February 1999
PBM 3960/1
Microstepping Controller/
Dual Digital-to-Analog Converter
Description
PBM 3960/1 is a dual 7-bit+sign, Digital-to-Analog Converter (DAC) especially
developed to be used together with the PBL 3771/1, Precision Stepper Motor driver
in micro-stepping applications. The circuit has a set of input registers connected to an
8-bit data port for easy interfacing directly to a microprocessor. Two registers are
used to store the data for each seven-bit DAC, the eighth bit being a sign bit (sign/
magnitude coding). A second set of registers are used for automatic fast/slow current
decay control in conjunction with the PBL 3771/1, a feature that greatly improves
high-speed micro-stepping performance. The PBM 3960/1 is fabricated in a high-
speed CMOS process.
Key Features
• Analog control voltages from 3 V
down to 0.0 V.
• High-speed microprocessor interface.
• Automatic fast/slow current decay
control.
• Full-scale error
±1
LSB.
• Interfaces directly with TTL levels and
CMOS devices.
• Fast conversion speed, 3
µs.
• Matches PBL 3771.
PBM 3960/1
WR
C
D
E1
CS
C
D
R
Level 2
DA- Data 1
R
Level 1
Digit
Comp
E1
C
E
D
CD 1
DA
E
E2
A0
E3
C
D
A1
E4
D7 - D0
C
D
R
R
DA- Data 2
R
D/A
1
E
D/A
Digit
Comp
E4
C
D
R
DA
E
P
B
M
B /1
P 60
2
CD 2
E
Sign 2
POR
RESET
R
V
ss
22-pin plastic DIP
28-pin plastic PLCC
Figure 1. Block Diagram.
M
39
E
Sign 1
39
60
/1
V
DD
V
Ref
ERICSSON [ ERICSSON ]
