Description
Features
GM3326 is step-up/down DC/DC converter controller ICs
Input Voltage Range : 2.0V ~ 10V
with fast, and low ON resistance drivers built-in. A versatile
Output Voltage Range : 2.4V ~ 6.0V ( ± 2.5%
step-up/ down DC/DC converter can be realised by using
accuracy) (selectable in 0.1V steps)
with large output current only 4 basic external components
Oscillation Frequency : 300KHz ( ± 15%
- transistors, coils, diodes, and capacitors.
accuracy)
Output voltage is selectable in 0.1V steps within a 2.4V ~
6.0V ( ± 2.5% accuracy) range, and switching frequency is
set at or 300KHz.
Output Current : more than 250mA (VIN=2.4V,
GM3326 switches from PWM to PFM control during light
loads, and the series offers high efficiencies from light
loads through to large output currents.
Efficiency : 81% (typ) at 5.0V, 78% (typ) at 3.3V
Soft-start time is internally set to 10 msec, which offers
protection against rush currents when the power is
switched on and also against voltage overshoot.
SOT-25 Package
VOUT=3.3V)
Stand-By : ISTB = 0.5µA (max)
Output Voltage Internal Set-Up
During shutdown (CE pin = L), consumption current can be
reduced to as little as 0.5µA or less.
Application
Mobile phones
PDAs
Palmtop computers
Portable audio equipment
Various power supplies
TYPICAL APPLICATION CIRCUITS
Schottky
MBRS140
3L colis SMTSPR5D5047C-220
Youth coils YCDH57-220
L
VOUT
Nch MOSFET
FDN339AN
VOUT
68µF/ 10V
Chemi_con
PT- Series
Schottky
MBRS140
VDD
GND
+
CIN
100µF/ 10V
Chemi_con
PT- Series
www.gammamicro.com
GM3326 V0.1
CL
CE
VIN
EXT
GM3326
+
Pch MOSFET
FDN338P
1
MARKING INFORMATION & PIN CONFIGURATIONS
SOT-25 (SOT-23-5)
CE
VOUT
5
4
OA: Device Code
V : Output Voltage
Y : Year
W : Weekly
OAVYW
1
3
2
EXT
GND
VDD
ORDERING INFORMATION
Output Voltage
Suffix
Package
Shipping
GM3326-2.5ST25R
2.5
B
SOT-25
3,000 Units/ Tape & Reel
GM3326-2.8ST25R
2.8
E
SOT-25
3,000 Units/ Tape & Reel
GM3326-3.0ST25R
3.0
G
SOT-25
3,000 Units/ Tape & Reel
GM3326-3.3ST25R
3.3
J
SOT-25
3,000 Units/ Tape & Reel
GM3326-3.5ST25R
3.5
L
SOT-25
3,000 Units/ Tape & Reel
GM3326-4.0ST25R
4.0
Q
SOT-25
3,000 Units/ Tape & Reel
GM3326-4.5ST25R
4.5
V
SOT-25
3,000 Units/ Tape & Reel
GM3326-5.0ST25R
5.0
A
SOT-25
3,000 Units/ Tape & Reel
GM3326-5.5ST25R
5.5
F
SOT-25
3,000 Units/ Tape & Reel
GM3326-6.0ST25R
6.0
K
SOT-25
3,000 Units/ Tape & Reel
Ordering Number
* For detail Ordering Number identification, please see last page.
ABSOLUTE MAXIMUM RATINGS
SYMBOL
RATINGS
UNITS
VDD Pin Voltage
VDD
-0.3 ~ 12
V
VOUT Pin Voltage
VOUT
-0.3 ~ 12
V
VCE
-0.3 ~ 12
V
EXT/ Pin Voltage
VEXT/
-0.3 ~ VDD +0.3
V
EXT/ Pin Current
IEXT/
± 100
mA
Power Dissipation
Pd
150
mW
Operating Ambient Temp.
Topr
-40 ~ +85
°C
Storage Temp.
Tstg
-40 ~ +125
°C
PARAMETER
GM3326
CE Pin Voltage
2
BLOCK DIAGRAM
VOUT
VDD
Phase Compensation
Error Amp.
+
+
-
Buffer, Driver
EXT/
PWM/ PFM
Comparator
CE
VRef with
Soft Start
CE
PWM/ PFM
Controller
Ramp Wave
Generator,
OSC
GND
Block Diagram Explanation
<Error Amp.>
The error amplifier is used as an output voltage monitor. It compares the reference voltage with the feedback from the
voltage divided by the internal resistor. Should a voltage higher than the reference voltage be fedback, the output of the
error amp will increase.
<PWM Comparator>
The PWM comparator compares the output of the error amp with the ramp wave. When the voltage at the output of the error
amp is low, the EXT/ pin will be LOW level (Switching ON time).
<Ramp Wave Generator>
The ramp wave generator, as the name suggests, generates the switching frequency's ramp wave.
<PWM / PFM Controller>
With the GM3326 series, control is automatically switched between PWM and PFM according to the size of the load.
<Vref with Soft Start, CE>
The start up of the Vref voltage at the error amp's input is gradual due to the internal capacitor and low current circuit.
Because of this soft-start function, the operations of the error amp's 2 inputs are balanced and the EXT/ pin's ON time can
be manipulated to produce longer ON times.
GM3326
Further, with the UVLO function, the signal will be such so as not to turn the MOS switch ON until any instability in the
internal circuit stabilizes during soft-start time. Even in cases where input voltage is so low as to produce instability in the IC,
the UVLO function will operate and the MOS switch will be turned OFF.
