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HT7936A/HT7936B White LED Step-up Charge Pump Converter
Features
* Input voltage range: 2.8V to VOUT * Driving current: 110mA (HT7936A), * Oscillator frequency: 1MHz * Soft start function, current limit,
150mA (HT7936B)
* Fixed output voltage: 5V (HT7936A),
short circuit protection
* Small outline SOT23-6 package
4.5V (HT7936B)
Applications
* Cellular phones * PDAs * DSCs * Handheld devices * White LED display backlighting
General Description
The HT7936A and HT7936B are charge-pump type DC-DC step-up converter devices, which can generate regulated fixed output voltages of 5.0V and 4.5V. Their high degree of functional integration requires only the addition of three external capacitors, namely a flying capacitor and an input and output capacitor, to implement a full step-up conversion function. The devices have the additional benefit of an integrated soft start function to reduce the level of in-rush current during device power on. The operating voltage range is from 2.8V to the full output voltage value, VOUT. To meet the demands of todays power sensitive applications, the devices, have a very low standby current value as well as the extra safety features of current limit and short circuit protection. This range of device features, supplied in 6-pin SOT-23-6 package type, will ensure that these device will find excellent use in a wide range of DC-DC step-up converter applications.
Selection Table
Part No. HT7936A HT7936B Output Voltage 5.0V 4.5V Tolerance 4% 4% Package SOT23-6 SOT23-6
Rev 1.00
1
December 28, 2009
HT7936A/HT7936B
Block Diagram
C+ V IN C-
M4
M1
M2
M3
VOUT
S h o r t C ir c u it P r o te c io n
C o n tro l GND
EN
VREF 1M H z O SC
N o te : D u r in g o p e r a tio n th e fo llo w in g s e q u e n c e o c c u r s : 1 . M 1 , M 3 O n / M 2 , M 4 O ff 2 . M 2 , M 4 O n / M 1 , M 3 O ff
Pin Assignment
C+ 6 V IN 5 C4
T o p V ie w
1 VOUT
2 GND
3 EN
Pin Description
Pin No. 1 2 Pin Name VOUT GND Description Regulated Output Voltage. VOUT should be bypassed with a 1mF to 10mF low ESR ceramic capacitor placed as close as possible to the pin for best performance. Ground. This pin is the voltage reference for the regulator output voltage. Device On/Off Control 1: Enable 0: Disable Pin must not be left floating. Capacitor Negative Pin. Flying capacitor negative terminal. Input Supply Voltage. VIN should be bypassed with a 1mF to 10mF low ESR ceramic capacitor. Capacitor Positive Pin. Flying capacitor positive terminal.
3
EN
4 5 6
CVIN C+
Rev 1.00
2
December 28, 2009
HT7936A/HT7936B
Absolute Maximum Ratings
Input Supply Voltage..................................................6V Operating Temperature Range ...............-40C to 85C Other Pins Voltage ....................................................6V Maximum Junction Temperature..........................125C
Note: These are stress ratings only. Stresses exceeding the range specified under Absolute Maximum Ratings may cause substantial damage to the device. Functional operation of this device at other conditions beyond those listed in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability.
Electrical Characteristics
Symbol VIN Parameter Input Supply Voltage
VIN=VEN=3.7V, CIN=CPUMP=COUT=1mF, Ta=25C, unless otherwise specified. Test Conditions HT7936A HT7936B Min. 2.8 2.8 4.80 4.32 3/4 3/4 110 150 3/4 3/4 0.8 1.5 3/4 3/4 3/4 3/4 Typ. 3/4 3/4 3/4 3/4 0.1 2.0 3/4 3/4 60 370 1.0 3/4 3/4 30 80 80 Max. 5.0 4.5 5.20 4.68 1.0 4.0 3/4 3/4 90 500 1.3 3/4 0.4 3/4 3/4 3/4 Unit V V V V mA mA mA mA mA mA MHz V V mV % %
VOUT ISHDN IQ IO ISHORT ILIMIT fOSC VENH VENL VRIPPLE h Note:
Output Voltage Shutdown Current Operation Current Output Current
HT7936A, VIN>3.2V, IO110mA HT7936B, VIN>3.2V, IO140mA VEN=0 3/4 HT7936A HT7936B
Short Circuit Current Current Limit Switching Frequency EN Pin Voltage High EN Pin Voltage Low Output Ripple Voltage Efficiency
3/4 3/4 3/4 2.8V VIN 5.0V 2.8V VIN 5.0V IO=60mA, COUT=2.2mF HT7936A, VIN=3.0V, IO=50mA HT7936B, VIN=2.8V, IO=70mA
Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. The guaranteed specifications apply only for the test conditions listed. Specifications are production tested at Ta=25C. Specifications over -40C to +85C operating temperature range are assured by design.
