DC-DC Converter AMOLED PMIC HT8837J

HT8837J is a triple DC-DC converter designed to drive AMOLED display panel requiring 3 supply rails.
It integrates an 200mA step-up converter VPOS, an 200mA inverting converter VNEG and an 20mA auxiliary LDO AVDD. The device is particularly suitable for battery operated products, in which the major concern is the overall system efficiency. The digital control allows programming the VNEG in digital steps. Excellent line and load regulation, soft start with controlled inrush current limit, thermal shutdown and short circuit protection are also integrated.

1. Specifications

VIN=3.7V,CTRL=3.7V,EN=3.7V、VPOS=+4.6V、VNEG=-2.2V、AVDD=+3.3V, typical value at TA = 25°C (unless otherwise specified).

Symbol Parameters Condition Min. Typ. Max. Unit
General
VIN Power Supply Input Voltage 2.9 3.7 4.5 V
Temp Operating Temperature -40 25 85
ISD Shutdown Current CTRL=GND EN=GND 1 µA
VUVLO Undervoltage Lockout Threshold VIN Falling 2.1 V
VIN Rising 2.3
Logic Signal (CTRL)
VH High Threshold VIN=2.9 to 4.5V 1.2 V
VL Low Threshold 0.4
RDOWN Pull-Down Resistance 300 kΩ
Boost Converter (VPOS)
VPOS Positive Output Voltage 4.6 V
Positive Output Voltage
Variation
25°C≤TA≤ 85°C
No load
-0.5 0.5 %
–30°C≤TA≤ 85°C
No load
-0.8 0.8
RDS(on)1A Switch On-Resistance ISWP1=200mA 200 mΩ
RDS(on)1B Rectifier On-Resistance 600
fSW1 Switching Frequency IVPOS=200mA 1.5 MHz
ISW1 Switch Current Limit Inductor valley current 1 A
IO1MAX Maximum Output Current VIN=2.9V to 4.5V 200 mA
RDCHG1 Discharge Resistance CTRL=GND,ISWP1=1mA 30
Inverting Converter (VNEG)
VNEG Output Voltage Default -2.2 V
Output Voltage Range -1.4 -4.4
Output Voltage Accuracy 25°C≤TA≤ 85℃ No load -50 50 mV
–30°C≤TA≤ 85℃ No load -60 60
RDS(on)2A SWN MOSFET On-Resistance ISWN=200mA 200 mΩ
RDS(on)2B SWN Rectifier On-Resistance 300

2. Product Features

  • Operating Input Voltage Range from: 2.9V to 4.5V.
  • Boost Converter (VPOS).
(1) 4.6V Output Voltage;
(2) 200mA Output Current;
(3) 0.5% Accuracy (25°C to 85°C);
  • Inverting Converter (VNEG).
(1) -1.4V to -4.4V Programmable Output Voltage: (-2.2V Default);
(2) 200 mA Output Current;
  • LDO (AVDD).
(1) 3.3V default or lower of Vin;
(2) 20mA output current;
  • Efficiency > 90%.
  • Excellent Line and Load Regulation.
  • Short Circuit Protection.
  • Thermal shutdown.

3. Typical Application Circuit Diagram

Typical Application Circuit Diagram of Hotchip HT8837J

4. Pin Diagram and Functional Description

Hotchip chip HT8837J DFN12L

Pin Name Pin Number Functional Description
SWP 1 Boost Converter (VPOS) Switch Pin
PGND 2 Boost Converter (VPOS) Power Ground
VPOS 3 Boost Converter (VPOS) Output
EN 4 AVDD Enable pin
GND 5 Analog Ground
TEST 6 Reserved for device testing, Not Connected
CTRL 7 Boost Converter (VPOS) and VNEG Enable/Program Pin
AVDD 8 3.3V AVDD
VNEG 9 Inverting converter VNEG Output
SWN 10 Inverting converter VNEG Switch Pin
VIN 11 Power Supply
VIN 12 Power Supply
EPAD Connect this pad to GND and PGND

5. Features

  • Boost Converter (VPOS).
  • Inverting Converter (VNEG).
  • Soft Start and Start-up Sequence.
  • LDO (AVDD).
  • VPOS and VNEG Enable (CTRL).
  • Under-voltage Lockout.
  • Short Circuit Protection.
  • Output Discharge During Shut Down.
  • Device Functional Modes.
  • Typical Performances.
Scroll to Top