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3.4.4.60 DDR3PHY ZQ Impedance Control
Register 1 Name: DDR3PHY_ZQ0CR1 Offset: 0x184 Reset: 0x0000007B Property: Read/Write
Bit 31 30 29 28 27 26 25 24 Access Reset
Bit 23 22 21 20 19 18 17 16 Access Reset
Bit 15 14 13 12 11 10 9 8 Access Reset
Bit 7 6 5 4 3 2 1 0 ZPROG[7:0] Access R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 1 1 1 1 0 1 1
Bits 7:0 – ZPROG[7:0] Impedance Divide
Ratio Selects the external
resistor divide ratio to be used to set the output impedance and the on-die
termination.ZPROG[3:0] (decimal) RZQ =240±1% Programmed Zo
(Ohms) DDR3/DDR3L DDR2 LPDDR2/3 5 – – 80 7 – – 60 9 – – 48 11 40 40 40 13 34 – 34 – – 18(1) –
ZPROG[7:4] (decimal) Programmed ODT (Ohms) DDR3/DDR3L DDR2 2 120 150 5 – 75 6 60 – 7 – 50 9 40 –
Note:
To program 18 ohms, see Custom
Calibration . Using different RZQ values
in the range of 240–300 ohms, different impedance values may be obtained. ODT and driver output impedance are calibrated independently. For a detailed calibration procedure,
see Impedance
Calibration .
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