AIC AIC1650CN 3-cell, high-efficiency, inverting dc/dc converter Datasheet

AIC1650
3-Cell, High-Efficiency, Inverting DC/DC
Converter
FEATURES
4V to 20V Input Voltage Operation.
Adjustable Output Voltage up to -40V.
Low Quiescent Current at 100µA.
Pulse Frequency Modulation Maintains High
Efficiency (max. 90%).
100KHz to 320KHz Switching Frequency.
Power-Saving Shutdown Mode (8µA Typical).
High Efficiency with Low Cost External PNP
Bipolar Transistor.
APPLICATIONS
Negative LCD Contrast Bias for
1. Notebook & Palmtop Computers.
2. Pen-Based Data System.
3. Portable Data Collection Terminals.
4. Personal Digital Assistants.
Negative Voltage Supply.
DESCRIPTION
The AIC1650 is a high performance inverting
DC/DC converter, designed to drive an external
power switch to generate programmable negative voltages. In the particularly suitable LCD
bias contrast application, maximum efficiency of
90% can be achieved with low cost PNP bipolar
transistor drivers. 4V to 20V input operation
range allows the AIC1650 to be powered directly by the battery pack in most batteryoperated applications for greater efficiency.
Output voltage can be scaled to -40V or greater
by two external resistors. A pulse frequency
modulation scheme is employed to maintain
high efficiency conversion under wide input
voltage range. Quiescent current is
about
100µA and can be reduced to 8µA in shutdown
mode. Switching frequency being around
100KHz to 320KHz range, small size switching
components are ideal for battery powered portable equipments, like notebook and palmtop
computers.
TYPICAL APPLICATION CIRCUIT
VIN
+4V ~ 20V
100µF +
C1
VIN
CL
VREF
DHI
SHDN
DLOW
FB
5V
Q1
2N2907A
D1 1N5819
RB
1.5K~12K
GND
*L
150µH
AIC1650
0.047µF
R2
100K
C2
VOUT
-12V~ -40V
+
R1
1M
C4
100µF
C3
*
Sumida CD-54 SERIES
VOUT = -1.22V x R1/R2
10nF
Negative LCD Contrast Bias Power Supply
Analog Integrations Corporation
4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC
DS-1650-02 Dec 27, 00
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
1
AIC1650
ORDERING INFORMATION
AIC1650 XX
PACKAGE TYPE
N: PLASTIC DIP
S: SMALL OUTLINE
TEMPERATURE RANGE
C=0°C~+70°C
PIN CONFIGURATION
ORDER NUMBER
TOP VIEW
AIC1650CN
(PLASTIC DIP)
AIC1650CS
(PLASTIC SO)
VIN
1
8
VREF
2
7
DHI
SHDN
3
6
DLOW
4
5
GND
FB
CL
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
.................................................………….................................. 20V
SHDN Voltage .............................................…………….................................... 15V
Operating Temperature Range ..........................………........................... 0°C~ 70°C
Storage Temperature Range
..................................………................ -65°C~ 150°C
TEST CIRCUIT
ELECTRICAL CHARACTERISTICS
Refer to Typical Application Circuit.
fied.)
PARAMETER
TEST CONDITIONS
Input Voltage
(VIN=13V, Ta=25°°C, unless otherwise speci-
MIN.
TYP.
MAX.
UNIT
20
V
100
200
µA
1.22
1.28
V
4
Switch Off Current
VFB = -50mV
VREF Voltage
ISOURCE = 250µA
VREF Source Current
1.16
µA
250
DLOW “ON Resistance”
15
Ω
DHI “ON Resistance”
10
Ω
CL Threshold
50
70
90
mV
Shutdown Threshold
0.8
1.5
2.4
V
8
20
µA
Shutdown Mode Current
V SHDN =0V
2
AIC1650
TYPICAL PERFORMANCE CHARACTERISTICS
20
Shutdown Current (µA)
Source Current (µA)
Shutdown Current vs VIN
VREF Source Current vs VIN
350
300
250
200
150
4
8
12
16
15
10
5
0
20
4
VIN (V)
8
10
12
14
16
18
20
Frequency vs VIN Voltage
330
280
Frequency (kHz)
90
Duty Cycle (%)
6
VIN (V)
Duty Cycle vs VIN Voltage
100
(Ta=25°°C)
80
Ta=70°C
70
Ta=0°C
Ta=0°C
230
Ta=25°C
180
Ta=70°C
130
60
Ta=25°C
50
80
4
8
12
16
20
4
8
12
VIN (V)
16
20
VIN (V)
BLOCK DIAGRAM
VIN
VREF
SHDN
FB
+
2
PFM
OSCILLATOR
3
1.22V
REFERENCE
VOLTAGE
4
V IN
CURRENT LIMIT
COMPARATOR
1
LATCH
V IN
OUTPUT DRIVER
+
-
70mV
8
7
6
5
ERROR COMPARATOR
CL
DHI
DLOW
GND
3
AIC1650
PIN DESCRIPTIONS
PIN 1: VIN
PIN 6: DLOW - Driver sinking output. Connected
to DHI when using an external
P-channel MOSFET. When using an external PNP bipolar
transistor, connect a resistor RB
from this pin to DHI. RB value
depends on VIN, inductor and
PNP bipolar transistor. By adjusting the RB value, efficiency
can be optimized.
