L6228 STMicroelectronics, L6228 Datasheet - Page 10

• Manufacturer Part Number: L6228
• Description: DMOS DRIVER FOR BIPOLAR STEPPER MOTOR
• Manufacturer: STMicroelectronics

L6228
CIRCUIT DESCRIPTION
POWER STAGES and CHARGE PUMP
The L6228 integrates two independent Power MOS
Full Bridges. Each Power MOS has an R
0.73 (typical value @ 25°C), with intrinsic fast free-
wheeling diode. Switching patterns are generated by
the PWM Current Controller and the Phase Se-
quence Generator (see below). Cross conduction
protection is achieved using a dead time (t
typical value) between the switch off and switch on of
two Power MOSFETSs in one leg of a bridge.
Pins VS
the supply voltage V
supply voltage in the range from 8V to 52V. It has to
be noticed that the R
cents when the supply voltage is in the range from 8V
to 12V.
Using N-Channel Power MOS for the upper transis-
tors in the bridge requires a gate drive voltage above
the power supply voltage. The bootstrapped supply
voltage V
lator and few external components to realize a
charge pump circuit as shown in Figure 6. The oscil-
lator output (VCP) is a square wave at 600KHz (typi-
cal) with 10V amplitude. Recommended values/part
numbers for the charge pump circuit are shown in Ta-
ble 1.
Table 1. Charge Pump External Components
Figure 6. Charge Pump Circuit
10/26
C
C
R
D1
D2
BOOT
P
P
A
BOOT
VCP
and VS
Values
D1
R
C
P
P
D2
is obtained through an internal Oscil-
VBOOT
B
MUST be connected together to
S
DS(ON)
C
. The device operates with a
220nF
10nF
100
1N4148
1N4148
BOOT
VS
increases of some per-
A
VS
B
D01IN1328
V
S
DT
DS(ON)
= 1 s
=
LOGIC INPUTS
Pins CONTROL, HALF/FULL, CLOCK, RESET and
CW/CCW are TTL/CMOS and uC compatible logic
inputs. The internal structure is shown in Fig. 7. Typ-
ical value for turn-on and turn-off thresholds are re-
spectively V
Pin EN (Enable) has identical input structure with the
exception that the drain of the Overcurrent and ther-
mal protection MOSFET is also connected to this pin.
Due to this connection some care needs to be taken
in driving this pin. The EN input may be driven in one
of two configurations as shown in Fig. 8 or 9. If driven
by an open drain (collector) structure, a pull-up resis-
tor R
in Fig. 8. If the driver is a standard Push-Pull structure
the resistor R
as shown in Fig. 9. The resistor R
sen in the range from 2.2K to 180K . Recommend-
ed values for R
and 5.6nF. More information on selecting the values
is found in the Overcurrent Protection section.
Figure 7. Logic Inputs Internal Structure
Figure 8. EN Pin Open Collector Driving
Figure 9. EN Pin Push-Pull Driving
PUSH-PULL
OUTPUT
COLLECTOR
OUTPUT
OPEN
EN
and a capacitor C
th(ON)
R
EN
EN
5V
EN
PROTECTION
and the capacitor C
R
= 1.8V and V
EN
C
EN
EN
C
and C
EN
EN
ESD
PROTECTION
PROTECTION
EN
EN
ESD
ESD
are connected as shown
are respectively 100K
th(OFF)
5V
D01IN1329
EN
EN
= 1.3V.
should be cho-
are connected
5V
5V
D01IN1330
D01IN1331