GM7109
150KHz, 2A STEP DOWN VOLTAGE
SWITCHING REGULATORS
Description
GM7109 series is designed to provide all the
active function for a
step-down (buck) switching
regulator, and drives a maximum load current as
high as 2A
line and load regulations. GM7109 is
available
in fixed output voltages of 3.3V, 5V,
and a versatile Adjustable output version.
These regulators are simple to use and require
minimum number of external components. The
features include internal frequency compensation
and a fixed-frequency oscillator.
The GM7109 is high-efficiency replacements for
popular
three-terminal linear regulators, and is
requiring a smaller heat sink or even no need
heat sink.
GM7109 performs well with standard inductors
from most
of manufacturers, and simplifying the
design of switch-mode
power supplies.
External
shutdown is included with 80 µA (typical) standby
current. The output switch has cycle-by-cycle
current limiting as well as thermal shutdown for
full protection under fault conditions.
GM7109 operates at a switching frequency of
150 kHz which
allowing smaller size filter
components than what would be needed with
lower frequency switching regulators.
GM7109 series are available in a standard 8-lead
SO package or 8 lead SO package with heat
sink.
Features
Standard SOP8 & PSOP8 package
3.3V, 5V, and Adjustable output versions
Adjustable version output voltage range
1.23V to 37V
V
OUT
accuracy is to
±
2% under specified
input voltage the output load conditions
Input voltage range up to 40V
Requires only 4 external components with
High efficiency
TTL shutdown capability, low power
standby mode
Built-in thermal shutdown, current limit
protection
Uses standard inductors
150 kHz fixed frequency internal oscillator
Application
Pre-regulator for linear regulators
High-efficiency step-down buck regulator
On-card/board switching regulators
Positive to negative converter (buck-boost)
LCD Monitors
Typical Application Circuits
GM7109-5.0
1
Unregulated
DC Input
FB
3
1
V
IN
Output
2
C
IN
680µF
SD
4
GND
5, 6, 7, 8
D1
1N5824
L1
68µH
5V
regulated
outpu
t,
C
OUT
220µF
www.gammamicro.com.tw
GM7109
V1.00
1
GM7109
150KHz, 2A STEP DOWN VOLTAGE
SWITCHING REGULATORS
Marking Information and Pin Configurations (Top View)
SO8 & PSO8
GND
GND
GND
GND
GM7109
VVVAYWW
V
IN
V
OUT
SD
FB
VVV: 033=3.3V, 050=5.0V, 00A=ADJ
A: Assembly / Testing factory code
Y: Year
WW: Week
Ordering Information
Ordering Number
GM7109-AS8T
GM7109-AS8R
GM7109-APS8T
GM7109-APS8R
GM7109-3.3S8T
GM7109-3.3S8R
GM7109-3.3PS8T
GM7109-3.3PS8R
GM7109-5.0S8T
GM7109-5.0S8R
GM7109-5.0PS8T
GM7109-5.0PS8R
Output Voltage
Adj
Adj
Adj
Adj
3.3
3.3
3.3
3.3
5.0
5.0
5.0
5.0
Package
SOP8
SOP8
PSOP8
PSOP8
SOP8
SOP8
PSOP8
PSOP8
SOP8
SOP8
PSOP8
PSOP8
Shipping
100 Units / Tube
2500 Units / Reel
100 Units / Tube
2500 Units / Reel
100 Units / Tube
2500 Units / Reel
100 Units / Tube
2500 Units / Reel
100 Units / Tube
2500 Units / Reel
100 Units / Tube
2500 Units / Reel
GM7109
V1.00
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GM7109
150KHz, 2A STEP DOWN VOLTAGE
SWITCHING REGULATORS
Absolute Maximum Ratings
(Note 1)
Rating
Maximum Supply Voltage
SD Pin Input Voltage / Feed Back Pin Voltage
Output Voltage to Ground (Steady State)
Power Dissipation
Thermal Resistance – Junction to Ambient (θ
JA
)
Storage Temperature Range
Maximum Junction Temperature
Operating Temperature Range
Minimum EDS Rating (Note 2)
Lead Temperature (Soldering, 10 sec)
** 2 square inch of FR-4, double sided, 1oz. minimum copper weight, is
recommended
Value
45
-0.3 + V
IN
+ 0.3
-0.3 + V
IN
+ 0.3
Internally Limited
36
- 65 to 150
+ 150
- 40 to 125
2
+ 260
Unit
V
V
V
-
℃/W
℃
℃
℃
kV
℃
Block Diagram
SD
V
IN
Current
Source
Bias
1.235V
Reference
2.5V
Reference
Start UP
COMP
2.5V
Current
Limit
COMP
GM
R2
AMP
COMP
R1 = 2.5K
Reset
Freq. Shift
150KHz
OSC
Thermal
