Block Diagram(Stepping Motor(S) × 2-ch Control Mode)
TC78S122FNG
CW/CCW_X
CLK_X
X_MODE1
X_MODE2
MODE0
MODE1
MODE2
ENABLE_X
RESET_X
ALERT
VREF_X
VM
RS_A
RS_B
RS_C
RS_D
Step Decoder
(Input Logic)
Current Level Set
Torque Control
2bit D/A
(Angle Control)
Current Feedback (×2)
VRS1
RS COMP1
VRS2
RS COMP2
VMR Detect
VCC Voltage
Regulator
Chopper OSC
OSC
CR-CLK
Converter
Output Control
(Mixed Decay Control)
SLEEP
VCC
OSCM
Output
(H-Bridge ×2)
Output
(H-Bridge ×2)
VM
ISD
TSD
VMR
Detect
Detection Circuit
Stepping
Motor
Stepping
Motor
* "X" means the ellipsis of AB / CD of each Ch. (CW/CCW_X, CLK_X, X_MODE1, X_MODE2,
ENABLE_X, and RESET_X)
Note: GND wiring: We recommend that a heat sink be grounded at all points, and the board be grounded at
only one GND pin for single point ground. Take the heat dissipation into consideration when designing
the board. When in controlling the setting pins for each mode by SW, those pins should be pulled up to
power supply like VCC or pulled down to GND not to go into a high-impedance (Hi-Z) state.
Utmost care is necessary in the design of the output line, VM line and GND line since IC may be
destroyed due to short-circuit between outputs, to supply, or to ground.
Especially for those pins that are connected to power supply and get a large current flow (such as VM,
RS, OUT and GND), they should be properly wired; otherwise troubles including destruction may
occur to this IC. If the logic input pins are not wired properly, malfunction that would destroy the IC
may occur due to a large current exceeding the absolute maximum ratings. Care should be taken in the
design of board layouts and implementation of the IC.
2
2017-09-15
