GS-R24P
1.8W TO 8W STEP-DOWN SWITCHING REGULATOR FAMILY
PRELIMINARY
FEATURE
■
■
■
■
■
■
■
■
■
MTBF 1 000 000 hours (T
amb
=25
)
C)
1.5A max output current
35V max input voltage
1.5V max drop-out voltage
Remote logic inhibit/enable
Not-latching overload and short circuit
protection
Thermal shutdown
Fixed or adjustable output
No heatsink required
Packing type: V = vertical PTH
DESCRIPTION
The GS-R24P series is a family of high efficiency
step down switching voltage regulator, designed to
replace linear regulators.
Based on STM L5973 device, this non isolated family
of regulators are suitable for the full spectrum of ap-
plications including telecom, industry, computer and
distributed power system applications having a wide-
ly ranging input voltage.
Packing type: H = horizontal PTH
-------------------S
= horizontal SMD
June 2004
This is preliminary information on a new product now in development. Details are subject to change without notice.
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GS-R24P
SELECTION CHART
Type
Ordering
Number
GS-R24(P)0181.5
GS-R24(P)0251.5
GS-R24(P)0331.5
GS-R24(P)0501.5
GS-R24(P)0001.5
Output
Voltage
[V]
1.8
± 4%
2.5
±
4
%
3.3
±
4
%
5.0
±
4
%
1.235
÷
5.5
Input
Voltage
[V]
16
÷
35
16
÷
35
16
÷
35
16
÷
35
16
÷
35
Output
Ripple
[mVpp]
35
35
35
35
50
Efficiency
[%]
72
76
82
85
68
÷
85
Package
(P)*
H-S-V
H-S-V
H-S-V
H-S-V
H-S
Notes
Fixed output
voltage
Fixed output
voltage
Fixed output
voltage
Fixed output
voltage
Progr. output
voltage
* Packing Legend (P)
H = horizontal through hole
S = horizontal SMD
V = vertical through hole
ABSOLUTE MAXIMUM RATINGS
Symbol
V
i
I
out
V
4
V
6
T
stg
T
op
T
op1
Parameter
DC Input Voltage (for GS-R24(P)XXX1.5)
Maximum Output Current
INH
FB
Storage Temperature Range
Operating Ambient Temperature
Operating Ambient Temperature with current derating
Value
36
int. limit
-0.3 to V
i
4
-40
÷
105
-25
÷
70
-25
÷
85
V
V
°C
°C
°C
Unit
V
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GS-R24P
CONNECTION DIAGRAM AND MECHANICAL DATA
GS-R24Vxxx1.5
GS-R24Hxxx1.5
GS-R24Sxxx1.5
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GS-R24P
PIN DESCRIPTION
Pin
1
2
3
4
5
6
Function
Input +
Input/Output GND
V
out
INH
V
out-c
FB
DC input voltage
Return for input/output voltage source
Regulated power output
A logical level (active high) disables the device, when it is open an internal pull
up disables the device
Regulated output point for additional compensation
Feedback input, available on adjustable device and on request for additional
compensation
Description
ELECTRICAL CHARACTERISTICS All versions
(T
amb
=25
)
C, unless otherwise specified.)
Symbol
V
r
Parameter
Ripple Voltage
Temperature Stability
I
o
I
oL
I
q
f
s
SRV
R
th
Output Current
Current Limit
Quiescent Current
Switching Frequency
Supply Voltage Rejection
Thermal Resistance
Case to ambient
Test Condition
V
i
=24V I
o
= 1.5A
V
i
=V
o
+ 1.5V I
o
= 1.5A
V
i
=16
÷
35V
V
i
=16
÷
35V
V
i
=24V I
o
= 0A
V
i
=24V I
o
= 1.5A
225
0
2.5
1.8
250
1.5
3.5
2.5
275
Min.
Typ.
35
Max.
50
Unit
mVpp
mV/°C
A
A
mA
kHz
mV/V
°C/W
ELECTRICAL CHARACTERISTICS for horizontal versions only
(T
amb
=25
)
C, unless otherwise specified.)
Symbol
I
qst-by
INH
Parameter
Total Stand-by Quiescent
Current
INH Threshold Voltage
Test Condition
V
inh
>2.2V V
i
= 35V
Device ON
Device OFF
V
FB
Feedback Voltage
V
i
=16
÷
35V I
o
= 0
÷
1.5A
2.2
1.22
1.235
1.25
Min.
Typ.
80
Max.
150
0.8
Unit
µ
A
V
V
V
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GS-R24P
USER NOTES
Input Voltage
The recommended operating maximum DC Input Voltage is 35V inclusive of ripple voltage.
Inhibit function
The inhibit feature allows to put in stand-by mode the device.
With INH pin 4 higher than 2.2V the device is disabled and the power consumption is reduced to less than
150µA for V
i
= 35V.
With INH pin lower than 0.8V, the device is enabled.
If the INH pin is left floating, an internal pull up ensures that the voltage at the pin reaches the inhibit threshold
and the device is disabled.
The pin is also V
i
compatible.
Current protection
The device has two current limit protections, pulse by pulse and frequency fold back.
The current is sensed through a resistor and if reaches the threshold, the on time is reduced and consequently
the output voltage too.
Since the minimum switch ON time (necessary to avoid false overcurrent signal) is not enough to obtain a suf-
ficiently low duty cycle at 250 Hz, the output current, in strong overcurrent or short circuit conditions, could in-
crease again.
For this reason the switching frequency is also reduced, so keeping the inductor current under its maximum
threshold.
The frequency depends on the feedback voltage.
As the feedback voltage decreases (due to the reduced duty cycle), the switching frequency decrease too.
Thermal shutdown
The shutdown block generates a signal that turns off the power stage if the temperature of the internal chip goes
higher than a fixed internal threshold (150 ºC).
The sensing element of the chip is very close to the PDMOS area, so ensuring an accurate and fast temperature
detection.
An hysteresis of approximately 20ºC avoids that the devices turns on and off continuously.
Thermal Characteristics
Output voltage programming (GS-R24H(S)0001.5 only)
The GS-R24P output voltage is 5.54V ±4%, to reduce this value connect a resistor between pin 6 (FB) and
pin 5 (V
out-c
).
The resistor must be located very close to the proper pins, to minimize the injected noise (see figure 1).
The resistor value is calculated using the following formula:
Rv=[(V
out
-1.235)*11.3]/(5.54-V
out
)
--[kOhm]
V
out
can be adjusted between 1.235V (Rv=0 Ohm) and 5.54V (Rv=open)
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