AMIS30421C4211G ONSEMI [ON Semiconductor], AMIS30421C4211G Datasheet - Page 25

• Manufacturer Part Number: AMIS30421C4211G
• Description: Micro-Stepping Stepper Motor Bridge Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Logic Supply Regulator
supply the digital part of the chip itself, some low−voltage
analog blocks and external circuitry. See Table 4 for the
limitations.
Over− and Undervoltage
below V
the drivers again the V
V
above V
drop below V
also Figure 5.
Start−Up Behavior
applied and after a certain power up time (t
voltage regulator V
V
start−up. The WDb−pin will be kept low for an additional
100ms (t
time t
Junction Temperature Calculation
thermal resistance junction−to−ambient must be known.
When only a PCB heat sink is used, a typical value is
30°C/W (see Table 4).
calculated for.
BBUH
DDH
AMIS−30421 has an on−chip 3.3V low−drop regulator to
AMIS−30421 has undervoltage detection. If V
Overvoltage detection is also present. If the voltage rises
Figure 4 gives the start−up of AMIS−30421. After V
To calculate the junction temperature of AMIS−30421 the
There are three modes the junction temperature can be
DSPI
, the internal POR will be released and the digital will
.
BBOH
BBUL
POR
, SPI communication can be initiated.
). After the WDb−pin is deactivated and after a
BBOL
, the drivers are disabled. To be able to enable
the drivers are disabled. The voltage needs to
DD
to be able to enable the driver again. See
will start−up. When V
BB
voltage needs to rise above
POWER SUPPLY AND THERMAL CALCULATION
PU
DD
), the internal
gets above
BB
http://onsemi.com
drops
BB
is
25
•
•
•
In Sleep Mode (<SLP> = ‘1’) the V
maximum 150 mA making T
In Normal Mode when the driver is disabled
(<MOTEN> = ‘0’), the V
20 mA (no external load on VDD−pin). The junction
temperature can be calculated as next:
For an 18 V application operating at an ambient
temperature of 125°C this would give:
In Normal Mode with the driver enabled (<MOTEN> =
‘1’) the gate charge current needs to be included in the
calculations.
For an 18 V application driving external MOSFET’s with
an input capacitance of 1 nF this would result in:
Operating at 125°C ambient temperature this result in a
junction temperature of:
T
T
I
I
I
T
T
BAT
BAT
BAT
J
J
J
J
+ 125° C ) 18 V
+ 135.8° C
+ 125° C ) 18 V
+ 137° C
T
+ 20 mA ) 6
+ 20 mA ) 6
+ 22.3 mA
J
+ T
A
) V
BAT
BAT
12.8 V
V
j
20 mA
22.3 mA
REGH
= T
consumption is maximum
I
BAT
amb
BAT
.
1 nF
Rth
C
30° C W
ISS
consumption is
30° C W
JA
30 kHz
f
PWM