- 4V to 20V input supply voltage.
PIN 2: VREF - 1.22V reference output. Bypass
with a 0.047µF capacitor to GND.
Sourcing capability is guaranteed to be greater than 250µA.
PIN 3: SHDN- Logic input to shutdown the chip.
>1.5V = normal operation,
GND = shutdown
In shutdown mode DLOW and
DHI pins are at high level.
PIN 4: FB
- Feedback signal input to sense
ground. Connecting a resistor
R1 to VOUT and a resistor R2 to
VREF pin yields the output voltage:
PIN 7: DHI
- Driver sourcing output. Connect
to gate of the external P-channel
MOSFET or base of the PNP bipolar transistor.
PIN 8: CL
- Current-limit input. This pin
clamps the switch peak current
to prevent over-current damage
to the external switch.
VOUT = -(R1/R2 ) x VREF
PIN 5: GND - Power ground.
APPLICATION INFORMATIONS
Max. Output Power vs VIN
The typical application circuit generates an adjustable
1.8
negative voltage for contrast bias of LCD displays.
Typical Application Circuit
1.6
100µH
1.4
Max. Output Power (W)
Efficiency and output power can be optimized by us-
120µH
ing appropriate inductor and switch. The following
1.2
150µH
1
220µH
0.6
270µH
0.4
timal component values:
L
PNP :
Inductor Value
4
6
8
10
12
VIN (V)
14
V IN
I OUT × V OUT
= (11.1 − 0.15 × V IN) ×
300µH
330µH
0.2
0
formulas provide a guideline for determining the op-
180µH
0.8
16
18
20
V CEO > V IN + V OUT
I C,MAX ≥ 200 ×
V CE < 0. 4V at I
and β = 10
I OUT
V IN
C
= 200 ×
IOUT
V IN
RB ≅ 3 x L x (VIN - 0.8)
where, units: VIN & VOUT in V, IOUT in A, L in µH,
RB in Ω
4
AIC1650
APPLICATION EXAMPLES
Efficiency vs Load Current
95
Efficiency vs VIN
95
VOUT = -15V
L
=220µH
VOUT =-15V
IOUT =-10mA
VIN=13V
L=300µH
90
Efficiency (%)
Efficiency (%)
90
VIN =8V
85
VIN=18V
L=220µH
L=150µH
85
80
75
0
5
10
15
20
25
80
30
4
8
6
90
20
L=220µH
Efficiency (%)
Efficiency (%)
18
VOUT =-22V
IOUT =-10mA
L=300µH
VIN=13V
VIN=8V
16
Efficiency vs VIN
95
VOUT =-22V
L
=220µH
90
14
VIN (V)
Efficiency vs Load Current
95
12
10
Load Current (mA)
VIN=18V
85
L=150µH
85
80
75
0
5
10
15
20
25
80
30
4
6
8
10
Efficiency vs Load Current
90
VIN=8V
Efficiency (%)
80
5
10
15
18
20
L=220µH
90
85
0
16
20
Load Current (mA)
VOUT = -30V
IOUT = -10mA
L=300µH
VIN=13V
VIN=18V
75
14
Efficiency vs VIN
95
95
VOUT = -30V
L
= 220µH
12
VIN (V)
Load Current (mA)
Efficiency (%)
25
30
L=150µH
85
80
4
6
8
10
12
14
16
18
20
VIN (V)
5
AIC1650
PHYSICAL DIMENSIONS
8 LEAD PLASTIC SO (unit: mm)
D
SYMBOL
MIN
MAX
A
1.35
1.75
A1
0.10
0.25
B
0.33
0.51
C
0.19
0.25
D
4.80
5.00
E
3.80
4.00
H
E
e
e
A
C
A1
B
1.27(TYP)
H
5.80
6.20
L
0.40
1.27
L
8 LEAD PLASTIC DIP (unit: mm)
D
E1
E
A2
A1
C
L
eB
b
e
SYMBOL
MIN
MAX
A1
0.381
—
A2
2.92
4.96
b
0.35
0.56
C
0.20
0.36
D
9.01
10.16
E
7.62
8.26
E1
6.09
7.12
e
2.54 (TYP)
eB
—
10.92
L
2.92
3.81
6
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