L6926
High efficiency monolithic synchronous step down regulator
Features
■2 V to 5.5 V battery input range
■High efficiency: up to 95%
■Internal synchronous switch
■No external Schottky required
■Extremely low quiescent current
■1 mA max shutdown supply current
■800 mA max output current
■Adjustable output voltage from 0.6 V
■Low drop-out operation: up to 100% duty cycle
■Selectable low noise/low consumption mode at light load
■Power Good signal
■± 1% output voltage accuracy
■Current-mode control
■600 kHz switching frequency
■Externally synchronizable from 500 kHz to 1.4 MHz
■OVP
■Short-circuit protection
Applications
■Battery-powered equipment
■Portable instruments
■Cellular phones
■PDAs and hand held terminals
MSOP8
VFQFPN8 (3x3x1.0 mm)
■DSC
■GPS
Description
The device is DC-DC monolithic regulator specifically designed to provide extremely high efficiency. L6926 supply voltage can be as low as 2 V allowing its use in single Li-ion cell supplied applications. Output voltage can be selected by an external divider down to 0.6 V. Duty cycle can saturate to 100% allowing low dropout operation. The device is based on a 600 kHz fixedfrequency, current mode-architecture. Low consumption mode operation can be selected at light load conditions, allowing switching losses to be reduced. L6926 is externally synchronizable with a clock which makes it useful in noisesensitive applications. Other features like powergood, overvoltage protection, short-circuit protection and thermal shutdown (150 °C) are also present.
|
|
|
|
|
5 |
LX L 6.8 µH |
|
VIN = 1.8V |
|
VIN= 2 to 5.5 V |
VCC |
|
|
|
|
|
|
|
|
|
6 |
|
|
|
R3 |
|
C2 |
||
|
RUN |
|
|
|
|
R2 |
|||
|
|
|
|
|
|
500k |
|||
C1 |
|
1 |
|
8 |
PGOOD |
10µF |
|||
|
|
|
|
200k |
|||||
SYNC |
|
|
|
|
6.3V |
||||
10µF |
7 |
|
3 |
|
|
|
|||
|
|
|
|
|
|
|
|||
6.3V |
|
|
|
|
VFB |
|
|
|
|
|
|
|
|
|
|
R1 |
|
||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2 |
4 |
|
|
100k |
|
|
|
|
|
|
|
|
|
||
|
|
COMP |
C3 |
GND |
|
|
|
|
|
|
|
|
|
220pF |
|
|
|
|
|
|
|
|
R1 |
|
|
|
|
|
|
|
|
|
10k |
|
|
|
|
|
AM10472v1 |
|
|
|
|
|
|
|
|
|
December 2011 Doc ID 9302 Rev 10 1/16
www.st.com
Contents |
L6926 |
|
|
Contents
1 |
Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
3 |
|
2 |
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
4 |
|
3 |
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
5 |
|
4 |
Operation description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
7 |
|
|
4.1 |
Modes of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
7 |
4.1.1 Low consumption mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.1.2 Low noise mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.1.3 Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
|
4.2 |
Short circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
. 8 |
|
4.3 |
Slope compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
9 |
|
4.4 |
Loop stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
9 |
5 |
Additional features and protections . . . . . . . . . . . . . . . . . . . . . . . . . . . |
10 |
5.1 DROPOUT operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.2 PGOOD (Power Good output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.3 Adjustable output voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.4 OVP (overvoltage protection) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.5 Thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 |
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
11 |
7 |
Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
14 |
8 |
