ISO
2
-CMOS
MT91L60/61
3 Volt Multi-Featured Codec (MFC)
Data Sheet
Features
•
•
Single 2.7-3.6 volt supply operation
MT91L61 version features a delayed framing
pulse in SSI and ST-BUS modes to facilitate
cascaded devices
Programmable
µ-Law/A-Law
Codec and Filters
Programmable ITU-T (G.711)/sign-magnitude
coding
Programmable transmit, receive and side-tone
gains
Fully differential interface to handset transducers
- including 300 ohm receiver driver
Flexible digital interface including ST-BUS/SSI
Serial microport
Low power operation
ITU-T G.714 compliant
Multiple power down modes
Ordering Information
MT91L61AE
24 Pin PDIP
MT91L60AE
24 Pin PDIP
MT91L61AS
24 Pin SOIC
MT91L60AS
20 Pin SOIC
MT91L61AN
24 Pin SSOP
MT91L60AN
20 Pin SSOP
MT91L60ASR
20 Pin SOIC
MT91L61ASR
24 Pin SOIC
MT91L61ASR1 24 Pin SOIC*
MT9160AN1
20 Pin SSOP*
*Pb Free Matte Tin
-40°C to +85°C
March 2006
•
•
•
•
•
•
•
•
•
Tubes
Tubes
Tubes
Tubes
Tubes
Tubes
Tape & Reel
Tape & Reel
Tape & Reel
Tubes
Applications
•
•
•
•
•
•
Battery operated equipment
Digital telephone sets
Cellular radio sets
Local area communications stations
Pair Gain Systems
Line cards
VSSD
VDD
VSSA
VBias
VRef
FILTER/CODEC GAIN
M-
ENCODER
DECODER
7dB
-7dB
Transducer
Interface
M+
HSPKR +
HSPKR -
Din
Dout
STB/F0i
CLOCKin
STBd/FOod
(MT91L61only)
Flexible
Digital
Interface
Timing
ST-BUS
C&D
Channels
Serial Microport
A/µ/IRQ
PWRST
IC
CS
DATA1
DATA2
SCLK
Figure 1 - Functional Block Diagram
1
Zarlink Semiconductor Inc.
Zarlink, ZL and the Zarlink Semiconductor logo are trademarks of Zarlink Semiconductor Inc.
Copyright 1999-2006, Zarlink Semiconductor Inc. All Rights Reserved.
MT91L60/61
Description
Data Sheet
The MT91L60/61 3 V Multi-featured Codec incorporates a built-in Filter/Codec, gain control and programmable
sidetone path as well as on-chip anti-alias filters, reference voltage and bias source. The device supports both ITU-
T and sign- magnitude A-Law and
µ-Law
requirements. The MT91L60/61 is a true 3 V device employing a fully
differential architecture to ensure wide dynamic range.
Complete telephony interfaces are provided for connection to handset transducers. Internal register access is
provided through a serial microport compatible with various industry standard micro-controllers.
The MT91L60/61 is fabricated in Zarlink's ISO
2
-CMOS technology ensuring low power consumption and high
reliability.
2
Zarlink Semiconductor Inc.
MT91L60/61
MT91L60AS/AN
VBias
VRef
NC
PWRST
IC
A/µ/IRQ
VSSD
CS
NC
SCLK
DATA1
DATA2
Data Sheet
MT91L60AE
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
M+
M-
VSSA
NC
HSPKR +
HSPKR -
VDD
CLOCKin
NC
STB/F0i
Din
Dout
MT91L61AE/AS/AN
VBias
VRef
NC
PWRST
IC
A/µ/IRQ
VSSD
CS
NC
SCLK
DATA1
DATA2
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
M+
M-
VSSA
NC
HSPKR +
HSPKR -
VDD
CLOCKin
STBd/FOod
STB/F0i
Din
Dout
VBias
VRef
PWRST
IC
A/µ/IRQ
VSSD
CS
SCLK
DATA1
DATA2
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
M+
M-
VSSA
HSPKR +
HSPKR -
VDD
CLOCKin
STB/F0i
Din
Dout
20 PIN SOIC/SSOP
24 PIN PDIP
24 PIN PDIP/SOIC/SSOP
Figure 2 - Pin Connections
Pin Description
Pin #
20 Pin24 Pin
1
2
3
4
5
1
2
4
5
6
Name
V
Bias
V
Ref
Description
Bias Voltage (Output).
