Document
L9942
Integrated stepper motor driver for bipolar stepper motors with microstepping and programmable current profile
Features
■ Two full bridges for max. 1.3 A load (RDSON = 500 m)
■ Programmable current waveform with look-up table: 9 entries with 5 bit resolution
■ Current regulation by integrated PWM controller and internal current sensing
■ Programmable stepping mode: full, half, mini and microstepping
■ Programmable slew rate for EMC and power dissipation optimization
■ Programmable Fast-, Slow-, Mixed- and AutoDecay Mode
■ Full-scale current programmable with 3 bit resolution
■ Programmable stall detection
■ Step clock input for reduced µController requirements
■ Very low current consumption in standby mode IS < 3 µA, typ. Tj 85 °C
■ All outputs short circuit protected with openload, overload current, temperature warning and thermal shutdown
■ The PWM signal of the internal PWM controller is available as digital output.
■ All parameters are guaranteed for 3 V < Vcc < 5.3 V and for 7 V < Vs < 20 V
Applications
Stepper motor driver for bipolar stepper motors in automotive applications like light levelling, Bending light and Throttle control.
Table 1. Device summary
Order code
Junction temp. range, C
L9942XP1 L9942XP1TR
-40 to 150 -40 to 150
PowerSSO24
Description
The L9942 is an integrated stepper motor driver for bipolar stepper motors with microstepping and programmable current profile look-up-table to allow a flexible adaptation of the stepper motor characteristics and intended operating conditions. It is possible to use different current profiles depending on target criteria: audible noise, vibrations, rotation speed or torque. The decay mode used in PWM-current control circuit can be programmed to slow-, fast-, mixed-and autodecay. In autodecay mode device will use slow decay mode if the current for the next step will increase and the fast decay or mixed decay mode if the current will decrease. The programmable stall detection is useful in case of head lamp leveling and bending light application, by preventing to run the motor too long time in stall for position alignment. If a stall is detected, the alignment process is closed and the noise is minimized.
Package PowerSSO24 PowerSSO24
Packing Tube
Tape and reel
September 2013
Doc ID 11778 Rev 7
1/40
www.st.com
1
Contents
Contents
L9942
1 Block diagram and pin information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 Dual power supply: VS and VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 Standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3 Diagnostic functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.4 Overvoltage and undervoltage detection . . . . . . . . . . . . . . . . . . . . . . . . . . 9 .