ZD3202 Low Noise Charge Pump Based White LED Driver
Zywyn
Features
·
·
·
·
·
·
·
·
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Low Noise, Constant Frequency Operation
High efficiency 1.5X Charge pump
High Output Current: Up To 125mA
Regulated Output Voltage or Current
Vin range: 2.7V to 4.5V
No Inductors
1.5MHz Switching Frequency
Icc < 1μA in Shutdown
Available in 10-Pin MSOP Green Package
ZD3202
Low Noise, High Efficiency
Charge-Pump Based DC/DC Converter
General Description
The ZD3202 is a low noise, constant frequency, regulated
DC/DC converter that uses 1.5X charge pump to increase
efficiency in white LED applications. The part can be used to
produce a regulated voltage or current of up to 125mA from a
2.7V to 4.5V input. Low external parts count make the ZD3202
ideally suited for small, battery-powered applications.
An internal 2-bit DAC allows LED current to be adjusted for
LED brightness control. The ZD3202 also has thermal shut-
down protection and can survive a continuous short-circuit
from Vout to GND. High switching frequency enables the use
of small external capacitors. A low current shutdown feature
disconnects the load from Vin and reduces quiescent current
to less than 1mA.
The ZD3202 is available in a 10-pin MSOP package.
Applications
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White LED Backlighting
Programmable Boost Current Source
Cellular Phones
MP3 Players, Portable Media Players
Digital Cameras Modules Display Backlite
Battery Powered LCD Displays and Modules
Ordering Information
Part Number
ZD3202LEU
ZD3202EVB
Temperature Range
–40°C to +85°C
n/a
Package Type
10-pin MSOP
Evaluation Board
Pin Configuration
Please contact the factory for pricing and availabiliy on a Tape-on-Reel
option.
Typical Application
10-Pin MSOP
Current Setting Logic Inputs Truth Table
D1 D0
Mode
0 0
Shutdown
0 1
40mA
1 0
80mA
1 1
125mA
Based on R
SET
=36Ω
Specifications subject to change without notice
Zywyn Corporation • Tel (408) 733-3225 • Fax (408) 733-3206 • Email sales@zywyn.com • www.zywyn.com
June 2010
rev. 1.4
Zywyn Corporation
Absolute Maximum Ratings
These are stress ratings only and functional operation of the
device at these ratings or any other above those indicated
in the operation sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended
periods of time may affect reliability.
V
IN
, V
OUT
to GND ........................................ –0.3V to +6.0V
D0, D1 ...................................................-0.3V to Vin + 0.3V
V
OUT
Short-Circuit Duration................................. Indefinite
I
OUT
(Note 1).............................................................150mA
Operation Temperature Range (Note 2) ........ -40 to +85°C
Maximum Junction Temperature ........................ +150°C
Storage Temperature Range ........................ -65 to +150°C
Lead Temperature (Soldering 10 sec) .......................300°C
Power Dissipation Per Package
10-pin MSOP Thermal Resistance (θ
JA
)
....................
157ºC/W
Note 1: Based on long-term current density limitations
Note 2: The ZD3202 is guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over
the -40°C to 85°C operating temperature range are by
design, characterization and correlation with statistical
process controls.
ZD3202
Storage Considerations
Storage in a low humidity environment is preferred. Large
high density plastic packages are moisture sensitive and
should be stored in Dry Vapor Barrier Bags. Prior to usage,
the parts should remain bagged and stored below 40°C and
60%RH. If the parts are removed from the bag, they should
be used within 168 hours or stored in an environment at or
below 20%RH. If the above conditions cannot be followed,
the parts should be baked for 12 hours at 125°C in order
to remove moisture prior to soldering. Zywyn ships prod-
uct in Dry Vapor Barrier Bags with a humidity indicator card
and desiccant pack. The humidity indicator should be below
30%RH. The MSL of this product is 3.
The information furnished by Zywyn has been carefully
reviewed for accuracy and reliability. Its application or use,
however, is solely the responsibility of the user. No responsibil-
ity of the use of this information become part of the terms and
conditions of any subsequent sales agreement with Zywyn.
Specifications are subject to change without the responsibility
for any infringement of patents or other rights of third parties
which may result from its use. No license or proprietary rights
are granted by implication or otherwise under any patent or
patent rights of Zywyn Corporation.
Zywyn
Specifications subject to change without notice
2
June 2010
rev. 1.4
Zywyn Corporation
Electrical Characteristics
Specifications are at T
A
= 25
o
C, V
IN
= 3.3V, R
SET
=36Ω, unless otherwise noted.