(V
DD
/2) volts is available at this pin for biasing external
amplifiers. Connect 0.1
µF
capacitor to V
SSA
.
Reference Voltage for Codec (Output).
Used internally. Nominally [Vdd/2 - 1.1]
volts. Connect 0.1
µF
capacitor to V
SSA
.
PWRST
Power-up Reset (Input).
CMOS compatible input with Schmitt Trigger (active low).
IC
Internal Connection.
Tie externally to V
SSD
for normal operation.
A/µ/IRQ
A/µ
- When internal control bit DEn = 0 this CMOS level compatible input pin governs
the companding law used by the filter/Codec;
µ-Law
when tied to V
SSD
and A-Law
when tied to V
DD
. Logically OR’ed with A/µ register bit.
IRQ
- When internal control bit DEn = 1 this pin becomes an open-drain interrupt
output signalling valid access to the D-Channel registers in ST-BUS mode.
V
SSD
CS
SCLK
Digital Ground.
Nominally 0 volts.
Chip Select (Input).
This input signal is used to select the device for microport
data transfers. Active low. CMOS level compatible.
Serial Port Synchronous Clock (Input).
Data clock for microport. CMOS level
compatible.
6
7
8
9
7
8
10
11
DATA 1
Bidirectional Serial Data.
Port for microprocessor serial data transfer. In
Motorola/National mode of operation, this pin becomes the data transmit pin only
and data receive is performed on the DATA 2 pin. Input CMOS level compatible.
DATA 2
Serial Data Receive.
In Motorola/National mode of operation, this pin is used for
data receive. In Intel mode, serial data transmit and receive are performed on the
DATA 1 pin and DATA 2 is disconnected. Input CMOS level compatible.
D
out
Data Output.
A high impedance three-state digital output for 8 bit wide channel
data being sent to the Layer 1 transceiver. Data is shifted out via this pin concurrent
with the rising edge of the bit clock during the timeslot defined by STB, or according
to standard ST-BUS timing.
10
12
11
13
3
Zarlink Semiconductor Inc.
MT91L60/61
Pin Description (continued)
Pin #
20 Pin24 Pin
12
14
Name
D
in
Description
Data Sheet
Data Input.
A digital input for 8 bit wide channel data received from the Layer 1
transceiver. Data is sampled on the falling edge of the bit clock during the timeslot
defined by STB, or according to standard ST-BUS timing. Input level is CMOS
compatible.
13
15
STB/F0i
Data Strobe/Frame Pulse (Input).
For SSI mode this input determines the 8 bit
timeslot used by the device for both transmit and receive data. This active high
signal has a repetition rate of 8 kHz. Standard frame pulse definitions apply in ST-
BUS mode. CMOS level compatible input.
STBd/F0
Delayed Frame Pulse Output.
In SSI mode, an 8 bit wide strobe is output after the
first strobe goes low. In ST-BUS mode, a frame pulse is output after 4 channel
od
(MT91L6 timeslots.
1 only)
CLOCKin
Clock (Input).
The clock provided to this input pin is used for the internal device
functions. For SSI mode connect the bit clock to this pin when it is 512 kHz or
greater. Connect a 4096 kHz clock to this input when the available bit clock is
128 kHz or 256 kHz. For ST-BUS mode connect C4i to this pin. CMOS level
compatible.
V
DD
Positive Power Supply (Input).
Nominally 3 volts.
16
14
17
15
16
17
18
19
20
18
19
20
22
23
24
3,9,
16,21
HSPKR-
Inverting Handset Speaker (Output).
Output to the handset speaker (balanced).
HSPKR+
Non-Inverting Handset Speaker (Output).
Output to the handset speaker
(balanced).
V
SSA
M-
M+
NC
Analog Ground (Input).
Nominally 0 volts.
Inverting Microphone (Input).
Inverting input to microphone amplifier from the
handset microphone.
Non-Inverting Microphone (Input).
Non-inverting input to microphone amplifier
from the handset microphone.
No Connect.
(24 Packages only). Pin 16 is NC for MT91L60.
Overview
The 3 V Multi-featured Codec (MFC) features complete Analog/Digital and Digital/Analog conversion of audio signals
(Filter/Codec) and an analog interface to a standard handset transmitter and receiver (Transducer Interface). The receiver
amplifier is capable of driving a 300 ohm load.