Rev 1.00
3
December 28, 2009
HT7936A/HT7936B
Functional Description
These DC-DC step-up converters can generate fixed level output voltages higher than their input supply voltage. Operation Utilising a charge pump method with three external capacitors to store and transfer energy, the devices can transfer electrical energy from input to output at different voltage levels. Since the capacitors are not able to change their voltage level abruptly, the VOUT/VIN voltage ratio of VOUT over VIN is limited within a fixed range. Capacitive voltage conversion is obtained by the periodic switching of a capacitor. It first charges the capacitor CPUMP by connecting it across a voltage source after which it is connected to the output. Referring to Figure.1, during the on state of the internal clock, M1 and M3 are closed, M2 and M4 are opened, which charges CPUMP to a VIN level. During the off state of the internal clock, M2 and M4 are closed, M1 and M3 are opened, which transfers the energy to the output. The output voltage is therefore VIN plus VCPUMP, which is in effect equal to 2VIN.
V
IN
Capacitor Selection Careful selection of the three external capacitors CIN, COUT and CPUMP is important because they will affect ramp-up time, output ripple and transient performance. Optimum performance will be obtained when low ESR (<100mW) ceramic capacitors are used for CIN and COUT and CPUMP. In general, a low ESR may be defined as less than 100mW. In all cases, X7R or X5R dielectrics are recommended. For certain applications, low ESR Tantalum capacitors may be substituted, however optimum output ripple performance may not be attainable. Aluminum electrolytic capacitors are not recommended for use with these devices due to their inherent high ESR characteristics. In general the CIN, COUT and CPUMP capacitors may range from 1mF to 10mF for heavy output load conditions. If the CPUMP capacitor is increased, then COUT should also be increased by the same ratio to minimise output ripple. Lowering the values of CIN, COUT and CPUMP may decrease the ramp-up time of VOUT, but it will inversely increase the output ripple. Efficiency The efficiency of the charge pump regulator varies with the output voltage type, the applied input voltage, the load current and the internal operation mode of the device. The approximate device efficiency is given by:
C
IN
M1 C M2
PUMP
M4 C M3
V
OUT
OUT
Figure.1 Shutdown The devices can be shutdown by setting the EN input pin to a low level. In the shutdown mode, the output is disconnected from the input. The input current will reduce to an extremely low level as most of the internal circuitry is inactive. As the EN pin is a high impedance input, it must not be allowed to float. Short Circuit Protection The devices contain integrated short circuit protection circuits with current limiting protection. During a short circuit condition, the output current is automatically limited to a typical value of approximately 60mA. If the fault does not clear itself, the protect operation will repeat continuously. This protection feature allows the devices to operate indefinitely under short circuit conditions without damaging the device.
Due to internal switching losses and IC quiescent current consumption, the actual measured efficiency will decrease.