Parameter
Input Power Supply
V
IN
Operating Voltage
I
CC
Operating Current
I
SHDNB
Shutdown Current
Feedback Pin Set Points
{D0,D1}={1,0} V
FB
Setting
{D0, D1}={0,1} V
FB
Setting
{D0, D1}={1,1} V
FB
Setting
I
FB
Charge Pump
R
OL
Open Loop Output Impedance
(1.5V
IN
- V
OUT
) / I
OUT
V
OUT
Load Regulation (V
OUT
/ I
OUT
)
CLK Frequency
Data Input, D0, D1
High Level Input Voltage (V
IH
)
Low Level Input Voltage (V
IL
)
Input Current (I
IH
)
Input Current (I
IL
)
1.4
D1 = D0 = V
IN
D1 = D0 = 0V
-1
-1
0.4
1
1
V
IN
= 3.3V, V
OUT
= 4.4V, V
FB
= 0
I
OUT
= 10mA to 90mA, V
FB
/ V
OUT
= 1
6
0.35
1.5
D1 = 0, D0 = 1, IOUT = 0mA, VIN = 3.6V
D1 = 1, D0 = 0, IOUT = 0mA, VIN = 3.6V
D1 = 1, D0 = 1, IOUT = 0mA, VIN = 3.6V
V
FB
= 0.8V
185
430
540
-50
220
480
610
2.7
I
OUT
= 0mA, V
IN
= D0 = D1 = 3.6V
V
OUT
= 0V
2.5
4.5
5
1
Condition
Min
Typ
ZD3202
Max
Units
V
mA
μA
mV
mV
mV
nA
250
550
670
50
Ω
mV/mA
MHz
V
V
μA
μA
Zywyn
Specifications subject to change without notice
3
June 2010
rev. 1.4
Zywyn Corporation
Block Diagram
ZD3202
1μF
1μF
C1N
C1P
C2P
C2N
2.7V to 4.5V
VIN
VCP
0.1μF
2 Phase
1.5X Fractional
Charge Pump
VOUT=1.5(VCP)
ILED=VFB/RSET
1μF
White
LED
(External
Components)
FB
VOUT
CLK
Additional
White LED
Parallel Strings
VDD VIP
OUT
IBN
VIN
GND
VIN
Error Amp
RSET
36
Ω
VSET
D0
1.5MHz
OSCILLATOR
Bias
Band Gap
Reference
2 bit DAC
D1
Pin Description
Pin Number
1, 10
2
3
4
5
6, 7, 8, 9
Pin Name
D1, D0
FB
V
OUT
VIN
GND
C2
-
, C1
-
, C1
+
, C2
+
Pin Function
Control Inputs. D0 and D1 determine the Set Point Voltage of the FB pin
(see Table 1)
FB is the Feedback Input for the regulation control loop.
V
OUT
is the Output of the Charge Pump. A low impedance 1μF X5R or X7R
ceramic capacitor is required from V
OUT
to GND.
Input Supply Voltage. VIN should be bypassed with a 1μF to 4.7μF low
impedance ceramic capacitor.
Ground for the Charge Pump and Control Circuitry. This pin should be
connected directly to a low impedance ground plane.
Charge Pump Flying Capacitor Pins. 1μF X5R or X7R ceramic capacitor
should be connected from C1
+
to C1
-
and from C2
+
to C2
-
.
Zywyn
Specifications subject to change without notice
4
June 2010
rev. 1.4
Zywyn Corporation
Circuit Description
The ZD3202 uses a state-of-the-art switched capacitor, frac-
tional conversion, charge pump to boost V
OUT
by as much as
50% above the input voltage. The charge pump switches are
driven by a two-phase, non-overlapping clock that assures
low EMI designs. The two-phase clock alternately charges
the flying capacitors and boosts the output voltage at a free
running frequency of 1.5MHz (typ).
Adjustable, Regulated Output
Regulation is provided by a feedback loop from the FB pin to
the charge pump modulator, resulting in stable output voltages
over the devices wide operating range. The regulated output
can be adjusted with the control pins, D0 and D1. The ZD3202
integrates a digital-to-analog converter to allow dynamic,digital
control of the regulated voltage. Table 1 shows the feedback
Set Point Voltage as a function of D0 and D1.
D1
0
0
1
1
D0
0
1
0
1
Feedback Set Point Voltage Output (R
SET
=36Ω)
0V
0.22V
0.48V
0.61V
Shutdown
40mA
80mA
125mA
ZD3202
Voltage or Current Programming of the ZD3202
The ZD3202 is configurable to regulate either voltage or cur-
rent. In white LED applications, the ratio of the feedback set
point and a sense resistor controls the current through the
white LED, as shown in Figure 1. The remaining white LEDs
are driven to a similar level by means of ballast resistors in
series with each similar white LED.
μF
Figure 1 Current Control Mode
This configuration requires the largest amount of output
capacitance to maintain stability, due to the high loop gain
caused by relativity low impedance of the white LED as
compared to the sense resistor.
In constant voltage applications. The output voltage is set
by the ratio of two resistors and the feedback set point, as
shown in Figure 2. V
OUT
= set point voltage * (1 + (R1/R2)).
The closed-loop output resistance is impacted by the resis-
tor ratio R1:R2, the higher the ratio, the higher the output
resistance. The output resistance is 0.35Ω with a nominal
gain of 1. Typically the total resistance of the voltage divider,
R1:R2, will be in the range of several KΩ to 1MΩ.
Table 1. Feedback Control Voltage Settings
Controlled Power-Down
The ZD3202 has a low-power shutdown mode controlled by
the control pins, D0 and D1. When both control pins are held
at a low logic level, the ZD3202 enters power down mode and
draws only leakage current from the V
IN
supply. All internal
circuitry is disabled and V
OUT
is disconnected from V
IN
. D0
and D1 control inputs are high impedance CMOS inputs and
should not be left floating. Ensure that they are always driven
with valid logic levels.
Shutdown Current
When the ZD3202 is placed in shutdown mode and while
the V
OUT
is still at a positive voltage, regulators feedback
circuit will draw 5uA of current. To minimize the current draw,
a bleed resistor of 10kΩ to 100kΩ can be used to draw down
V
OUT
during shutdown.
Short-Circuit/Thermal Protection
The ZD3202 has integrated short-circuit current limiting
circuitry designed to protect the device. Thermal protection
circuitry has also been integrated. These protection circuits
allow for robust designs during manufacturing and industrial,
as well as consumer environments. The current limit is set
to approximatley 250mA and the thermal protection will shut
down the charge pump when the die temperature reaches
approximately 160°C. The charge pump will be re-started
when the die temperature reaches approximately 155°C. The
ZD3202 will continue to cycle, without latchup or damage,
until the fault is corrected.
μF
Figure 2. Voltage Control Mode
Zywyn
Specifications subject to change without notice
5
June 2010
rev. 1.4
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