Datasheet

V
EXTIO
Rbias
(
DACA_gain ) 1
)
ƒ
vco
+
ƪ
(M)
(N)
ƫ
ƒ
ref
DAC5688
www.ti.com SLLS880C –DECEMBER 2007–REVISED AUGUST 2010
Register name: CONFIG27 Address: 0x1B, Default 0xFF
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
coarse_daca(3:0) coarse_dacb(3:0)
1 1 1 1 1 1 1 1
coarse_daca(3:0) : Scales the output current is 16 equal steps.
coarse_dacb(3:0) : Same as above except for DACB.
Register name: CONFIG28 Address: 0x1C, Default 0x00
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved
0 0 0 0 0 0 0 0
Register name: CONFIG29 Address: 0x1D, Default 0x00
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
PLL_m(4:0) PLL_n(2:0)
0 0 0 0 0 0 0 0
PLL_m : M portion of the M/N divider of the PLL thermometer encoded:
PLL_m(4:0) M value
00000 1
00001 2
00011 4
00111 8
01111 16
11111 32
All other values Invalid
PLL_n : N portion of the M/N divider of the PLL thermometer encoded. If supplying a high rate CLK2/C frequency, the PLL_n value
should be used to divide down the input CLK2/C to maintain a maximum PFD operating of 160 MHz.
PLL_n(2:0) n value
000 1
001 2
011 4
111 8
All other values Invalid
PLL Function:
where ƒ
ref
is the frequency of the external DAC clock input on the CLK2/C pins
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