Rev 1.00
4
December 28, 2009
HT7936A/HT7936B
Typical Operating Characteristics
For HT7936A, CIN=COUT=2.2mF, CPUMP=0.22mF, Ta=25C, unless otherwise specified
HT7936A Output Voltage vs. Output Current 5.1 5.0
Output Voltage(V)
4.9 4.8 4.7 4.6 4.5 4.4 4.3 10 20 30 40 50 60 70 80 90 100 110 Output Current(mA)
VIN=2.8V VIN=3V VIN=3.2V VIN=3.7V VIN=4.2V VIN=5V
HT7936A Operation Current vs. Input Voltage 2.2
Quiescent Current(mA)
2.1 2.0 1.9 1.8 1.7 1.6 1.5 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.8 5.0 Input Voltage(V) IQ IQ
Rev 1.00
5
December 28, 2009
HT7936A/HT7936B
HT7936A Output Voltage vs. Supply Voltage 5.1 5.0
Output Voltage(V)
IO=10mA IO=20mA IO=30mA IO=40mA IO=50mA IO=60mA IO=70mA IO=80mA IO=90mA IO=100mA 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.8 5.0 IO=110mA Supply Voltage(V)
4.9 4.8 4.7 4.6 4.5 4.4 4.3
HT7936A Efficiency vs. Output Current 90% 85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 10 20 30 40 50 60 70 80 90 100 110 Output Current(mA)
VIN=2.8V VIN=3V VIN=3.2V VIN=3.7V VIN=4.2V VIN=5V
Efficiency
HT7936A Efficiency vs. Input Voltage 90% 85% 80% 75% 70% 65% 60% 55% 50% 45% 40% 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.8 5.0 Input Voltage(V)
IO=10mA IO=20mA IO=30mA IO=40mA IO=50mA IO=60mA IO=70mA IO=80mA IO=90mA IO=100mA IO=110mA
Rev 1.00
Efficiency
6
December 28, 2009
HT7936A/HT7936B
For HT7936B, CIN=COUT=2.2mF, CPUMP=0.22mF, Ta=25C, unless otherwise specified
HT7936B Output Voltage vs. Output Current 4.6 4.5
Output Voltage(V)
4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 10 25 40 55 70 85 100 115 130 145 Output Current(mA) VIN=2.8V VIN=3V VIN=3.2V VIN=3.7V VIN=4.5V
HT7936B Operation Current vs. Input Voltage 2.2
Quiescent Current(mA)
2.1 2.0 1.9 1.8 1.7 1.6 1.5 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 Input Voltage(V) IQ IQ
Rev 1.00
7
December 28, 2009
HT7936A/HT7936B
HT7936B Output Voltage vs. Supply Voltage IO=10mA 4.6 4.5
Output Voltage(V)
IO=20mA IO=30mA IO=40mA IO=50mA IO=60mA IO=70mA IO=80mA IO=90mA IO=100mA IO=110mA IO=120mA 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 IO=130mA IO=140mA IO=150mA
4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 Supply Voltage(V)
HT7936B Efficiency vs. Output Current 85% 80% 75%
Efficiency
70% 65% 60% 55% 50% 45% 40% 10 25 40 55 70 85 100 115 130 145 Output Current(mA)
VIN=2.8V VIN=3V VIN=3.2V VIN=3.7V VIN=4.5V
HT7936B Efficiency vs. Input Voltage IO=10mA 85% 80% 75%
Efficiency
IO=20mA IO=30mA IO=40mA IO=50mA IO=60mA IO=70mA IO=80mA IO=90mA IO=100mA IO=110mA IO=120mA 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 IO=130mA IO=140mA IO=150mA
70% 65% 60% 55% 50% 45% 40% Input Voltage(V)
Rev 1.00
8
December 28, 2009
HT7936A/HT7936B
Inrush Current
HT7936A VIN=2.8V, CIN=COUT=2.2mF, CPUMP=0.22mF
HT7936B VIN=2.8V, CIN=COUT=2.2mF, CPUMP=0.22mF
HT7936A VIN=5.0V, CIN=COUT=2.2mF, CPUMP=0.22mF
HT7936B VIN=4.5V, CIN=COUT=2.2mF, CPUMP=0.22mF
Rev 1.00
9
December 28, 2009
HT7936A/HT7936B
Normal Operation
HT7936A VIN=2.8V, CIN=COUT=2.2mF, CPUMP=0.22mF
HT7936B VIN=2.8V, CIN=COUT=2.2mF, CPUMP=0.22mF
HT7936A VIN=5.0V, CIN=COUT=2.2mF, CPUMP=0.22mF
HT7936B VIN=4.5V, CIN=COUT=2.2mF, CPUMP=0.22mF
Rev 1.00
10
December 28, 2009
HT7936A/HT7936B
Dimming Operation
HT7936A, Refer to Figure.2
