USB 2.0 USB 2.0 Design Guide Solid State System Co., LTD.
USB Differential Impedance Differential Impedance EMI20H USB
Cable Cable
VCCTx
Unbalance Mode Common Mode Single Ended
VCCRx
VCCTx+
Balance Mode DifferentialRx+
VCC
Tx-
Rx-
USB Low Speed USB 1.0 Full Speed USB 1.1 High Speed USB 2.0 1.5M
BPS 12M BPS 480M BPS 73 ~ 300 ns 4 ~ 20 ns 0.5 ns 2V 2V 400mV 45
Differential Differential Differential
1. 100MHz Ohms Law 2. 200MHz Micro Strip/Strip Line 3. 800MHz 4.
USB 2.0 480M BPSHighLow 240MHz
NRZI CodingRZReturn to Zero1 0 0 1 1 0 1 1 1 0 0 1 0
NRZINone Return to Zero Inversed1 0 0 1 1 0 1 1 1 0 0 1 0
NRZI
0 1
Micro Strip/Strip Line
R
L
Trace
D+ D+ DPlan
D-
Plan
RLC
Return LossZ1
Z2
Z1 = Z2
Return Loss= = PIncident / PReflection
20 log
Z1 + Z2 Z1 Z2
Micro Strip/Strip LineMicro StripD+ w s Dw h t w s w t D+ Dh
b
Strip Line
sTrace Space wTrace Width tTrace Thickness hDistance Between
Signal and Copper Plan bThickness of PCB Laminate or Substrate
rDielectric Constant
Micro Strip Differential ImpedanceSingle Line Trace Impedance Z0
= 60/(0.475r+0.67)1/2 ln[4h/0.67/(0.8w+t)] Z0 = 87/(r+1.41)1/2
ln[5.98h/(0.8w+t)] 1 < r < 15 and 0.1 < h/w < 2.0
Signal Pair Differential Impedance Zdiff = 2Z0(1-0.48e-0.96 s/h)
rmm
Strip Line Differential ImpedanceSingle Line Trace Impedance Z0
= 60/r1/2 ln[4b/0.67//(0.8w + t)] Z0 = 60/r1/2 ln[1.9b/(0.8w + t)]
w/h < 0.35 and t/h < 0.25 Signal Pair Differential Impedance
Zdiff = 2Z0(1-0.347e-2.9 s/h) rmm
Micro Strip 1.6mm r 4.5 4.5 4.5 w 0.184mm 0.4mm 0.7mm s 0.184mm
0.4mm 0.3mm t 0.035mm 0.04mm 0.04mm h 0.11mm 0.3mm 0.3mm Z0 46 57
39 Zdiff 82 106 63
A B
1. USB 2.0 80 ~ 100 2. 82Trace 90
D+ D-
D+ D-
D+ D-
X
Stub
39
39
D+ D39
D+ D39
X
Pad
PCB
VCC1 DGND
D+ D-
D+ D-
VCC2 AGND
PCBD+ DDGND VCC1 AGND VCC2
D+ / D-
D+ / DThrough Hole
USB 2.0 Low Speed/Non-Periodic Signal 20mil GND SignalTop Side
D+ D7.5mil 7.5mil 7.5mil PrepregFR4 r = 4.5 High Speed / Periodic
SignalClock 1 ounce0.035mm 50mil 4.5mil
Substrate or Laminate Vcc PrepregFR4 r = 4.5 SignalBottom
Side
53mil
63mil1.6mm
4.5mil
1 mil = 1/1000 inch = 0.0254mm Intel 1.6mm
1. 5% 2. X7RY5V Z5U NPO
XIN
R1
XOUT
Y1
R2
C1
C2
1. SMD Crystal 2. 3. 8mil ~ 12 mil 5mil PCMCIA 30% 4.
MLCC X-55 Y-30 Z+10
NPOC0G 0.25% ~ 10% -55 ~ +125 30ppm ~ 0.5pF 2.5%
X7R 5% ~ 20% -55 ~ +125 15% 7.5% 4+65 5+85 6+105 7+125 8+150
Y5V 20% -20% ~ +80% -30 ~ +85 +22% ~ -82% 20%
Z5U 20% -20% ~ +80% +10 ~ +85 +22% ~ -56% 20%
A0.1% B1.5% C2.2% D3.3% E4.7% F7.5% P10% R15% S22% T+22%~33%
U+22%~-56% V+22%~-82%
Bypass CapacitorIC VCC VCC VCC 0.1uF GND IC VCC VCC
0.1uF GND
X
1. Bypass Capacitor IC 2. IC
ESD L
ESD
LED
X 2%
0.5mm ComponentTraceCopper Plan
Pad
TSOP 48 WSOP 48
TSOP 48 WSOP 48
X
TSOP 48 WSOP 48
20H EMI 20h h
Vcc GND
20h D+ D-
VccGND Prepreg
USB Pin 1 VBUS Pin 2 DPin 3 D+ Pin 4 GND
PVC 65% PE GND
DVBUS D+
28 AWG 20 AWG
Drain WireLow Speed/USB 1.0/1.5M bps PE
CableVBUS GND 28 28 AWG D+ D- 28 28 AWG 60mm 80mmUSB 1.0 Low
Speed 1.5M bps USB 1.1 Full Speed 12M bps VBUSGND 125mV
Differential Impedance 90 +/- 15% Delay 5.2ns/mTotal Delay 26ns 65%
Shielding Resistance 0.6 ASDM-D-4566 DCR 5% USB 2.0 7.1.17 Cable
Attenuation Table 7-6 0 50 -20 +60 +20 UL 94V-0 USB 2.0 6.7
Electrical, Mechanical, and Environmental Compliance Standards,
Table 6-7 USB 1.0 Low Speed 1.5M bps USB 1.1 Full Speed 12M bps D+
D- Drain Wire
USB 2.0 Cable AttenuationFrequency 64KHz 256KHz 512KHz 772KHz
1MHz 4MHz 8MHz 12MHz 24MHz 48MHz 96MHz 200MHz 400MHz Maximum
Attenuation 0.08dB 0.11dB 0.13dB 0.15dB 0.20dB 0.39dB 0.57dB 0.67dB
0.95dB 1.35dB 1.90dB 3.20dB 5.80dB
ASTM-D-4566AWG 28 26 24 22 20 /100 m 23.20 14.60 9.09 5.74
3.58
Cable DelayUSB 2.0 Maximum One-Way Signal Propagation Delay 30ns
Cable Delay< 5.2ns/m Total Cable Delay< 26ns
Host Delay < 3ns
Device Delay < 1ns Max.
Shielding DC Resistance< 0.6
Layout
