GHz PLL with
I
2
C Bus
and Four Chip Addresses
MGP 3006X6
Bipolar IC
Features
q
q
q
q
q
q
1-chip system for MPU-control (I
2
C Bus)
4 programmable chip addresses
Short pull-in time for quick channel switch-over
and optimized loop stability
3 high-current band switch outputs (20 mA)
Software-compatible with SDA 3202 series
Oxis III technology
P-DSO-16-1
Type
MGP 3006X6
MGP 3006X6
Ordering Code
Q67000-H5113
Q67006-H5113
Package
P-DSO-16-1 (SMD)
P-DSO-16-1 Tape & Reel (SMD)
Combined with a VCO (tuner), the
MGP 3006X6
device, with four hard-switched chip
addresses, forms a digitally programmable phase-locked loop for use in television sets
with PLL-frequency synthesis tuning. The PLL permits precise crystal-controlled setting
of the frequency of the tuner oscillator between 16 and 1300 MHz in increments of
62.5 kHz, and, with a 2.4-GHz prescaler 1/2, in the TV-SAT band in increments of
125 kHz. The tuning process is controlled by a microprocessor via an
I
2
C Bus. The
I
2
C Bus noise immunity has been improved by a factor of 10 compared to the
SDA 3202-2, and the new crystal oscillator generates a sinusoidal signal, suppressing
the higher-order harmonics, which reduces the moiré noise considerably.
Semiconductor Group
1
04.93
MGP 3006X6
Circuit Description
Tuning Section
UHF/VHF
REF
The tuner signal is capacitively coupled at the UHF/VHF-input and
subsequently amplified.
The reference input REF should be decoupled to ground using a capacitor
of low series inductance. The signal passes through an asynchronous
divider with a fixed ratio of
P
= 8, an adjustable divider with ratio
N
= 256
through 32767, and is then compared in a digital frequency/phase
detector to a reference frequency
f
REF
= 7.8125 kHz.
This frequency is derived from a balanced, low-impedance 4-MHz crystal
oscillator (pin Q1, Q2) by dividing its output signal by
Q
= 512.
The phase detector has two outputs UP and DOWN that drive the two
current sources I+ and I– of a charge pump. If the negative edge of the
divided VCO-signal appears prior to the negative edge of the reference
signal, the I+ current source pulses for the duration of the phase
difference. In the reverse case the I– current source pulses.
PD, UD
If the two signals are in phase, the charge pump output (PD) goes into the
high-impedance state (PLL is locked). An active low-pass filter integrates
the current pulses to generate the tuning voltage for the VCO (internal
amplifier, external output transistor at UD and external RC-circuitry). The
charge pump output is also switched into the high-impedance state when
the control bit T0 = 1. Here it should be noted, however, that the tuning
voltage can alter over a long period in the high-impedance state as a
result of self-discharge in the peripheral circuitry. UD may be switched off
by the control bit OS to allow external adjustments.
By means of a control bit 5I the pump current can be switched between
two values by software. This programmability permits alteration of the
control response of the PLL in the locked-in state. In this way different
VCO-gains in the different TV-bands can be compensated, for example.
P0, P1, P2
P4, P7
CAU
The software-switched outputs P0, P1, P2 can be used for direct band
selection (20 mA current output).
P4 and P7 are general-purpose open-collector outputs. The test bit T1 = 1
switches the test signal Cy (divided input signal) to P7.
Four different chip addresses can be set by appropriate connection of pin
CAU.
Q1, Q2
Semiconductor Group
2
MGP 3006X6
I
2
C Bus Interface
Data are exchanged between the processor and the PLL on the
I
2
C Bus.
SCL, SDA
The clock is generated by the processor (input SCL), while pin SDA works
as an input or output depending on the direction of the data (open
collector; external pull-up resistor). Both inputs have hysteresis and a
low-pass characteristic, which enhances the noise immunity of the
I
2
C
Bus.
The data from the processor pass through an
I
2
C Bus control. Depending
on their function the data are subsequently stored in registers. If the bus
is free, both lines will be in the marking state (SDA, SCL are high). Each
telegram begins with the start condition and ends with the stop condition.
Start condition: SDA goes low, while SCL remains high. Stop condition:
SDA goes high while SCL remains high. All further information transfer
takes place during SCL = low, and the data is forwarded to the control
logic on the positive clock edge.
The table “bit allocation” should be referred to in the following paragraph.
All telegrams are transmitted byte-by-byte, followed by a ninth clock
pulse, during which the control logic returns the SDA-line to low
(acknowledge condition). The first byte is comprised of seven address
bits. These are used by the processor to select the PLL from several
peripheral components (chip select). The eighth bit is always low.
In the data portion of the telegram the first bit of the first or third data byte
determines whether a divider ratio or control information is to follow. In
each case the second byte of the same data type or a stop condition has
to follow the first byte.
V
S
, GND
When the supply voltage is applied a power-on reset circuit prevents the
PLL from setting the SDA-line to low, which would block the bus.
Semiconductor Group
3
MGP 3006X6
Circuit Description
(cont’d)
Bit Allocation
MSB
Address byte
1
1
0
0
0
MA1
A = Acknowledge
MA0
0
A
Prog. divider Byte 1
0
n14
n13
n12
n11
n10
n9
n8
A
Prog. divider Byte 2
n7
n6
n5
n4
n3
n2
n1
n0
A
Control info. Byte 1
1
5I
T1
T0
X
X
1
OS
A
Control info. Byte 2
Divider Ratio
P7
X
X
P4
X
P2
P1
P0
A
N = 16384
×
n14 + 8192
×
n13 + 4096
×
n12 + 2048
×
n11 + 1024
×
n10 + 512
×
n9 +
256
×
n8 + 128
×
n7 + 64
×
n6 + 32
×
n5 + 16
×
n4 + 8
×
n3 + 4
×
n2 + 2
×
n1 + n0
Band Selection
P0, P1, P2, P4, P7 = 1
Open-collector output is active.
Pump Current Programming
5I = 1
UD Disable
OS = 1
Test Mode
T1, T0 = 0, 0
T1 = 1
T0 = 1
Semiconductor Group
High current
UD is disabled.
Normal operation
P3 =
f
REF
; P4 = Cy
Tristate: charge pump output PD is in high-impedance state.
4
MGP 3006X6
Chip Address Switching
MA1
0
0
1
1
MA0
0
1
0
1
Voltage at CAU
(0 … 0.1)
V
S
open-circuit
(0.4 … 0.6)
V
S
(0.9 … 1)
V
S
Telegram Examples
Start-Addr-DR1-DR2-CW1-CW2-Stop
Start-Addr-CW1-CW2-DR1-DR2-Stop
Start-Addr-DR1-DR2-CW1-Stop
Start-Addr-CW1-CW2-DR1-Stop
Start-Addr-DR1-DR2-Stop
Start-Addr-CW1-CW2-Stop
Start-Addr-DR1-Stop
Start-Addr-CW1-Stop
Start
Addr
DR1
DR2
CW1
CW2
Stop
=
=
=
=
=
=
=
start condition
address
divider ratio 1st byte
divider ratio 2nd byte
control word 1st byte
control word 2nd byte
stop condition
Semiconductor Group
5
微控制器 MCU
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