SA5901 Datasheet, PDF (11/24 Pages) Silan Microelectronics Joint-stock – 4-CHANNEL MOTOR DRIVER FOR PORTABLE CD PLAYER

VSYS1= 1.20
x
R1 ⋅R3
R1 +R3
+
R2 ⋅R4
R2 +R4
R2 ⋅R4
(V)
R2 +R4
SA5901
(Short-circuit protection function)
When the output (6-pin) of error amplifier is “H”, if the voltage of SPRT pin (8-pin) has reached 1.2V (typ.) upon
charging the pin, switching of SW pin (5-pin) is disabled. Time to disable switching depends on a capacitor of the
SPRT pin (8-pin) and it can be calculated by the under-mentioned expression:
t
=
CSPRT
x
VTH
ISPRT
(sec)
(VTH = 1.20V, ISPRT = 10ȝA)
(Soft-start function)
The soft-start is functioned by putting a capacitor between DEAD pin (4-pin) and GND. MAX duty can be
changed by attaching resistance to 4-pin.
t=CDEAD X R (sec) (R=65kΩ)
(Power-off operation)
SPRT pin (8-pin) is charged by setting OFF pin (40-pin) to “L”. Then, switching of SW pin (5-pin) is terminated
when the voltage of the SPRT pin (8-pin) has reached 1.2V (typ.). time to disable switching depends on a
capacitor of the SPRT pin (8-pin) and it can be calculated by the under-mentioned expression:
t=CSPRT x
VTH
IOFF
(sec)
(VTH = 1.20V,IOFF = 20uA)
(Over-voltage protection operation)
When the voltage impressed to BSEN pin (1-pin) has been 8.4V (typ.), SPRT pin (8-pin) is charged. Then,
switching of SW pin (5-pin) is terminated when the voltage of the SPRT pin (8-pin) has reached 1.2V (typ.). time
to disable switching depends on a capacitor of the SPRT pin (8-pin) and it can be calculated by the under-
mentioned expression:
t=CSPRT x
VTH
IHV
(sec)
(VTH = 1.20V,IHV = 20uA)
“Empty” detector unit
When the voltage impressed to BSEN pin (1-pin) has been the detecting voltage or less, EMP pin (35-pin) varies
from “H”to “L”(open collector output). Hysteresis of 50mV (typ.) set to the detecting voltage to prevent the output
chattering. The detecting voltage varies depending on SEL pin (42-pin) as follows:
SEL pin
L
High-2
Detect voltage
2.2V (Typ.)
1.8V (Typ.)
Return voltage
2.25V (Typ.)
1.85V (Typ.)
Reset circuit
Upon 90% (typ.) of DC/DC converter output voltage, RESET pin (3-pin) varies from “L”to “H”and AMUTE pin
(34-pin) changes from “H”to “L”. Hysteresis of 50mV(typ.) set to the reset voltage to prevent the output chattering.
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http: www.silan.com.cn
REV:1.3 2006.02.27
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