1/13
L6920
February 2005
1 Features
0.6 TO 5.5V OPERATING INPUT VOLTAGE
1V START UP INPUT VOLTAGE
INTERNAL SYNCHRONOUS RECTIFIER
ZERO SHUT DOWN CURRENT
3.3V AND 5V FIXED OR ADJUSTABLE
OUTPUT VOLTAGE (2V UP TO 5.2V)
120m INTERNAL ACTIVE SWITCH
LOW BATTERY VOLTAGE DETECTION
REVERSE BATTERY PROTECTION
1.1 Applications
ONE TO THREE CELL BATTERY DEVICES
PDA AND HAND HELD INSTRUMENTS
CELLULAR PHONES - DIGITAL CORDLESS
PHONE
PAGERS
GPS
DIGITAL CAMERAS
2 Description
The L6920 is a high efficiency step-up controller re-
quiring only three external components to realize the
conversion from the battery voltage to the selected
output voltage.
The start up is guaranteed at 1V and the device is op-
erating down to 0.6V.
Internal synchronous rectifier is implemented with a
120m
P-channel MOSFET and, in order to improve
the efficiency, a variable frequency control is imple-
mented.
1V HIGH EFFICIENCY SYNCRONOUS STEP UP CONVERTER
Figure 1. Application Circuit
L1
LX
8
OUT
1
FB
3
6
LBO
GND
SHDN
7
5
LBI
2
REF
4
V
CC
V
OUT
2.5V 3.3V
500mA
L6920D
C2
C3 C1
Fi
gure 1.
P
ac
k
age
Table 1. Order Codes
Part Number Package
L6920D TSSOP8 Tube
L6920DTR Tape & Reel
TSSOP8
Rev. 2
L6920
2/13
Table 1. Pin Description
Figure 2. Pin Connection (Top view)
Table 2. Absolute Maximum Ratings
Table 3. Thermal Data
Pin Name Function
1FB
Output voltage selector. Connect FB to GND for Vout=5V or to OUT for Vout=3.3V. Connect FB to an
external resistor divider for adjustable output voltage (from 2V to 5.2V) [see R4 and R5, fig. 7].
2 LBI Battery low voltage detector input. The internal threshold is set to 1.23V.
A resistor divider is needed to adjust the desired low battery threshold:
[see R1 and R2, fig. 7]
3
LBO
Battery low voltage detector output. If the voltage at the LBI pin drops below the internal
threshold typ. 1.23V, LBO goes low.
The
LBO is an open drain output and so a pull-up resistor (about 200K) has to be added for
correct output setting [see R3, fig. 7].
4 REF 1.23V reference voltage. Bypass this output to GND with a 100nF capacitor for filtering high
frequency noise. No capacitor is required for stability
5
SHDN
Shutdown pin. When pin 5 is below 0.2V the device is in shutdown, when pin 5 is above 0.6V the
device is operating.
6 GND Ground pin
7 LX Step-up inductor connection
8 OUT Power OUTPUT pin
Symbol Parameter Value Unit
V
ccmax
V
cc
to GND 6 V
LBI, SHDN, FB to GND 6 V
V
out max
Vout to GND 6 V
Symbol Parameter Value Unit
R
th j-amb
Thermal Resistance Junction to Ambient 250 °C/W
T
j
Maximum Junction Temperature 150 °C
V
LBI
1.23V= 1
R1
R2
------- -+
⎝⎠
⎛⎞
FB
LBI
REF
GND
LX
OUT1
3
2
4
6
5
7
8
TSSOP
8
LBO
SHDN
3/13
L6920
Table 4. Electrical Characteristcs
(V
in
= 2V, FB = GND, T
amb
= -40°C to 85°C and T
j
< 125°C unless otherwise specified)
Symbol Parameter Test Condition Min. Typ. Max. Unit
V
CC
SECTION
V
in
Minimum operating Input Voltage 0.6 V
V
in
Minimum Start Up Input Voltage 1 V
I
q
Quiescent Current I
l
=0 mA, FB = 1.4V, V
out
= 3.3V
LBI = SHDN = 2V, T
j
= T
amb
915µA
I
l
=0 mA, FB = 1.4V, V
out
= 5V
LBI = SHDN = 2V, T
j
= T
amb
11 18 µA
I
sd
Shut Down Current V
in
= 5V, I
l
=0 mA 0.1 1 µA
Irev Reverse battery current V
in
= -4V, T
j
= T
amb
0.1 2 µA
POWER SECTION
R
on-N
Active switch ON resistance 120 250 m
R
on-P
Synchronous switch ON
resistance
120 250 m
CONTROL SECTION
V
ou
t Output voltage FB = OUT, I
l
=0 mA 3.2 3.3 3.4 V
FB = GND, I
l
=0 mA 4.955.1V
Output voltage range External divider 2 5.2 V
V
LBI
LBI threshold 1.18 1.23 1.27 V
0°C < T
j
< 70°C 1.205 1.23 1.255 V
V
LBO
LBO logic LOW
I
sink
< 250µA 0.20.4V
I
lim
LX switch current limit 0.8 1 1.2 A
T
onmax
Maximum on time V
out
= 2V to 5.3V 3.75 5 6.25 µs
T
offmin
Minimum off time V
out
= 2V to 5.3V 0.75 1 1.25 µs
SHDN SHDN logic LOW
0.2 V
SHDN logic HIGH
0.6 V
V
ref
Reference Voltage 1.18 1.23 1.27 V

L6920D

Mfr. #:
Manufacturer:
STMicroelectronics
Description:
Switching Voltage Regulators 0.6 to 5.5V Step-Up
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
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