CS89712 datasheet(97/170 Pages) CIRRUS

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CS89712

DS502PP2

3.9.4

PMPCON Pump Control Register (address 0x8000.0400)

The Pulse Width Modulator (PWM) pump control register is a 16-bit read / write register which sets and controls the

variable mark space ratio drives for the two PWMs. All bits in this register are cleared by a system reset. (The top

four bits are unused. They should be written as zeroes, and will read as undefined).

The state of the output drive pins is latched during power on reset, this latched value is used to determine the polarity

of the drive output. The sense of the PWM control lines is summarized in Table 51.

External input pins that would normally be connected to the output from comparators monitoring the PWM output

are also used to enable these clocks. These are the FB[0:1] pins. When FB[0] is high, the PWM is disabled. The

same applies to FB[1]. They are read upon power-up.

Note:

To maximize power savings, the drive ratio fields should be used to disable the PWMs, instead of the FB

pins. The clocks that source the PWMs are disabled when the drive ratio fields are zeroed.4.

3.9.5

CODR — The CODEC Interface Data Register (address 0x8000.0440)

The CODR register is an 8-bit read / write register, to be used with the codec interface. This is selected by

the appropriate setting of bit 0 (SERSEL) of the SYSCON2 register. Data written to or read from this register

is pushed or popped onto the appropriate 16-byte FIFO buffer. Data from this buffer is then serialized and

sent to or received from the codec sound device. When the codec is enabled, the codec interrupt CSINT is

11:8

7:4

3:0

Drive 1 pump ratio

Drive 0 from AC source ratio

Drive 0 from battery ratio

Initial State of Drive 0 or

Drive 1 During Power on Reset

Sense of Drive 0

or Drive 1

Polarity of Bias

Voltage

Low

Active high

+ve

High

Active low

-ve

Table 51. Sense of PWM control lines

Bit

Description

0:3

Drive 0 from battery: This 4-bit field controls the “on” time for the Drive 0 PWM pump while the

system is powered from batteries. Setting these bits to 0 disables this pump, while setting these

bits to 1 allows the pump to be driven in a 1:16 duty ratio, 2 in a 2:16 duty ratio etc. up to a 15:16

duty ratio. An 8:16 duty ratio results in a square wave of 96 kHz when operating with an

18.432 MHz master clock.

4:7

Drive 0 from AC: This 4-bit field controls the “on” time for the Drive 0 DC to DC pump, while the

system is powered from a non-battery type power source. Setting these bits to 0 disables this

pump, setting these bits to 1 allows the pump to be driven in a 1:16 duty ratio, 2 in a 2:16 duty

ratio, etc. up to a 15:16 duty ratio. An 8:16 duty ratio results in a square wave of 96 kHz when

operating with an 18.432 MHz master clock.

Note: The CS89712 monitors the power supply input pins (i.e., BATOK and NEXTPWR) to

determine which of the above fields to use.

8:11

Drive 1 pump ratio: This 4-bit field controls the “on” time for the drive1 PWM pump. Setting

these bits to 0 disables this pump, while setting these bits to 1 allows the pump to be driven in a

1:16 duty ratio, 2 in a 2:16 duty ratio, etc. up to a 15:16 duty ratio. An 8:16 duty ratio results in a

square wave of 96 kHz when operating with an 18.432 MHz master clock.

Table 52. PMPCON

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