
00h
DC/DC Control2
22h
04h
CP Control
23h
00h
CP Mode Switch1
24h
00h
CP Mode Switch2
25h
00h
curr6_
on_cp
ADC_Control
26h
00h
start_conv
ersion
adc_on
ADC_MSB Result
27h
NA
result_
not_ready
D9
ADC_LSB Result
28h
NA
Overtemp Control
29h
01h
Page 78
Document Feedback
b2
step_up_vtuning
step_up
_fb_auto
curr6_
prot_on
curr2_
prot_on
cp_auto_
on
cp_start
_debou nce
b1
b0
step_up_
frequ
step_up_fb
curr1_
prot_on
step_up_
lowcur
step_up_
prot
cp_mode_switching
curr33_
on_cp
skip_fast
cp_mode
curr32_
on_cp
step_up_res
cp_clk
curr31_
on_cp
curr30_
on_cp
curr2_
on_cp
curr2_on_cp
D5
D4
D3
D2
D1
D0
rst_ov_
temp
ov_temp
ov_temp
adc_select
D8
D7
shutdwn_
enab
D6
ams Datasheet
[v3-05] 2015-Oct-23
A S 3 6 8 7 / 8 7 X M − Detailed Functional Description
Register Definition
Content
Addr.
Default
Name
b7
b6
b5
b4
curr6_
lo w_v
b3
b2
b1
b0
curr33_
low_v
curr32_
low_v
curr31_
low_v
curr30_
low_v
curr2_
low_v
curr1_low_v
curr6_
adder
curr2_
adder
curr1_adder
sub_en3
sub_en2
sub_en1
0
1
0
Curr Low Voltage Status1
2Ah
NA
Curr Low Voltage Status2
2Bh
NA
GPIO Current
2Ch
00h
Curr6 Current
2Fh
00h
curr6_current
Adder Current1
30h
00h
adder_current1 (can be enabled for CURR30, CURR1)
Adder Current2
31h
00h
adder_current2 (can be enabled for CURR31, CURR2)
Adder Current3
32h
00h
adder_current3 (can be enabled for CURR32, CURR6)
Adder Enable2
34h
00h
curr32_
adder
Subtract Enable
35h
00h
ASIC ID1
3Eh
CAh
1
1
0
0
ASIC ID2
3Fh
50h
0
1
0
1
Curr30 Current
40h
00h
curr30_current
Curr31 Current
41h
00h
curr31_current
Curr32 Current
42h
00h
curr32_current
Curr33 Current
43h
00h
curr33_current
ams Datasheet
[v3-05] 2015-Oct-23
pattern_
slow
pattern_
delay2
curr31_
adder
curr30_
adder
1
revision
Page 79
Document Feedback
A S 3 6 8 7 / 8 7 X M − Detailed Functional Description
Register Definition
Content
Addr.
Default
Name
b7
Audio Control
(Only AS3687XM)
46h
00h
Audio Input
(Only AS3687XM)
47h
00h
Audio Output
(Only AS3687XM)
48h
00h
b6
b5
b4
audio_speed
audio_
dis_start
audio_
man_
st art
b3
b2
b1
b0
audio_color
agc_ctrl
curr126 _out
aud_buf _on
audio_gain
curr3x_
out
rgb_amplitude
Note(s) and/or Footnote(s):
1. If writing to register, write 0 to unused bits.
2. Write to read only bits will be ignored.
3. Grey color = read only.
Page 80
Document Feedback
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − External Components
External Components
Figure 104:
External Components List
Part
Number
Min
Value
Typ
Max
Tol
(Min)
Rating
(Max)
Notes
Package
(Min)
C1
1μF
±20%
6.3V
Ceramic, X5R (V2_5 output)
(e.g. Taiyo Yuden
JMK105BJ105KV-F)
0402
C2
1μF
±20%
6.3V
Ceramic, X5R (VBAT) (e.g.