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
15 |
2/16 |
Doc ID 9302 Rev 10 |
L6926 |
Pin settings |
|
|
RUN |
1 |
8 |
PGOOD |
RUN |
1 |
8 |
PGOOD |
|
|
|
|
|
|||||
COMP |
2 |
7 |
SYNC |
COMP |
2 |
7 |
SYNC |
|
VFB |
3 |
6 |
VCC |
|
|
E-pad |
|
|
VFB |
3 |
6 |
VCC |
|||||
GND |
4 |
5 |
LX |
|||||
|
|
|
|
|||||
|
D01IN1239AMOD |
|
GND |
4 |
5 |
LX |
||
|
|
|
|
|
|
|||
|
|
|
|
|
|
AM10471v1 |
|
Table 1. |
Pin description |
||
Pin n° |
Name |
Description |
|
|
|
|
|
1 |
RUN |
Shutdown input. When connected to a low level (lower than 0.4 V) the device |
|
stops working. When high (higher than 1.3 V) the device is enabled. |
|||
|
|
||
|
|
|
|
2 |
COMP |
Error amplifier output. A compensation network has to be connected to this pin. |
|
Usually a 220 pF capacitor is enough to guarantee the loop stability. |
|||
|
|
||
|
|
|
|
3 |
VFB |
Error amplifier inverting input. The output voltage can be adjusted from 0.6 V up |
|
to the input voltage by connecting this pin to an external resistor divider. |
|||
|
|
||
|
|
|
|
4 |
GND |
Ground. |
|
|
|
|
|
5 |
LX |
Switch output node. This pin is internally connected to the drain of the internal |
|
switches. |
|||
|
|
||
|
|
|
|
|
|
Input voltage. The start up input voltage is 2.2 V (typ) while the operating input |
|
6 |
VCC |
voltage range is from 2 V to 5.5 V. An internal UVLO circuit realizes a 100 mV |
|
|
|
(typ.) hysteresis. |
|
|
|
|
|
|
|
Operating mode selector input. When high (higher than 1.3 V) the Low |
|
|
|
Consumption Mode is selected. When low (lower than 0.5 V) the low noise |
|
7 |
SYNC |
mode is selected. If connected with an appropriate external synchronization |
|
|
|
signal (from 500 kHz up to 1.4 MHz) the internal synchronization circuit is |
|
|
|
activated and the device works at the same switching frequency. |
|
|
|
|
|
|
|
Power good comparator output. It is an open drain output. A pull-up resistor |
|
8 |
PGOOD |
should be connected between PGOOD and VOUT (or VCC depending on the |
|
requirements). The pin is forced low when the output voltage is lower than 90% |
|||
|
|
of the regulated output voltage and goes high when the output voltage is greater |
|
|
|
than 90% of the regulated output voltage. If not used the pin can be left floating. |
|
|
|
|
|
- |
E-Pad |
To be connected to GND plane for optimal thermal performance. |
|
|
|
|
Doc ID 9302 Rev 10 |
3/16 |
Maximum ratings |
L6926 |
|
|
Table 2. |
Absolute maximum ratings |
|
|
|
Symbol |
|
Parameter |
Value |
Unit |
|
|
|
|
|
V6 |
|
Input voltage |
-0.3 to 6 |
V |
V5 |
|
Output switching voltage |
-1 to VCC |
V |
V1 |
|
Shutdown |
-0.3 to VCC |
V |
V3 |
|
Feedback voltage |
-0.3 to VCC |
V |
V2 |
|
Error amplifier output voltage |
-0.3 to VCC |
V |
V8 |
|
PGOOD |
-0.3 to VCC |
V |
V7 |
|
Synchronization mode selector |
-0.3 to VCC |
V |
PTOT |
|
Power dissipation at TA = 70 °C |
0.45 |
W |
TJ |
|
Junction operating temperature range |
-40 to 150 |
°C |
TSTG |
|
Storage temperature range |
-65 to 150 |
°C |
LX pin |
|
Maximum withstanding voltage range test condition: |
±1000 |
V |
|
|
CDF-AEC-Q100-002- “Human body model” |
|
|
Other pins |
|
±2000 |
V |
|
|
acceptance criteria: “normal performance’ |
|||
|
|
|
|
|
Table 3. |
Thermal data |
|
|
|
Symbol |
Parameter |
Value |
Unit |
|
|
|
|
|
|
RthJA |
Maximum thermal resistance junction-ambient for MSOP8 |
180 |
°C/W |
|
|
|
|
||
Maximum thermal resistance junction-ambient for VFQFPN8 |
56 |
°C/W |
||
|
||||
|
|
|
|
4/16 |
Doc ID 9302 Rev 10 |
L6926 |
Electrical characteristics |
|
|
TJ = 25 °C, VIN = 3.6 V unless otherwise specified.
