DRV201_15 Datasheet, PDF (20/29 Pages) Texas Instruments – DRV201 Voice Coil Motor Driver for Camera Auto Focus

DRV201
SLVSB25C – AUGUST 2011 – REVISED JUNE 2015
Typical Application (continued)
8.2.1 Design Requirements
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Table 8. Design Parameters
DESIGN PARAMETER
Supply voltage
Motor Winding
Resistance
Motor Winding
Inductance
Actuator Size
Lens in the VCM
Weight of VCM
TTL
FB
REFERENCE
Vin
RL
IL
EXAMPLE VALUE
3.7
15 Ω
100 µH
8.5 x 8.5 x 3.4 (mm)
M6 (Pitch: 0.35)
75 mg
4.2 mm
1.1 mm
8.2.2 Detailed Design Procedure
8.2.2.1 User Example 1
In Figure 21, lens settling time and settling window shows how lens control is defined. Below is an example
case how the lens is controlled and what settling time is achieved:
Measured VCM resonance frequency = 100 Hz
• According to Table 1, VCM_FREQ[7:0] = ‘10111111’ (reg 0x07h)
VCM resonance frequency, f_VCM, variation is within ±10% (minimum 90 Hz, maximum 110 Hz)
• 1/f_VCM ringing compensation is used : RING_MODE = ‘1’ (reg 0x06h)
Stepping the lens by 50 µm
• The lens is settled into a ±5-µm window within 10 ms (1/f_VCM)
8.2.2.2 User Example 2
If the case is otherwise exactly the same, but VCM resonance frequency cannot be guaranteed to stay at more
than ±30% variation, slower ringing compensation should be used:
Measured VCM resonance frequency = 100 Hz
• According to Table 1, VCM_FREQ[7:0] = ‘10111111’ (reg 0x07h)
VCM resonance frequency, f_VCM, variation is within ±30% (minimum 70 Hz, maximum 130 Hz)
• 2/f_VCM ringing compensation is used : RING_MODE = ‘0’ (reg 0x06h)
Stepping the lens by 50 µm
• The lens is settled into a ±5-µm window within 20 ms (2/f_VCM)
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