Taiyo Yuden
JMK107BJ225MA-T)
0402
C3
500nF
±20%
6.3V
Ceramic, X5R (Charge
Pump) (e.g. Taiyo Yuden
JMK107BJ225MA-T)
0402
C4
500nF
±20%
6.3V
Ceramic, X5R (Charge
Pump) (e.g. Taiyo Yuden
JMK107BJ225MA-T)
0402
C5
1μF
±20%
6.3V
Ceramic, X5R (Charge
Pump Output) (e.g. Taiyo
Yuden JMK107BJ225MA-T)
0403
C6
1μF
±20%
6.3V
Ceramic, X5R (Step Up
DC/DC input) (e.g. Taiyo
Yuden JMK107BJ225MA-T)
0402
C7
1.5nF
±20%
25V
Ceramic, X5R (Step Up
DC/DC Feedback, 150pF for
overvoltage protection)
0402
C8
15nF
±20%
6.3V
Ceramic, X5R (Step Up
DC/DC Feedback, 1.5nF for
overvoltage protection)
0402
C9
4.7μF
±20%
25V
Ceramic, X5R, X7R (Step Up
DC/DC output) (e.g. Taiyo
Yuden TMK316BJ475KG)
1206
(0805)
C10
100nF
±20%
6.3V
Ceramic, X5R, X7R (Audio
DC Block capacitor) – only
for AS3687XM
0402
R1
100mΩ
±5%
Shunt Resistor
0603
R2
1MΩ
±1%
Step Up DC/DC Converter
Voltage Feedback
0201
±1%
Step Up DC/DC Converter
Voltage Feedback - not
required for overvoltage
protection
0201
R3
ams Datasheet
[v3-05] 2015-Oct-23
100kΩ
Page 81
Document Feedback
AS3687/87XM − External Components
Part
Number
Min
R4
Value
Typ
1-10kΩ
Max
Tol
(Min)
±1%
R5
L1
10μH
Q1 (+ D1)
FDFMA3N109
D2:D14
LED
Page 82
Document Feedback
±20%
Rating
(Max)
Notes
Package
(Min)
I²C Bus DATA Pullup resistor
– usually already inside I²C
master
0201
I²C Bus CLK Pullup resistor –
usually already inside I²C
master
0201
Panasonic ELLSFG100MA
or TDK VLF3012A or
LQH3NPN100NJ0
Integrated NMOS and
Schottky diode
MicroFET
2×2mm
As required by application
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Package Drawings & Markings
Package Drawings & Markings
Figure 105:
WL-CSP 4×5 Balls Package Drawing
Marking:
ams Datasheet
[v3-05] 2015-Oct-23
Line 1:
ams Logo
Line 2:
AS36
Line 3:
87
87XM
Line 4:
<Code>
4 Letter Tracecode
(for AS3687)
(for AS3687XM)
Page 83
Document Feedback
AS3687/87XM − Package Drawings & Markings
Figure 106:
WL-CSP 4×5 Balls Detail Dimensions
Bottom View (Ball Side)
282.5
μm
500μm
500μm
500μm
Side View
350
+/-10
μm
282.5
μm
250
+/-20
μm
272.5
μm
Top View (through)
Pin A1
Indicator
A2
A3
A4
A4
A3
A2
A1
B1
B2
B3
B4
B4
B3
B2
B1
C1
C2
C3
C4
C4
C3
C2
C1
D1
D2
D3
D4
D4
D3
D2
D1
E1
E2
E3
E4
E4
E3
E2
E1
2065 +/-20μm
The coplanarity of the balls is 40μm.