3
[Step-up&down DC/DC Converter]
Set output voltage obtained as a result of the automatic switching operations of the IC regardless of the difference between
input voltage and set output voltage.
90
Efficiency (%)
85
80
75
70
IOUT= 10mA
65
60
200mA
100mA
Set Output Voltage +0.4V
55
50
Step-Up Mode
Step-Down Mode
45
40
2
3
4
5
6
7
8
Input Voltage (V)
Figure 1. Input Voltage vs. Efficiency
The above graph shows that over a wide input voltage range, the efficiency of the GM3326 is more or less constant. In
applications that use either a standard dry 3 cell battery or a cell lithium Ion battery to obtain an output of 3.3V, for example,
the efficiency of GM3326 is again much better. Due to GM3326 does not have a series regulator output, we recommend a
test with samples for use in applications where ripple voltage is a problem.
External Components Selection (Notes)
The performance of the DC/DC converter IC circuit is heavily reliant upon the performance of the surrounding circuitry and
components. In particular, since the VF voltage of the Schottky Diode used will have a direct effect upon efficiency, the
smaller the diode, the better the efficiency obtainable. (Refer to the graph below)
It is also recommended that a switching MOSFET with a small ON resistance be used. With GM3326, an ON resistance of
500mW or less is recommended.
Efficiency (%)
85
80
75
GM3326
VIN= 3.0V
VIN= 4.5V
70
65
0.2
4
VIN= 2.4V
0.4
VF Voltage (V)
Figure 2. VOUT= 3.3V, IOUT= 100mA
OPERATIONAL EXPLANATION
Schottky
L
Pch MOSFET
VOUT
VIN
Nch
MOSFET
Schottky
VOUT EXT
VIN
CE
+
CE
GND
CL
+
CIN
<Circuit Connection Example>
GM3326 is PWM (PWM/ PFM switching) step-up/down DC/DC converter controller ICs. Gm3326 switches to PFM
operations during light loads and is very efficient over a wide range in relation to load. Further, the efficiency can be
maintained over a wide input voltage range as both step-up & step-down operations are PWM controlled. Output voltage
settings are laser trimmed.
[ON TIME]
P-Ch MOSFET = ON, N-Ch MOSFET = ON : Current flows from VIN via Pch MOSEFT, L, Nch FET to GND : L is charged.
[OFF TIME]
P-Ch MOSFET (PSW) = OFF, N-Ch MOSFET (NSW) = OFF : Current flows from GND via Schottky 1, L, Schottky 2, to
VOUT : VOUT rises due to the charge stored at L. By comparing VOUT with the internal reference voltage, the ON TIME vs
OFF TIME ratio can be regulated & output stability can be protected.
ELECTRICAL CHARACTERISTICS (GM3326- 3.3V)
TA= 25°C
Min
Typ
Max
Unit
3.218
3.300
3.383
V
2.0
-
10.0
V
130
200
µA
20
35
µA
-
0.5
µA
300
345
KHz
PARAMETER
SYMBOL
Output Voltage
VOUT
Supply Voltage
VDD
Supply Current 1
IDD 1
VOUT= CE: Set Output Voltage X 0.95 applied
-
Supply Current 2
IDD 2
VOUT= CE: Set Output Voltage + 0.5 applied
-
Stand- By Current
ISTB
VOUT= Set Output Voltage X 0.95 applied, CE= 0V
-
Oscillation Frequency
FOSC
VDD=VOUT= CE: Set Output Voltage X 0.95 applied 255
CONDITIONS
Max. Duty Ratio
MAXDTY VDD=VOUT= CE: Set Output Voltage X 0.95 applied
78
85
92
%
PFM Duty Ratio
PFMDTY
15
25
35
%
-
78
-
%
5.0
10.0
20.0
mS
Efficiency
Note 1
EFFI
No load
VDD=VIN= CE: Set Output Voltage X 0.95 applied
Soft- Start Time
TSS
CE 'H' Voltage
VCEH
VOUT: Set Output Voltage X 0.95 applied
0.65
-
-
V
CE 'L' Voltage
VCEL
VOUT: Set Output Voltage X 0.95 applied
-
-
0.20
V
Same as IDD 1, VEXT/ = VOUT - 0.4V
-
29
43
W
Same as IDD 1, VEXT/ = 0.4V
-
19
27
W
EXT/ 'H' ON Resistance
EXT/ 'L' ON Resistance
REXTBH
REXTBL
Measuring Condition: Unless otherwise stated, VDD = 3.3V, IOUT = 130mA
Note 1: EFFI= {[(Output Voltage) X (Output Current)] [(Input Voltage) X (Input Current)]} X100
GM3326
VOUT= 3.3V, FOSC= 300kHz
5
SOT-25(SOT-23-5) PACKAGE OUTLINE DIMENSIONS
2.9 ± 0.1
1.9 ± 0.05
0.13
0.95 ± 0.038
Pad Layout
0.028
0.7
0~0.1
1.5 ± 0.05
0.039
1.0
2.8 ± 0.1
0.094
2.4
0.65 ± 0.05
0.8 ± 0.05
0.35 ± 0.03
0.037
0.95
5°
0.037
0.95
0.074
1.9
5°
1.10 ± 0.1
Unit: mm
ORDERING NUMBER
GM 3326 2.5 ST25 R
Shipping
R: Tape & Reel
Gamma Micro.
GM3326
Package
ST25: SOT-25
6
Circuit Type
Output Voltage
1.5: 1.5V
( Inches
mm )
7
GM3326