wm9001 Wolfson Microelectronics plc, wm9001 Datasheet - Page 15

• Manufacturer Part Number: wm9001
• Description: 1w Dual-mode Class Ab/d Speaker Driver
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
DEVICE DESCRIPTION
INTRODUCTION
POWER ON RESET
ENABLE
w
The WM9001 is a powerful mono speaker driver, which can operate in class D or AB mode, providing
total flexibility to the system designer. The WM9001 can deliver 1W in class D mode, Figure 2 , or in
class AB mode, Figure 3, into an 8Ω load. The input can be configured either as a single channel
differential line output offering good noise rejection characteristics, or as a single-ended line output
for systems where there is no differential option.
It can be used as a stand-alone device, or in conjunction with a CODEC such as the WM8991 or
WM8990 to provide a complete stereo solution. The gain settings and speaker driver mode are
configurable via the hardware control pins BSEL[2:0] and CDMODE. For stand-alone operation these
pins are tied to logic 1/0.
The class D amplifier requires a clock signal. An internal oscillator can be used for stand alone
operation by tying the SYNC pin to logic 1/0. Alternatively an external clock can be used by applying
this signal to the SYNC pin. The EN (Enable) pin provides a controllable method for switching
ON/OFF the speaker outputs.
The very small 3 x 3mm QFN packages make the WM9001 ideal for portable systems, such as
mobile phones, portable navigation devices, media players, laptop computers and electronic
dictionaries.
The WM9001 includes an internal Power-On Reset (POR) circuit which is used to reset the device
into a default state at power up. The POR circuit is controlled by the AVDD power supply. Note that
there is no POR on the SPKVDD supply.
When the chip is powered down, the speaker driver outputs, SPKP and SPKN, become tri-state.
The chip is enabled by a logic '1' on the EN pin.
Table 1 Device Enable Control
The EN pin should be used to disable the device prior to removing the audio or clock (removing an
external clock will not disable the output). When the chip is disabled, the speaker driver outputs
become tri-state.
The EN pin is compatible with low voltage (eg. 1.8v) logic levels from external devices, and can
accept logic 1 digital inputs as low as 1.6V, even though the WM9001 AVDD supply minimum is
2.7V. This provides compatibility with a low voltage DVDD on a controlling device such as the
WM8991 CODEC.
Ultra low quiescent current in the disabled state minimises extends battery life in this condition. The
typical values of SPKVDD current and AVDD current in the disabled (Standby) state are described in
the Electrical Characteristics section.
PIN
14
NAME
EN
Device Enable input
0 = Device Disabled
1 = Device Enabled
DESCRIPTION
PP, June 2009, Rev 3.2
WM9001
15