Page 84
Document Feedback
500μm
272.5
μm
500μm
500μm
+/ Ø3
- 1 11
0μ
m
2545 +/-20μm
2545 +/-20μm
500μm
A1
600 +/-30μm
2065 +/-20μm
RoHS
Green
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Ordering & Contact Information
Ordering & Contact Information
Figure 107:
Ordering Information
Part Number
Description
AS3687-ZWLT (1)
Lighting Management
Unit
AS3687XM-ZWLT
Lighting Management
Unit (including audio
controlled light)
Marking
Package
Delivery
Form
Delivery
Quantity
AS3687
WL-CSP
4×5 balls
Tape & Reel
6500
WL-CSP
4×5 balls
Tape & Reel
6500
AS3687XM
Note(s) and/or Footnote(s):
1. Do not use AS3687 for new designs – use AS3687XM (drop in pin to pin compatible replacement for AS3687) instead.
Buy our products or get free samples online at:
www.ams.com/ICdirect
Technical Support is available at:
www.ams.com/Technical-Support
Provide feedback about this document at:
www.ams.com/Document-Feedback
For further information and requests, e-mail us at:
[email protected]
For sales offices, distributors and representatives, please visit:
www.ams.com/contact
Headquarters
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten
Austria, Europe
Tel: +43 (0) 3136 500 0
Website: www.ams.com
ams Datasheet
[v3-05] 2015-Oct-23
Page 85
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AS3687/87XM − RoHS Compliant & ams Green Statement
RoHS Compliant & ams Green
Statement
RoHS: The term RoHS compliant means that ams AG products
fully comply with current RoHS directives. Our semiconductor
products do not contain any chemicals for all 6 substance
categories, including the requirement that lead not exceed
0.1% by weight in homogeneous materials. Where designed to
be soldered at high temperatures, RoHS compliant products are
suitable for use in specified lead-free processes.
ams Green (RoHS compliant and no Sb/Br): ams Green
defines that in addition to RoHS compliance, our products are
free of Bromine (Br) and Antimony (Sb) based flame retardants
(Br or Sb do not exceed 0.1% by weight in homogeneous
material).
Important Information: The information provided in this
statement represents ams AG knowledge and belief as of the
date that it is provided. ams AG bases its knowledge and belief
on information provided by third parties, and makes no
representation or warranty as to the accuracy of such
information. Efforts are underway to better integrate
information from third parties. ams AG has taken and continues
to take reasonable steps to provide representative and accurate
information but may not have conducted destructive testing or
chemical analysis on incoming materials and chemicals. ams AG
and ams AG suppliers consider certain information to be
proprietary, and thus CAS numbers and other limited
information may not be available for release.
Page 86
Document Feedback
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Copyrights & Disclaimer
Copyrights & Disclaimer
Copyright ams AG, Tobelbader Strasse 30, 8141
Unterpremstaetten, Austria-Europe. Trademarks Registered. All
rights reserved. The material herein may not be reproduced,
adapted, merged, translated, stored, or used without the prior
written consent of the copyright owner.
Devices sold by ams AG are covered by the warranty and patent
indemnification provisions appearing in its General Terms of
Trade. ams AG makes no warranty, express, statutory, implied,
or by description regarding the information set forth herein.
ams AG reserves the right to change specifications and prices
at any time and without notice. Therefore, prior to designing
this product into a system, it is necessary to check with ams AG
for current information. This product is intended for use in
commercial applications. Applications requiring extended
temperature range, unusual environmental requirements, or
high reliability applications, such as military, medical
life-support or life-sustaining equipment are specifically not
recommended without additional processing by ams AG for
each application. This product is provided by ams AG “AS IS”
and any express or implied warranties, including, but not
limited to the implied warranties of merchantability and fitness
for a particular purpose are disclaimed.
ams AG shall not be liable to recipient or any third party for any
damages, including but not limited to personal injury, property
damage, loss of profits, loss of use, interruption of business or
indirect, special, incidental or consequential damages, of any
kind, in connection with or arising out of the furnishing,
performance or use of the technical data herein. No obligation
or liability to recipient or any third party shall arise or flow out
of ams AG rendering of technical or other services.
ams Datasheet
[v3-05] 2015-Oct-23
Page 87
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AS3687/87XM − Document Status
Document Status
Document Status
Product Preview
Preliminary Datasheet
Datasheet
Datasheet (discontinued)
Page 88
Document Feedback
Product Status
Definition
Pre-Development
Information in this datasheet is based on product ideas in
the planning phase of development. All specifications are
design goals without any warranty and are subject to
change without notice
Pre-Production
Information in this datasheet is based on products in the
design, validation or qualification phase of development.