Table 4. |
Electrical characteristics (1) |
|
|
|
|
|
|
Symbol |
Parameter |
Test condition |
|
Min. |
Typ. |
Max. |
Unit |
|
|
|
|
|
|
|
|
Vcc |
Operating input voltage |
After turn on |
(1) |
2 |
|
5.5 |
V |
|
|
||||||
Vcc ON |
Turn on threshold |
|
|
|
2.2 |
|
V |
Vcc OFF |
Turn off threshold |
|
|
|
|
2 |
V |
Vcc hys |
Hysteresis |
|
|
|
100 |
|
mV |
Rp |
High side Ron |
Vcc = 3.6 V, Ilx =100 mA |
|
|
240 |
300 |
mΩ |
|
|
|
|
||||
(1) |
|
|
400 |
||||
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
Rn |
Low side Ron |
Vcc = 3.6 V, Ilx =100 mA |
|
|
215 |
300 |
mΩ |
|
|
|
|
||||
(1) |
|
|
400 |
||||
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
Peak current limit |
Vcc = 3.6 V |
|
1 |
1.2 |
1.5 |
A |
|
|
|
|
|
|||
Ilim |
(1) |
0.85 |
|
1.65 |
|||
|
|
|
|
||||
|
|
|
|
|
|
|
|
Valley current limit |
Vcc = 3.6 V |
|
1 |
1.4 |
1.7 |
A |
|
|
|
||||||
|
|
|
|
|
|||
|
(1) |
0.9 |
|
1.85 |
|||
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
VOUT |
Output voltage range |
|
|
Vfb |
|
VCC |
V |
fosc |
Oscillator frequency |
|
|
450 |
600 |
700 |
kHz |
|
|
|
|
|
|||
|
(1) |
400 |
600 |
800 |
|||
|
|
|
|
||||
|
|
|
|
|
|
|
|
fsync |
Sync mode clock (2) |
|
|
500 |
|
1400 |
kHz |
DC characteristics |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Vsync = 0 V, no load, |
|
|
200 |
300 |
|
|
Quiescent current |
VFB > 0.6 V |
|
|
|
||
|
|
|
|
|
µA |
||
Iq |
(low noise mode) |
Vsync = 0 V, no load, |
(1) |
|
|
300 |
|
|
|
|
|||||
|
|
|
|
||||
|
VFB > 0.6 V |
|
|
|
|
||
|
|
|
|
|
|
|
|
|
Quiescent current |
Vsync = Vcc, no load, |
(1) |
|
25 |
50 |
µA |
|
(low consumption mode) |
VFB > 0.6 V |
|
|
|||
|
|
|
|
|
|
||
Ish |
Shutdown current |
RUN to GND, Vcc = 5.5 V |
|
|
0.2 |
|
µA |
|
|
RUN to GND, VLX = 5.5 V, |
|
|
1 |
|
µA |
I |
LX leakage current (2) |
Vcc = 5.5 V |
|
|
|
|
|
|
|
|
|
|
|
||
lx |
|
RUN to GND, VLX = 0V, |
|
|
|
|
|
|
|
|
|
1 |
|
µA |
|
|
|
Vcc = 5.5 V |
|
|
|
|
|
Error amplifier characteristics |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Vfb |
Voltage feedback |
|
|
0.593 |
0.600 |
0.607 |
V |
|
|
|
|
|
|
||
|
(1) |
0.590 |
0.600 |
0.610 |
V |
||
|
|
|
|||||
|
|
|
|
|
|
|
|
Ifb |
Feedback input current (2) |
VFB = 0.6 V |
|
|
25 |
|
nA |
Doc ID 9302 Rev 10 |
5/16 |