V IN C+ V 3 .7 V
IN
EN 06%'!$) VOUT GND COU 1mF
T
C
1mF
IN
C
1mF
PUMP
C-
R1 100W LED 3V
R2 100W LED
R3 100W LED
PW M 100H z~15kH z
0V
Q1
Figure.2
Rev 1.00
11
December 28, 2009
HT7936A/HT7936B
HT7936A, Refer to Figure.3
PW M V IN C+ V 3 .7 V
IN
500Hz 3V 0V
EN 06%'!$) VOUT GND 1mF C
OUT
C
IN
1mF
C
PUMP
1mF
C-
R1 100W LED
R2 100W LED
R3 100W LED
Figure.3
Application Circuits
2 .8 V to V
OUT
V IN C+ V
IN
C
IN
C
PUMP
C-
EN 06%'!$) 06%'!$* VOUT R GND C
LED
OUT
LED
LED
N o te : C
IN
=C
PUMP
=C
OUT
= 1 m F (T A IY O
YUDEN
JM K 107B J105K A )
Rev 1.00
12
December 28, 2009
HT7936A/HT7936B
Package Information
6-pin SOT23-6 Outline Dimensions
D
C
L
E
H
e
A2 b A1
A
Symbol A A1 A2 b C D E e H L q
Dimensions in mm Min. 1.0 3/4 0.7 0.35 0.10 2.7 1.4 3/4 2.6 0.37 1 Nom. 3/4 3/4 3/4 3/4 3/4 3/4 3/4 1.9 3/4 3/4 3/4 Max. 1.3 0.1 0.9 0.50 0.25 3.1 1.8 3/4 3.0 3/4 9
Rev 1.00
13
q
December 28, 2009
HT7936A/HT7936B
Product Tape and Reel Specifications
Reel Dimensions
T2 D
A
B
C
T1
SOT23-6 Symbol A B C D T1 T2 Description Reel Outer Diameter Reel Inner Diameter Spindle Hole Diameter Key Slit Width Space Between Flange Reel Thickness Dimensions in mm 178.01.0 62.01.0 13.00.2 2.500.25 8.4 11.4
+1.5/-0.0 +1.5/-0.0
Rev 1.00
14
December 28, 2009
HT7936A/HT7936B
Carrier Tape Dimensions
D
E F
P0
P1
t
W C
B0
D1
P A0
K0
R e e l H o le IC M a r k in g
SOT23-6 Symbol W P E F D D1 P0 P1 A0 B0 K0 t C Description Carrier Tape Width Cavity Pitch Perforation Position Cavity to Perforation (Width Direction) Perforation Diameter Cavity Hole Diameter Perforation Pitch Cavity to Perforation (Length Direction) Cavity Length Cavity Width Cavity Depth Carrier Tape Thickness Cover Tape Width Dimensions in mm 8.00.3 4.00.1 1.750.1 3.500.05 1.5 1.5
+0.1/-0.0 +0.1/-0.0
4.00.1 2.000.05 3.150.1 3.20.1 1.40.1 0.200.03 5.30.1
Rev 1.00
15
December 28, 2009
HT7936A/HT7936B
Holtek Semiconductor Inc. (Headquarters) No.3, Creation Rd. II, Science Park, Hsinchu, Taiwan Tel: 886-3-563-1999 Fax: 886-3-563-1189 http://www.holtek.com.tw Holtek Semiconductor Inc. (Taipei Sales Office) 4F-2, No. 3-2, YuanQu St., Nankang Software Park, Taipei 115, Taiwan Tel: 886-2-2655-7070 Fax: 886-2-2655-7373 Fax: 886-2-2655-7383 (International sales hotline) Holtek Semiconductor Inc. (Shenzhen Sales Office) 5F, Unit A, Productivity Building, No.5 Gaoxin M 2nd Road, Nanshan District, Shenzhen, China 518057 Tel: 86-755-8616-9908, 86-755-8616-9308 Fax: 86-755-8616-9722 Holtek Semiconductor (USA), Inc. (North America Sales Office) 46729 Fremont Blvd., Fremont, CA 94538, USA Tel: 1-510-252-9880 Fax: 1-510-252-9885 http://www.holtek.com
Copyright O 2009 by HOLTEK SEMICONDUCTOR INC. The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are used solely for the purpose of illustration and Holtek makes no warranty or representation that such applications will be suitable without further modification, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. Holteks products are not authorized for use as critical components in life support devices or systems. Holtek reserves the right to alter its products without prior notification. For the most up-to-date information, please visit our web site at http://www.holtek.com.tw.
Rev 1.00
16
December 28, 2009

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