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Description
GM3326 is step-up/down DC/DC converter controller ICs with fast, and low ON resistance drivers built-in. A versatile step-up/ down DC/DC converter can be realised by using with large output current only 4 basic external components - transistors, coils, diodes, and capacitors. 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. GM3326 switches from PWM to PFM control during light loads, and the series offers high efficiencies from light loads through to large output currents. 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. During shutdown (CE pin = L), consumption current can be reduced to as little as 0.5A or less.
Features
Input Voltage Range : 2.0V ~ 10V Output Voltage Range : 2.4V ~ 6.0V ( 2.5% accuracy) (selectable in 0.1V steps) Oscillation Frequency : 300KHz ( 15% accuracy) Output Current : more than 250mA (VIN=2.4V, VOUT=3.3V) Efficiency : 81% (typ) at 5.0V, 78% (typ) at 3.3V Stand-By : ISTB = 0.5A (max) Output Voltage Internal Set-Up SOT-25 Package
Application
Mobile phones PDAs Palmtop computers
TYPICAL APPLICATION CIRCUITS
Portable audio equipment Various power supplies
Schottky MBRS140
3L colis SMTSPR5D5047C-220 Youth coils YCDH57-220
L
VOUT
Nch MOSFET FDN339AN VOUT GM3326 EXT VDD GND
Pch MOSFET FDN338P
VIN
Schottky MBRS140
CL
+
CE
+ CIN 100F/ 10V Chemi_con PT- Series
68F/ 10V Chemi_con PT- Series
www.gammamicro.com
GM3326 V0.1
1
MARKING INFORMATION & PIN CONFIGURATIONS
SOT-25 (SOT-23-5)
CE
5
VOUT
4
OAVYW
1 2 3
OA: Device Code V : Output Voltage Y : Year W : Weekly
GND VDD
EXT
ORDERING INFORMATION
Ordering Number
GM3326-2.5ST25R GM3326-2.8ST25R GM3326-3.0ST25R GM3326-3.3ST25R GM3326-3.5ST25R GM3326-4.0ST25R GM3326-4.5ST25R GM3326-5.0ST25R GM3326-5.5ST25R GM3326-6.0ST25R
Output Voltage
2.5 2.8 3.0 3.3 3.5 4.0 4.5 5.0 5.5 6.0
Suffix
B E G J L Q V A F K
Package
SOT-25 SOT-25 SOT-25 SOT-25 SOT-25 SOT-25 SOT-25 SOT-25 SOT-25 SOT-25
Shipping
3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel 3,000 Units/ Tape & Reel
* For detail Ordering Number identification, please see last page.
ABSOLUTE MAXIMUM RATINGS
PARAMETER
VDD Pin Voltage VOUT Pin Voltage CE Pin Voltage
SYMBOL
VDD VOUT VCE VEXT/ IEXT/ Pd Topr Tstg
RATINGS
-0.3 ~ 12 -0.3 ~ 12 -0.3 ~ 12 -0.3 ~ VDD +0.3 100 150 -40 ~ +85 -40 ~ +125
UNITS
V V V V mA mW C C
GM3326
2
EXT/ Pin Voltage EXT/ Pin Current Power Dissipation Operating Ambient Temp. Storage Temp.
BLOCK DIAGRAM
VOUT Error Amp. +
Phase Compensation
VDD
+ PWM/ PFM Comparator Buffer, Driver EXT/
CE
VRef with Soft Start CE
PWM/ PFM Controller
Ramp Wave Generator, OSC
GND
Block Diagram Explanation
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. 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). The ramp wave generator, as the name suggests, generates the switching frequency's ramp wave. With the GM3326 series, control is automatically switched between PWM and PFM according to the size of the load. 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. 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.
GM3326
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 85 Efficiency (%) 80 75 70 65 60 55 50 45 40 2 3 4 5 6 7 8 Step-Up Mode IOUT= 10mA Set Output Voltage +0.4V Step-Down Mode 100mA 200mA
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.
85 Efficiency (%) 80 75 70 65 0.2
VIN= 2.4V VIN= 3.0V VIN= 4.5V
GM3326
0.4 VF Voltage (V)
Figure 2. VOUT= 3.3V, IOUT= 100mA
4
OPERATIONAL EXPLANATION
Schottky
L
VOUT
Nch MOSFET
Pch MOSFET
VIN
Schottky
VOUT EXT VIN CE + CL CE
GND
+ CIN

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)
VOUT= 3.3V, FOSC= 300kHz TA= 25C
PARAMETER
Output Voltage Supply Voltage Supply Current 1 Supply Current 2 Stand- By Current Oscillation Frequency Max. Duty Ratio PFM Duty Ratio Efficiency
Note 1
SYMBOL
VOUT VDD IDD 1 IDD 2 ISTB FOSC
CONDITIONS
Min
3.218 2.0
Typ
3.300 130 20 300 85 25 78 10.0 29 19
Max
3.383 10.0 200 35 0.5 345 92 35 20.0 0.20 43 27
Unit
V V A A A KHz % % % mS V V W W
VOUT= CE: Set Output Voltage X 0.95 applied VOUT= CE: Set Output Voltage + 0.5 applied VOUT= Set Output Voltage X 0.95 applied, CE= 0V
-
VDD=VOUT= CE: Set Output Voltage X 0.95 applied 255 78 15 5.0 VOUT: Set Output Voltage X 0.95 applied VOUT: Set Output Voltage X 0.95 applied Same as IDD 1, VEXT/ = VOUT - 0.4V Same as IDD 1, VEXT/ = 0.4V 0.65 -
MAXDTY VDD=VOUT= CE: Set Output Voltage X 0.95 applied PFMDTY EFFI TSS VCEH VCEL REXTBH REXTBL No load VDD=VIN= CE: Set Output Voltage X 0.95 applied
Soft- Start Time CE 'H' Voltage CE 'L' Voltage EXT/ 'H' ON Resistance EXT/ 'L' ON Resistance
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
5
SOT-25(SOT-23-5) PACKAGE OUTLINE DIMENSIONS
2.9 0.1 1.9 0.05 0.95 0.038 0.13
Pad Layout
0~0.1 1.5 0.05 2.8 0.1
0.094 2.4
0.028 0.7 0.039 1.0
0.65 0.05
0.35 0.03
0.8 0.05
0.037 0.95 0.037 0.95
5
5
0.074 1.9
( Inches ) mm
1.10 0.1
Unit: mm
ORDERING NUMBER
GM 3326 2.5 ST25 R
Shipping R: Tape & Reel Gamma Micro. Package ST25: SOT-25
GM3326
Circuit Type Output Voltage 1.5: 1.5V
6
7
GM3326

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