Limit
OUTPUT
Latch
Driver
2A
Switch
220mV
220
For 3.3V, R2 = 4.2K
For 5.0V, R2 = 7.6K
For Adj, R2 = 0 and R1 = OPEN
GND
GM7109
V1.00
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GM7109
150KHz, 2A STEP DOWN VOLTAGE
SWITCHING REGULATORS
Electrical Characteristics: GM7109-ADJ
(Specifications with standard type face are for T = 25℃, and those with bold face type apply over full Operating Temperature
rage
)
Parameter
Output Voltage
Efficiency
Condition
4.5V
<
V
IN
<
40V, 0.2A
<
I
LOAD
<
2A
V
IN
=12V, I
LOAD
=2.0A, V
OUT
= 3V
Symbol
V
OUT
η
Min
1.193
1.180
Typ
1.230
88
Max
1.267
1.280
Unit
V
%
Electrical Characteristics: GM7109-3.3
(Specifications with standard type face are for T = 25℃, and those with bold face type apply over full Operating Temperature
rage)
Parameter
Output Voltage
Efficiency
Condition
4.75V
<
V
IN
<
40V, 0.2A
<
I
LOAD
<
2A
V
IN
=12V, I
LOAD
=2.0A
Symbol
V
OUT
η
Min
3.168
3.135
Typ
3.300
73
Max
3.432
3.465
Unit
V
%
Electrical Characteristics: GM7109-5.0
(Specifications with standard type face are for T = 25℃, and those with bold face type apply over full Operating Temperature
rage)
Parameter
Output Voltage
Efficiency
Condition
7V
<
V
IN
<
40V, 0.2A
<
I
LOAD
<
2A
V
IN
=12V, I
LOAD
=2.0A
Symbol
V
OUT
η
Min
4.800
4.7500
Typ
5.000
80
Max
5.200
5.250
Unit
V
%
GM7109
V1.00
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GM7109
150KHz, 2A STEP DOWN VOLTAGE
SWITCHING REGULATORS
Electrical Characteristics: All Output Voltage Versions
(Specifications with standard type face are for T
J
= 25℃, and those with bold face type apply over full Operating Temperature
rage. Unless otherwise specified, V
IN
= 12V)
Parameter
Feedback Bias
Current
Oscillator
Frequency
Saturation
Voltage
Max Duty Cycle
(ON)
Min Duty Cycle
(OFF)
Current Limit
Output Leakage
Current
Quiescent
Current
Standby
Quiescent
Current
SD Pin
Logic
lnput Level
SD Pin lnput
Current
Condition
V
FB
=1.3V (Adjustable Version Only)
Symbol
I
b
Min
-
127
110
Typ
10
Max
50
100
173
173
Unit
nA
(Note 6)
f
o
150
kHz
I
OUT
= 2A (Notes 7, 8)
(Note 8)
(Note 9)
Peak Current (Notes 7, 8)
Output =0V (Notes 7, 9, 10)
Output = -0.9V (Note 10)
(Note 9)
SD Pin = 5V (OFF), Note 10
Low (ON)
High (OFF)
V
LOGlC
= 2.5V (OFF)
V
LOGlC
= 0.5V (ON)
V
SAT
DC
DC
l
CL
l
L
l
Q
l
STBY
V
IH
V
IL
I
H
I
L
-
1.16
100
0
1.4
1.5
-
V
%
%
A
3.4
-
-
-
-
-
2.0
-
2
5
70
1.3
1.3
5
0.02
100
-
-
200
0.6
-
15
5
µA
mA
mA
µA
V
µA
µA
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating
Ratings indicate conditions for which the device is intended to be functional, but do not
guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical
Characteristics.
Note 2:
The human body model is a 100pF capacitor discharged through a 1.5KΩresistor into each pin.
Note 3:
Typical numbers are at 25°C and represent the most likely norm.
Note 4:
All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type
face). All room temperature limits are 100% production tested. All limits at temperature extremes are
guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to
calculate Average Outgoing Quality Level (AOQL).
Note 5:
External components such as the catch diode, inductor, input and output capacitors, and voltage
programming resistors can affect switching regulator system performance. When the GM7109 is used as
shown in the Figure 1 test circuit, system performance will be as shown in system parameters section of
Electrical Characteristics.
Note 6:
The switching frequency is reduced when the second stage current limit is activated.
Note 7:
No diode, inductor or capacitor connected to output pin.
Note 8:
Feedback pin removed from output and connected to 0V to force the output transistor switch ON.
Note 9:
Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the ADJ. version.
GM7109
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