ST735
-5V INVERTING, NEGATIVE OUTPUT
CURRENT-MODE PWM REGULATOR
s
s
s
s
s
s
s
s
s
s
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CONVERTS +4.0V TO + 6.2V INPUT TO -5V
OUTPUT
1W GUARANTEED OUTPUT POWER
75% TYPICAL EFFICIENCY
0.8mA QUIESCENT CURRENT
10µA SHUTDOWN MODE
160KHZ FIXED FREQUENCY OSCILLATOR
CURRENT MODE PWM CONVERTER
LOW NOISE AND JITTER
SOFT START
SIMPLE APPLICATION CIRCUIT
UNDERVOLTAGE LOCKOUT
DIP-8
SO-8
DESCRIPTION
The ST735 is a Bi-CMOS, inverting switch mode
DC-DC regulator with internal Power MOSFET's
that generates a fixed -5V output voltage from a
4V to 6.2V input voltage; is guaranteed an output
current of 200mA for inputs greater than 4.5V. The
quiescent current for this device is typically of
0.8mA and, in shutdown mode it is reduced to
10µA.
SCHEMATIC DIAGRAM
O
so
b
te
le
r
P
uc
od
s)
t(
bs
-O
These power-conserving features, along with high
efficiency and applications circuits, that lend itself
to minaturization, make the ST735 excellent in a
broad range of on-card, HDD and portable
equipment applications. The ST735 employ a
high performance current mode pulse with
modulation (PWM) control scheme to provide tight
output voltage regulation and low noise. The
fixed frequency oscillator is factory trimmed to
160KHz, allowing for easy noise filtering. The
regulator in production is tested to guarantee an
output accuracy within ±5% over all specified
conditions.
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August 2002
1/9
ST735
ABSOLUTE MAXIMUM RATINGS
Symbol
V
IN
SHDN
V
LX
V
FB
V
OUT
I
LX
P
tot
T
stg
T
op
Parameter
DC Input Voltage (V
IN
to GND)
Shutdown Voltage (SHDN to GND)
Switch Voltage (Lx to V
IN
)
Feedback Voltage (V
OUT
to GND)
Output Voltage (V
OUT
to GND)
Other Input Voltage (SS, CC to GND)
Peack Switch Current
Power Dissipation at T
j
= 70°C
Storage Temperature Range
Operating Junction Temperature Range
DIP-8
SO-8
Value
-0.3 to +7
-0.3 to V
+
+0.3
-12.5 to +0.3
-11 to +0.3
-11 to +0.3
-0.3 to V
+
+0.3
2
725
470
-55 to +150
-40 to +125
Unit
V
V
V
V
V
V
A
mW
°C
°C
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is
not implied.
THERMAL DATA
Symbol
R
thj-case
Parameter
Thermal Resistance Junction-case
DIP-8
2
CONNECTION DIAGRAM
(top view)
PIN DESCRIPTION
Pin N°
O
so
b
2
3
4
5
6
7
8
1
te
le
r
P
uc
od
s)
t(
so
b
-O
te
le
r
P
od
SO-8
8
s)
t(
uc
Unit
°C/W
Symbol
SHDN
V
REF
SS
CC
V
OUT
GND
LX
V
IN
Reference Output Voltage
Soft Start
Compensation Input
Negative Output Voltage
Name and Function
SHUT-DOWN Control (V
CC
=ON GND=Shutdown
Ground
Switch Output
Positive Supply - Voltage Input
2/9
ST735
TYPICAL CHARACTERISTICS
(Referred to typical application circuit, T
amb
=25°C unless otherwise specified)
Figure 1 :
Output Voltage vs Temperature
Figure 4 :
Efficency vs Temperature
Figure 2 :
Reference Voltage vs Temperature
Figure 5 :
Efficency vs Ouput Current
Figure 3 :
Oscillator Frequency vs Temperature
O
so
b
te
le
r
P
uc
od
s)
t(
bs
-O
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Figure 6 :
Supply Current vs Temperature
5/9
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