S1F78100Y2A Epson Electronics America, Inc., S1F78100Y2A Datasheet - Page 159

• Manufacturer Part Number: S1F78100Y2A
• Description: High Precision Voltage Regulators
• Manufacturer: Epson Electronics America, Inc.

S1F76300 Series
Reference voltage generator and output
voltage regulator
The reference voltage generator regulates V
ate a votlage for the voltage regulator and voltage detec-
tion circuits.
The voltage regulator regulates the boosted output
votlage. This is determined by the level at point A be-
tween the two resistors connecting V
series use an on-chip resistor to set the output at a speci-
fied voltage.
Note
In step-up voltage operation, the ripple voltage created
by the switching operation is large relative to the output
voltage described above. This ripple voltage is affected
by external components and load conditions. The user
is advised to check this voltage carefully.
Voltage detection
The S1F76310, S1F76380 series are equipped with a
built-in voltage detection function. The detection volt-
age, V
Power-on clear function
The S1F76310 series and S1F76380 series are equipped
with a built-in power-on clear function. As shown in
the following figure, R1 and C1 are connected to
PWCR, and R2 is connected to RST to operate the func-
tion. If V
PWCR and RST are grounded. If V
higher than V
age hysteresis is 5% (Typ.) and V
(Typ.).
4–14
Reference
generator
DET
voltage
I1
, is fixed internally at 1.05
drops below V
REL
, Tr1 turns OFF. The detection volt-
+
–
oscillator
CR
voltage regulator
DET
Output
, Tr1 and Tr2 conduct and
REL
I1
O
A
recovers and rises
and GND. These
0.05V.
is V
I1
DET
V
V
V
GND
to gener-
I1
SW
O
1.05
EPSON
V
PWCR increases and Tr2 turns OFF, so that RST re-
turns to V
cient of R1 and C1. Thus, after normal output has been
obtained, a reset pulse of adjustable width can be ob-
tained which can reset a system connected to RST.
The output from RST is an N-channel, open-drain.
When V
V
ducts and the output is grounded. The characteristic re-
sponse is shown in the following figure.
Disabling power-on clear
Always connect PWCR to either V
age detection only is required, remove the resistor be-
tween PWCR and V
neither function is required, connect PWCR to GND.
Leaving PWCR unconnected results in an undefined in-
verter gate voltage in the V
currents to flow between V
O
I1
PWCR
drops below V
returns to its normal value when the voltage of
RST
V
S1F76310M
I1
V
V
V
V
V
V
V
I1
I1
REL
DET
O
GND
O
GND
O
exceeds V
detector
Voltage
after a delay specified by the time coeffi-
–
+
DET
O
DET
and monitor the level at RST. If
again, the output transistor con-
, the drain is opened and, when
O
O
Tr1
and GND.
circuit, causing transient
Tr2
O
or GND. If volt-
V
O
Technical Manual
S1F70000 Series
RST
PWCR
V
V
O
O
R2
R1
C1