Each of the programmable parameters within the functional blocks is accessed through a serial microcontroller port
compatible with Intel MCS-51
®
, Motorola SPI
®
and National Semiconductor Microwire
®
specifications. These
parameters include: gain control, power down, mute, B-Channel select (ST-BUS mode), C&D channel
control/access, law control, digital interface programming and loopback. Optionally the device may be used in a
controllerless mode utilizing the power-on default settings.
4
Zarlink Semiconductor Inc.
MT91L60/61
Functional Description
Filter/Codec
Data Sheet
The Filter/Codec block implements conversion of the analog 0-3.3 kHz speech signals to/from the digital domain
compatible with 64 kb/s PCM B-Channels. Selection of companding curves and digital code assignment are
programmable. These are ITU-T G.711 A-law or
µ-Law,
with true-sign/Alternate Digit Inversion or true-sign/Inverted
Magnitude coding, respectively. Optionally, sign-magnitude coding may also be selected for proprietary
applications.
The Filter/Codec block also implements transmit and receive audio path gains in the analog domain. A
programmable gain, voice side-tone path is also included to provide proportional transmit speech feedback to the
handset receiver. This side tone path feature is disabled by default. Figure 3 depicts the nominal half-channel and
side-tone gains for the MT91L60/61.
In the event of PWRST, the MT91L60/61 defaults such that the side-tone path is off, all programmable gains are set
to 0dB and ITU-T
µ-Law
is selected. Further, the digital port is set to SSI mode operation at 2048 kb/s and the FDI
and driver sections are powered up. (See Microport section.)
The internal architecture is fully differential to provide the best possible noise rejection as well as to allow a wide
dynamic range from a single 3 volt supply design. This fully differential architecture is continued into the Transducer
Interface section to provide full chip realization of these capabilities for the handset functions.
A reference voltage (V
Ref
), for the conversion requirements of the Codec section, and a bias voltage (V
Bias
), for
biasing the internal analog sections, are both generated on-chip. V
Bias
is also brought to an external pin so that it
may be used for biasing external gain setting amplifiers. A 0.1µF capacitor must be connected from V
Bias
to analog
ground at all times. Although V
Ref
may only be used internally, a 0.1µF capacitor must be connected from V
Ref
to
ground. The analog ground reference point for these two capacitors must be physically the same point. To facilitate
this the V
Ref
and V
Bias
pins are situated on adjacent pins.
The transmit filter is designed to meet ITU-T G.714 specifications. The nominal gain for this filter is 0 dB (gain
control = 0 dB). Gain control allows the output signal to be increased up to 7 dB. An anti-aliasing filter is included.
This is a second order lowpass implementation with a corner frequency at 25 kHz.
The receive filter is designed to meet ITU-T G.714 specifications. The nominal gain for this filter is 0 dB (gain control
= 0 dB). Gain control allows the output signal to be attenuated up to 7 dB. Filter response is peaked to compensate
for the sinx/x attenuation caused by the 8 kHz sampling rate.
Side-tone is derived from the input of the Tx filter and is not subject to the gain control of the Tx filter section. Side-
tone is summed into the receive handset transducer driver path after the Rx filter gain control section so that Rx
gain adjustment will not affect side-tone levels. The side-tone path may be enabled/disabled with the gain control
bits located in Gain Control Register 2 (address 01h).
Transmit and receive filter gains are controlled by the TxFG
0
-TxFG
2
and RxFG
0
-RxFG
2
control bits, respectively.
These are located in Gain Control Register 1 (address 00h). Transmit filter gain is adjustable from 0dB to +7dB and
receive filter gain from 0dB to -7dB, both in 1dB increments.
Side-tone filter gain is controlled by the STG
0
-STG
2
control bits located in Gain Control Register 2 (address 01h).
Side-tone gain is adjustable from
-9.96 dB to +9.96 dB in 3.32 dB increments.
Companding law selection for the Filter/Codec is provided by the A/µ companding control bit while the coding
scheme is controlled by the Smag/ITU-T control bit. The A/µ control bit is logically OR’ed with the A/µ pin providing
access in both controller and controllerless modes. Both A/µ and Smag/ITU-T reside in Control Register 2 (address
04h). Table 1 illustrates these choices.
5
Zarlink Semiconductor Inc.
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