The performance and parameters shown in this document
are preliminary without any warranty and are subject to
change without notice
Production
Information in this datasheet is based on products in
ramp-up to full production or full production which
conform to specifications in accordance with the terms of
ams AG standard warranty as given in the General Terms of
Trade
Discontinued
Information in this datasheet is based on products which
conform to specifications in accordance with the terms of
ams AG standard warranty as given in the General Terms of
Trade, but these products have been superseded and
should not be used for new designs
ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Revision Information
Revision Information
Changes from 1v3-4 to current revision 3-05 (2015-Oct-23)
Page
Content of austriamicrosystems datasheet was updated to latest ams design
Removed duplicated DC/DC Control2 register
Updated product name
1
Updated Figure 1
1
Updated Feedback Selection section
15
Note(s) and/or Footnote(s):
1. Page and figure numbers for the previous version may differ from page and figure numbers in the current revision.
2. Correction of typographical errors is not explicitly mentioned.
ams Datasheet
[v3-05] 2015-Oct-23
Page 89
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AS3687/87XM − Content Guide
Content Guide
1
1
2
3
General Description
Key Benefits & Features
Applications
Block Diagram
5
5
Pin Assignment
Pin Description
7
8
9
Absolute Maximum Ratings
Electrical Characteristics
Typical Operating Characteristics
13
13
15
15
16
18
18
18
19
20
21
25
26
26
30
31
32
Detailed Functional Description
Step Up DC/DC Converter
Feedback Selection
Overvoltage Protection in Current Feedback Mode
Voltage Feedback
PCB Layout Hints
Step Up Registers
Reg. Control Register (Address 00h)
DCDC Control1 Register (Address 21h)
DC/DC Control2 Register (Address 22h)
Charge Pump
Charge Pump Mode Switching
Soft Start
Charge Pump Registers
Current Sinks
High Voltage Current Sinks CURR1, CURR2, CURR6
High Voltage Current Sinks CURR1, CURR2, CURR6 Registers
Current Sinks CURR30, CURR31, CURR32, CURR33
Current Sinks CURR3x Registers
LED Pattern Generator
Soft Dimming for Pattern
LED Pattern Registers
PWM Generator
Internal PWM Generator
PWM Generator Registers
LED TEST
Function Testing for single LEDs connected to the
Charge Pump
Function Testing for LEDs connected to the Step Up
DC/DC Converter
Analog-To-Digital Converter
Application Hint: Extending the ADC Input Voltage
Range for CURR1,2,6
ADC Registers
Audio Controlled RGB LEDs (only AS3687XM)
AGC
Audio Control Registers
Power ON Reset
Reset Control Register
Temperature Supervision
Temperature Supervision Registers
34
34
40
41
43
47
47
51
54
55
55
57
58
59
61
63
65
68
70
70
71
Page 90
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ams Datasheet
[v3-05] 2015-Oct-23
AS3687/87XM − Content Guide
ams Datasheet
[v3-05] 2015-Oct-23
71
72
72
73
76
77
Serial Interface
Serial Interface Features
Device Address Selection
Serial Data Transfer Formats
Operating Modes
Register Map
81
83
85
86
87
88
89
External Components
Package Drawings & Markings
Ordering & Contact Information
RoHS Compliant & ams Green Statement
Copyrights & Disclaimer
Document Status
Revision Information
Page 91
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