WM8351GEB/V Wolfson Microelectronics, WM8351GEB/V Datasheet - Page 146

• Manufacturer Part Number: WM8351GEB/V
• Description: Audio CODECs Audio CODEC plus pwr management
• Manufacturer: Wolfson Microelectronics

Specifications of WM8351GEB/V

• Number Of Adc Inputs: 2
• Number Of Dac Outputs: 2
• Conversion Rate: 48 KSPS
• Interface Type: Serial (2-Wire, 3-Wire, 4-Wire)
• Resolution: 12 bit
• Operating Supply Voltage: 3.7 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: BGA
• Minimum Operating Temperature: - 25 C
• Number Of Channels: 2 ADC/2 DAC
• Supply Current: 260 uA
• Thd Plus Noise: - 83 dB
• Audio Codec Type: Stereo
• No. Of Adcs: 2
• No. Of Dacs: 2
• No. Of Input Channels: 8
• No. Of Output Channels: 6
• Adc / Dac Resolution: 24bit
• Adcs / Dacs Signal To Noise Ratio: 95dB
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8351
16 CURRENT SINKS (LED DRIVERS)
16.1 GENERAL DESCRIPTION
16.2 CONSTANT-CURRENT SINK
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The WM8351 includes four pins for driving different types of LEDs.
The ISINKA pin provides a programmable constant-current sink designed to drive a string of serially
connected LEDs, including white LEDs used in display backlights or in camera flash applications.
Using ISINKA in conjunction with DC-DC Converter 2 provides a particularly power-efficient way to
drive such LED strings. The ground connection associated with this Current Sink is the SINKGND
pin.
ISINKC, ISINKD and ISINKE are regular open-drain outputs. They are alternate functions of the
GPIO10, GPIO11 and GPIO12 pins respectively. These GPIOs are provided on the LINE power
domain; the associated ground connection is the GND pin.
ISINKA is a dedicated LED driver pin equipped with a programmable constant current sink. It is
designed to drive a string of serially connected white LEDs such as those used in display backlights
or photo-flash applications. Powering LEDs in this way is particularly power efficient because no
series resistor is required. DC-DC converter 2, operating as a current-controlled voltage source, is an
ideal power source for LED strings. This converter can generate voltages higher than BATT or LINE,
which can overcome the combined forward voltages of long LED strings (e.g. a string of 7 white
LEDs with a forward voltage of 4V requires at least 28V).
16.2.1
In Active mode, ISINKA can be enabled in software using the CS1_ENA register field defined in
Table 95. If required, the Current Sink function may also be controlled by the Hibernate bit.
Note that these control bits do not exist for ISINKC, ISINKD or ISINKE.
R14 (0Eh)
Power mgmt
(7)
R172 (ACh)
Current Sink
Driver A
Note: CS1_ENA can be accessed through R14 or through R172. Reading from or writing to either
register location has the same effect.
Table 95 Enabling ISINKA
When ISINKA is used in conjunction with DC-DC Converter 2, the ISINK should always be switched
on before the DC-DC Converter is switched on. Conversely, the DC-DC Converter should always be
switched off before the ISINK is switched off. If high voltages are used, additional external
components may also be needed to protect the WM8351.
16.2.2
The sink current for ISINKA can be programmed by writing to the CS1_ISEL register bit. The current
steps are logarithmic to match the logarithmic light sensitivity characteristic of the human eye. The
step size is 1.5dB (i.e. the current doubles every four steps).
ADDRESS
ENABLING THE SINK CURRENT
PROGRAMMING THE SINK CURRENT
BIT
15
12
0
CS1_ENA
CS1_HIB_MO
DE
LABEL
DEFAULT
0
0
Current Sink 1 enable (ISINKA pin)
0 = disabled
1 = enabled
Current Sink 1 behaviour in Hibernate
mode
0 = disable current sink in Hibernate
1 = leave current sink as in Active
PD, March 2010, Rev 4.2
DESCRIPTION
Production Data
146